Question: What were the areas at the center of an old sheet of glass called?

Answer: bull's-eyes

Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. <hl> These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as " bull's-eyes ") for decorative effect. <hl> Modern glass intended for windows is produced as float glass and is very uniform in thickness.

Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "<hl> bull's-eyes <hl>") for decorative effect. Modern glass intended for windows is produced as float glass and is very uniform in thickness.

These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as " <hl> bull's-eyes <hl> ") for decorative effect.

question: What were the areas at the center of an old sheet of glass called?, context: Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect. Modern glass intended for windows is produced as float glass and is very uniform in thickness.


Question: In early 20th century glass production, the glass was thickest at what part of the sheet?

Answer: the center

Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. <hl> The resulting glass is thicker at the location of the pour, located at the center of the large sheet. <hl> These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect. Modern glass intended for windows is produced as float glass and is very uniform in thickness.

Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at <hl> the center <hl> of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect. Modern glass intended for windows is produced as float glass and is very uniform in thickness.

question: In early 20th century glass production, the glass was thickest at what part of the sheet?, context: Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect. Modern glass intended for windows is produced as float glass and is very uniform in thickness.


Question: Currently window glass is made as what?

Answer: float glass

Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect. <hl> Modern glass intended for windows is produced as float glass and is very uniform in thickness. <hl>

Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect. Modern glass intended for windows is produced as <hl> float glass <hl> and is very uniform in thickness.

question: Currently window glass is made as what?, context: Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect. Modern glass intended for windows is produced as float glass and is very uniform in thickness.


Question: How was the bull's-eye used?

Answer: for decorative effect

Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. <hl> These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect . <hl> Modern glass intended for windows is produced as float glass and is very uniform in thickness.

Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") <hl> for decorative effect <hl>. Modern glass intended for windows is produced as float glass and is very uniform in thickness.

These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") <hl> for decorative effect <hl> .

question: How was the bull's-eye used?, context: Mass production of glass window panes in the early twentieth century caused a similar effect. In glass factories, molten glass was poured onto a large cooling table and allowed to spread. The resulting glass is thicker at the location of the pour, located at the center of the large sheet. These sheets were cut into smaller window panes with nonuniform thickness, typically with the location of the pour centered in one of the panes (known as "bull's-eyes") for decorative effect. Modern glass intended for windows is produced as float glass and is very uniform in thickness.


Question: What was the benefit of installing glass with the thick side at the bottom, in addition to avoiding water accumulation?

Answer: stability

The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. <hl> When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. <hl> Occasionally such glass has been found installed with the thicker side at the top, left or right.

The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of <hl> stability <hl> and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.

question: What was the benefit of installing glass with the thick side at the bottom, in addition to avoiding water accumulation?, context: The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.


Question: Who used to make window panes?

Answer: glassblowers

The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. <hl> The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers , the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). <hl> This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.

The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by <hl> glassblowers <hl>, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.

The reason for the observation is that in the past, when panes of glass were commonly made by <hl> glassblowers <hl> , the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above).

question: Who used to make window panes?, context: The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.


Question: What is the name for the glassmaking method that involved spinning it into sheets?

Answer: crown glass process

The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. <hl> The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process , described above). <hl> This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.

The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the <hl> crown glass process <hl>, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.

The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the <hl> crown glass process <hl> , described above).

question: What is the name for the glassmaking method that involved spinning it into sheets?, context: The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.


Question: The thickness at the bottom of glass panes was once taken as evidence that glass had features of what state of matter?

Answer: liquid

<hl> The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. <hl> This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.

The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the <hl> liquid <hl> property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.

question: The thickness at the bottom of glass panes was once taken as evidence that glass had features of what state of matter?, context: The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.


Question: When does glass stop moving like a liquid?

Answer: once solidified

The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. <hl> This assumption is incorrect, as once solidified , glass stops flowing. <hl> The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.

The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as <hl> once solidified <hl>, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.

This assumption is incorrect, as <hl> once solidified <hl> , glass stops flowing.

question: When does glass stop moving like a liquid?, context: The observation that old windows are sometimes found to be thicker at the bottom than at the top is often offered as supporting evidence for the view that glass flows over a timescale of centuries, the assumption being that the glass has exhibited the liquid property of flowing from one shape to another. This assumption is incorrect, as once solidified, glass stops flowing. The reason for the observation is that in the past, when panes of glass were commonly made by glassblowers, the technique used was to spin molten glass so as to create a round, mostly flat and even plate (the crown glass process, described above). This plate was then cut to fit a window. The pieces were not absolutely flat; the edges of the disk became a different thickness as the glass spun. When installed in a window frame, the glass would be placed with the thicker side down both for the sake of stability and to prevent water accumulating in the lead cames at the bottom of the window. Occasionally such glass has been found installed with the thicker side at the top, left or right.


Question: How is "glass" defined in physics?

Answer: a solid formed by rapid melt quenching

<hl> In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching . <hl> The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.

In physics, the standard definition of a glass (or vitreous solid) is <hl> a solid formed by rapid melt quenching <hl>. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.

In physics, the standard definition of a glass (or vitreous solid) is <hl> a solid formed by rapid melt quenching <hl> .

question: How is "glass" defined in physics?, context: In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.


Question: What is the tendency to make a glass when cooled called?

Answer: glass-forming ability

In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. <hl> The tendency for a material to form a glass while quenched is called glass-forming ability . <hl> This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.

In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called <hl> glass-forming ability <hl>. This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.

The tendency for a material to form a glass while quenched is called <hl> glass-forming ability <hl> .

question: What is the tendency to make a glass when cooled called?, context: In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.


Question: What must happen quickly for glass to form?

Answer: cooling

In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. <hl> If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. <hl> The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.

In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the <hl> cooling <hl> is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.

question: What must happen quickly for glass to form?, context: In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.


Question: What predicts glass-forming ability?

Answer: rigidity theory

In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. <hl> This ability can be predicted by the rigidity theory . <hl> Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.

In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the <hl> rigidity theory <hl>. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.

This ability can be predicted by the <hl> rigidity theory <hl> .

question: What predicts glass-forming ability?, context: In physics, the standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. The term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the supercooled liquid is frozen into the solid state at Tg. The tendency for a material to form a glass while quenched is called glass-forming ability. This ability can be predicted by the rigidity theory. Generally, the structure of a glass exists in a metastable state with respect to its crystalline form, although in certain circumstances, for example in atactic polymers, there is no crystalline analogue of the amorphous phase.


Question: What does glass not have, leading some to think it is a liquid?

Answer: first-order phase transition

<hl> Some people consider glass to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. <hl> The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. Nonetheless, the equilibrium theory of phase transformations does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.

Some people consider glass to be a liquid due to its lack of a <hl> first-order phase transition <hl> where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. Nonetheless, the equilibrium theory of phase transformations does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.

question: What does glass not have, leading some to think it is a liquid?, context: Some people consider glass to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. Nonetheless, the equilibrium theory of phase transformations does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.


Question: What theory isn't completely valid for glass?

Answer: equilibrium theory of phase transformations

Some people consider glass to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. <hl> Nonetheless, the equilibrium theory of phase transformations does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids. <hl>

Some people consider glass to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. Nonetheless, the <hl> equilibrium theory of phase transformations <hl> does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.

question: What theory isn't completely valid for glass?, context: Some people consider glass to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. Nonetheless, the equilibrium theory of phase transformations does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.


Question: Transition in glass is comparable to what?

Answer: a second-order phase transition

Some people consider glass to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. <hl> The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. <hl> Nonetheless, the equilibrium theory of phase transformations does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.

Some people consider glass to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. The glass transition may be described as analogous to <hl> a second-order phase transition <hl> where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. Nonetheless, the equilibrium theory of phase transformations does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.

question: Transition in glass is comparable to what?, context: Some people consider glass to be a liquid due to its lack of a first-order phase transition where certain thermodynamic variables such as volume, entropy and enthalpy are discontinuous through the glass transition range. The glass transition may be described as analogous to a second-order phase transition where the intensive thermodynamic variables such as the thermal expansivity and heat capacity are discontinuous. Nonetheless, the equilibrium theory of phase transformations does not entirely hold for glass, and hence the glass transition cannot be classed as one of the classical equilibrium phase transformations in solids.


Question: Atomically, glass is similar to what?

Answer: a supercooled liquid

<hl> Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid , glass tends to behave as a solid below its glass transition temperature. <hl> A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.

Although the atomic structure of glass shares characteristics of the structure in <hl> a supercooled liquid <hl>, glass tends to behave as a solid below its glass transition temperature. A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.

Although the atomic structure of glass shares characteristics of the structure in <hl> a supercooled liquid <hl> , glass tends to behave as a solid below its glass transition temperature.

question: Atomically, glass is similar to what?, context: Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as a solid below its glass transition temperature. A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.


Question: What acts like a liquid but is under the freezing temperature?

Answer: A supercooled liquid

Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as a solid below its glass transition temperature. <hl> A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. <hl> The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.

Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as a solid below its glass transition temperature. <hl> A supercooled liquid <hl> behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.

question: What acts like a liquid but is under the freezing temperature?, context: Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as a solid below its glass transition temperature. A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.


Question: Despite its atomic structure, cooled glass acts like what?

Answer: a solid

<hl> Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as a solid below its glass transition temperature. <hl> A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.

Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as <hl> a solid <hl> below its glass transition temperature. A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.

question: Despite its atomic structure, cooled glass acts like what?, context: Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as a solid below its glass transition temperature. A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.


Question: In cooled glass, what types of movement stop?

Answer: rotational and translational

Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as a solid below its glass transition temperature. A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. <hl> Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. <hl> This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.

Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as a solid below its glass transition temperature. A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas <hl> rotational and translational <hl> motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.

question: In cooled glass, what types of movement stop?, context: Although the atomic structure of glass shares characteristics of the structure in a supercooled liquid, glass tends to behave as a solid below its glass transition temperature. A supercooled liquid behaves as a liquid, but it is below the freezing point of the material, and in some cases will crystallize almost instantly if a crystal is added as a core. The change in heat capacity at a glass transition and a melting transition of comparable materials are typically of the same order of magnitude, indicating that the change in active degrees of freedom is comparable as well. Both in a glass and in a crystal it is mostly only the vibrational degrees of freedom that remain active, whereas rotational and translational motion is arrested. This helps to explain why both crystalline and non-crystalline solids exhibit rigidity on most experimental time scales.


Question: What drives the wider acceptance of renewable energy technologies?

Answer: Public policy and political leadership

<hl> Public policy and political leadership helps to "level the playing field" and drive the wider acceptance of renewable energy technologies. <hl> Countries such as Germany, Denmark, and Spain have led the way in implementing innovative policies which has driven most of the growth over the past decade. As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by 2050. There are now 144 countries with renewable energy policy targets.

<hl> Public policy and political leadership <hl> helps to "level the playing field" and drive the wider acceptance of renewable energy technologies. Countries such as Germany, Denmark, and Spain have led the way in implementing innovative policies which has driven most of the growth over the past decade. As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by 2050. There are now 144 countries with renewable energy policy targets.

question: What drives the wider acceptance of renewable energy technologies?, context: Public policy and political leadership helps to "level the playing field" and drive the wider acceptance of renewable energy technologies. Countries such as Germany, Denmark, and Spain have led the way in implementing innovative policies which has driven most of the growth over the past decade. As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by 2050. There are now 144 countries with renewable energy policy targets.


Question: Denmark has a committment to 100 percent renewable energy by what year?

Answer: 2050

Public policy and political leadership helps to "level the playing field" and drive the wider acceptance of renewable energy technologies. Countries such as Germany, Denmark, and Spain have led the way in implementing innovative policies which has driven most of the growth over the past decade. <hl> As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by 2050 . <hl> There are now 144 countries with renewable energy policy targets.

Public policy and political leadership helps to "level the playing field" and drive the wider acceptance of renewable energy technologies. Countries such as Germany, Denmark, and Spain have led the way in implementing innovative policies which has driven most of the growth over the past decade. As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by <hl> 2050 <hl>. There are now 144 countries with renewable energy policy targets.

As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by <hl> 2050 <hl> .

question: Denmark has a committment to 100 percent renewable energy by what year?, context: Public policy and political leadership helps to "level the playing field" and drive the wider acceptance of renewable energy technologies. Countries such as Germany, Denmark, and Spain have led the way in implementing innovative policies which has driven most of the growth over the past decade. As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by 2050. There are now 144 countries with renewable energy policy targets.


Question: How many countries now have renewable energy policies?

Answer: 144

Public policy and political leadership helps to "level the playing field" and drive the wider acceptance of renewable energy technologies. Countries such as Germany, Denmark, and Spain have led the way in implementing innovative policies which has driven most of the growth over the past decade. As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by 2050. <hl> There are now 144 countries with renewable energy policy targets. <hl>

Public policy and political leadership helps to "level the playing field" and drive the wider acceptance of renewable energy technologies. Countries such as Germany, Denmark, and Spain have led the way in implementing innovative policies which has driven most of the growth over the past decade. As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by 2050. There are now <hl> 144 <hl> countries with renewable energy policy targets.

question: How many countries now have renewable energy policies?, context: Public policy and political leadership helps to "level the playing field" and drive the wider acceptance of renewable energy technologies. Countries such as Germany, Denmark, and Spain have led the way in implementing innovative policies which has driven most of the growth over the past decade. As of 2014, Germany has a commitment to the "Energiewende" transition to a sustainable energy economy, and Denmark has a commitment to 100% renewable energy by 2050. There are now 144 countries with renewable energy policy targets.


Question: How much was the total investment in renewable energy in 2012?

Answer: $244 billion

<hl> Total investment in renewable energy (including small hydro-electric projects) was $244 billion in 2012, down 12% from 2011 mainly due to dramatically lower solar prices and weakened US and EU markets. <hl> As a share of total investment in power plants, wind and solar PV grew from 14% in 2000 to over 60% in 2012. The top countries for investment in recent years were China, Germany, Spain, the United States, Italy, and Brazil. Renewable energy companies include BrightSource Energy, First Solar, Gamesa, GE Energy, Goldwind, Sinovel, Trina Solar, Vestas and Yingli.

Total investment in renewable energy (including small hydro-electric projects) was <hl> $244 billion <hl> in 2012, down 12% from 2011 mainly due to dramatically lower solar prices and weakened US and EU markets. As a share of total investment in power plants, wind and solar PV grew from 14% in 2000 to over 60% in 2012. The top countries for investment in recent years were China, Germany, Spain, the United States, Italy, and Brazil. Renewable energy companies include BrightSource Energy, First Solar, Gamesa, GE Energy, Goldwind, Sinovel, Trina Solar, Vestas and Yingli.

question: How much was the total investment in renewable energy in 2012?, context: Total investment in renewable energy (including small hydro-electric projects) was $244 billion in 2012, down 12% from 2011 mainly due to dramatically lower solar prices and weakened US and EU markets. As a share of total investment in power plants, wind and solar PV grew from 14% in 2000 to over 60% in 2012. The top countries for investment in recent years were China, Germany, Spain, the United States, Italy, and Brazil. Renewable energy companies include BrightSource Energy, First Solar, Gamesa, GE Energy, Goldwind, Sinovel, Trina Solar, Vestas and Yingli.


Question: Why did the total investment in renewable energy go down in 2012?

Answer: dramatically lower solar prices

<hl> Total investment in renewable energy (including small hydro-electric projects) was $244 billion in 2012, down 12% from 2011 mainly due to dramatically lower solar prices and weakened US and EU markets. <hl> As a share of total investment in power plants, wind and solar PV grew from 14% in 2000 to over 60% in 2012. The top countries for investment in recent years were China, Germany, Spain, the United States, Italy, and Brazil. Renewable energy companies include BrightSource Energy, First Solar, Gamesa, GE Energy, Goldwind, Sinovel, Trina Solar, Vestas and Yingli.

Total investment in renewable energy (including small hydro-electric projects) was $244 billion in 2012, down 12% from 2011 mainly due to <hl> dramatically lower solar prices <hl> and weakened US and EU markets. As a share of total investment in power plants, wind and solar PV grew from 14% in 2000 to over 60% in 2012. The top countries for investment in recent years were China, Germany, Spain, the United States, Italy, and Brazil. Renewable energy companies include BrightSource Energy, First Solar, Gamesa, GE Energy, Goldwind, Sinovel, Trina Solar, Vestas and Yingli.

question: Why did the total investment in renewable energy go down in 2012?, context: Total investment in renewable energy (including small hydro-electric projects) was $244 billion in 2012, down 12% from 2011 mainly due to dramatically lower solar prices and weakened US and EU markets. As a share of total investment in power plants, wind and solar PV grew from 14% in 2000 to over 60% in 2012. The top countries for investment in recent years were China, Germany, Spain, the United States, Italy, and Brazil. Renewable energy companies include BrightSource Energy, First Solar, Gamesa, GE Energy, Goldwind, Sinovel, Trina Solar, Vestas and Yingli.


Question: What six were the top countries for investment in recent years?

Answer: China, Germany, Spain, the United States, Italy, and Brazil

Total investment in renewable energy (including small hydro-electric projects) was $244 billion in 2012, down 12% from 2011 mainly due to dramatically lower solar prices and weakened US and EU markets. As a share of total investment in power plants, wind and solar PV grew from 14% in 2000 to over 60% in 2012. <hl> The top countries for investment in recent years were China, Germany, Spain, the United States, Italy, and Brazil . <hl> Renewable energy companies include BrightSource Energy, First Solar, Gamesa, GE Energy, Goldwind, Sinovel, Trina Solar, Vestas and Yingli.

Total investment in renewable energy (including small hydro-electric projects) was $244 billion in 2012, down 12% from 2011 mainly due to dramatically lower solar prices and weakened US and EU markets. As a share of total investment in power plants, wind and solar PV grew from 14% in 2000 to over 60% in 2012. The top countries for investment in recent years were <hl> China, Germany, Spain, the United States, Italy, and Brazil <hl>. Renewable energy companies include BrightSource Energy, First Solar, Gamesa, GE Energy, Goldwind, Sinovel, Trina Solar, Vestas and Yingli.

The top countries for investment in recent years were <hl> China, Germany, Spain, the United States, Italy, and Brazil <hl> .

question: What six were the top countries for investment in recent years?, context: Total investment in renewable energy (including small hydro-electric projects) was $244 billion in 2012, down 12% from 2011 mainly due to dramatically lower solar prices and weakened US and EU markets. As a share of total investment in power plants, wind and solar PV grew from 14% in 2000 to over 60% in 2012. The top countries for investment in recent years were China, Germany, Spain, the United States, Italy, and Brazil. Renewable energy companies include BrightSource Energy, First Solar, Gamesa, GE Energy, Goldwind, Sinovel, Trina Solar, Vestas and Yingli.


Question: Who has shown support for ambitious renewable energy goals?

Answer: EU member countries

<hl> EU member countries have shown support for ambitious renewable energy goals. <hl> In 2010, Eurobarometer polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by 2020". Most people in all twenty-seven countries either approved of the target or called for it to go further. Across the EU, 57 percent thought the proposed goal was "about right" and 16 percent thought it was "too modest." In comparison, 19 percent said it was "too ambitious".

<hl> EU member countries <hl> have shown support for ambitious renewable energy goals. In 2010, Eurobarometer polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by 2020". Most people in all twenty-seven countries either approved of the target or called for it to go further. Across the EU, 57 percent thought the proposed goal was "about right" and 16 percent thought it was "too modest." In comparison, 19 percent said it was "too ambitious".

question: Who has shown support for ambitious renewable energy goals?, context: EU member countries have shown support for ambitious renewable energy goals. In 2010, Eurobarometer polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by 2020". Most people in all twenty-seven countries either approved of the target or called for it to go further. Across the EU, 57 percent thought the proposed goal was "about right" and 16 percent thought it was "too modest." In comparison, 19 percent said it was "too ambitious".


Question: What group polled the 27 EU member states in 2010?

Answer: Eurobarometer

EU member countries have shown support for ambitious renewable energy goals. <hl> In 2010, Eurobarometer polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by 2020". <hl> Most people in all twenty-seven countries either approved of the target or called for it to go further. Across the EU, 57 percent thought the proposed goal was "about right" and 16 percent thought it was "too modest." In comparison, 19 percent said it was "too ambitious".

EU member countries have shown support for ambitious renewable energy goals. In 2010, <hl> Eurobarometer <hl> polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by 2020". Most people in all twenty-seven countries either approved of the target or called for it to go further. Across the EU, 57 percent thought the proposed goal was "about right" and 16 percent thought it was "too modest." In comparison, 19 percent said it was "too ambitious".

question: What group polled the 27 EU member states in 2010?, context: EU member countries have shown support for ambitious renewable energy goals. In 2010, Eurobarometer polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by 2020". Most people in all twenty-seven countries either approved of the target or called for it to go further. Across the EU, 57 percent thought the proposed goal was "about right" and 16 percent thought it was "too modest." In comparison, 19 percent said it was "too ambitious".


Question: The goal was to increase the share of renewable energy in the EU by 20 percent in what year?

Answer: 2020

EU member countries have shown support for ambitious renewable energy goals. <hl> In 2010, Eurobarometer polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by 2020 ". <hl> Most people in all twenty-seven countries either approved of the target or called for it to go further. Across the EU, 57 percent thought the proposed goal was "about right" and 16 percent thought it was "too modest." In comparison, 19 percent said it was "too ambitious".

EU member countries have shown support for ambitious renewable energy goals. In 2010, Eurobarometer polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by <hl> 2020 <hl>". Most people in all twenty-seven countries either approved of the target or called for it to go further. Across the EU, 57 percent thought the proposed goal was "about right" and 16 percent thought it was "too modest." In comparison, 19 percent said it was "too ambitious".

In 2010, Eurobarometer polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by <hl> 2020 <hl> ".

question: The goal was to increase the share of renewable energy in the EU by 20 percent in what year?, context: EU member countries have shown support for ambitious renewable energy goals. In 2010, Eurobarometer polled the twenty-seven EU member states about the target "to increase the share of renewable energy in the EU by 20 percent by 2020". Most people in all twenty-seven countries either approved of the target or called for it to go further. Across the EU, 57 percent thought the proposed goal was "about right" and 16 percent thought it was "too modest." In comparison, 19 percent said it was "too ambitious".


Question: By the end of 2011, total renewable power capacity worldwide exceeded what number?

Answer: 1,360 GW

<hl> By the end of 2011, total renewable power capacity worldwide exceeded 1,360 GW , up 8%. <hl> Renewables producing electricity accounted for almost half of the 208 GW of capacity added globally during 2011. Wind and solar photovoltaics (PV) accounted for almost 40% and 30% . Based on REN21's 2014 report, renewables contributed 19 percent to our energy consumption and 22 percent to our electricity generation in 2012 and 2013, respectively. This energy consumption is divided as 9% coming from traditional biomass, 4.2% as heat energy (non-biomass), 3.8% hydro electricity and 2% electricity from wind, solar, geothermal, and biomass.

By the end of 2011, total renewable power capacity worldwide exceeded <hl> 1,360 GW <hl>, up 8%. Renewables producing electricity accounted for almost half of the 208 GW of capacity added globally during 2011. Wind and solar photovoltaics (PV) accounted for almost 40% and 30% . Based on REN21's 2014 report, renewables contributed 19 percent to our energy consumption and 22 percent to our electricity generation in 2012 and 2013, respectively. This energy consumption is divided as 9% coming from traditional biomass, 4.2% as heat energy (non-biomass), 3.8% hydro electricity and 2% electricity from wind, solar, geothermal, and biomass.

By the end of 2011, total renewable power capacity worldwide exceeded <hl> 1,360 GW <hl> , up 8%.

question: By the end of 2011, total renewable power capacity worldwide exceeded what number?, context: By the end of 2011, total renewable power capacity worldwide exceeded 1,360 GW, up 8%. Renewables producing electricity accounted for almost half of the 208 GW of capacity added globally during 2011. Wind and solar photovoltaics (PV) accounted for almost 40% and 30% . Based on REN21's 2014 report, renewables contributed 19 percent to our energy consumption and 22 percent to our electricity generation in 2012 and 2013, respectively. This energy consumption is divided as 9% coming from traditional biomass, 4.2% as heat energy (non-biomass), 3.8% hydro electricity and 2% electricity from wind, solar, geothermal, and biomass.


Question: Renewables contributed what percentage to our energy consumption?

Answer: 19 percent

By the end of 2011, total renewable power capacity worldwide exceeded 1,360 GW, up 8%. Renewables producing electricity accounted for almost half of the 208 GW of capacity added globally during 2011. Wind and solar photovoltaics (PV) accounted for almost 40% and 30% . <hl> Based on REN21's 2014 report, renewables contributed 19 percent to our energy consumption and 22 percent to our electricity generation in 2012 and 2013, respectively. <hl> This energy consumption is divided as 9% coming from traditional biomass, 4.2% as heat energy (non-biomass), 3.8% hydro electricity and 2% electricity from wind, solar, geothermal, and biomass.

By the end of 2011, total renewable power capacity worldwide exceeded 1,360 GW, up 8%. Renewables producing electricity accounted for almost half of the 208 GW of capacity added globally during 2011. Wind and solar photovoltaics (PV) accounted for almost 40% and 30% . Based on REN21's 2014 report, renewables contributed <hl> 19 percent <hl> to our energy consumption and 22 percent to our electricity generation in 2012 and 2013, respectively. This energy consumption is divided as 9% coming from traditional biomass, 4.2% as heat energy (non-biomass), 3.8% hydro electricity and 2% electricity from wind, solar, geothermal, and biomass.

question: Renewables contributed what percentage to our energy consumption?, context: By the end of 2011, total renewable power capacity worldwide exceeded 1,360 GW, up 8%. Renewables producing electricity accounted for almost half of the 208 GW of capacity added globally during 2011. Wind and solar photovoltaics (PV) accounted for almost 40% and 30% . Based on REN21's 2014 report, renewables contributed 19 percent to our energy consumption and 22 percent to our electricity generation in 2012 and 2013, respectively. This energy consumption is divided as 9% coming from traditional biomass, 4.2% as heat energy (non-biomass), 3.8% hydro electricity and 2% electricity from wind, solar, geothermal, and biomass.


Question: Renewables contributed what percentage to our electricity generation?

Answer: 22 percent

By the end of 2011, total renewable power capacity worldwide exceeded 1,360 GW, up 8%. Renewables producing electricity accounted for almost half of the 208 GW of capacity added globally during 2011. Wind and solar photovoltaics (PV) accounted for almost 40% and 30% . <hl> Based on REN21's 2014 report, renewables contributed 19 percent to our energy consumption and 22 percent to our electricity generation in 2012 and 2013, respectively. <hl> This energy consumption is divided as 9% coming from traditional biomass, 4.2% as heat energy (non-biomass), 3.8% hydro electricity and 2% electricity from wind, solar, geothermal, and biomass.

By the end of 2011, total renewable power capacity worldwide exceeded 1,360 GW, up 8%. Renewables producing electricity accounted for almost half of the 208 GW of capacity added globally during 2011. Wind and solar photovoltaics (PV) accounted for almost 40% and 30% . Based on REN21's 2014 report, renewables contributed 19 percent to our energy consumption and <hl> 22 percent <hl> to our electricity generation in 2012 and 2013, respectively. This energy consumption is divided as 9% coming from traditional biomass, 4.2% as heat energy (non-biomass), 3.8% hydro electricity and 2% electricity from wind, solar, geothermal, and biomass.

question: Renewables contributed what percentage to our electricity generation?, context: By the end of 2011, total renewable power capacity worldwide exceeded 1,360 GW, up 8%. Renewables producing electricity accounted for almost half of the 208 GW of capacity added globally during 2011. Wind and solar photovoltaics (PV) accounted for almost 40% and 30% . Based on REN21's 2014 report, renewables contributed 19 percent to our energy consumption and 22 percent to our electricity generation in 2012 and 2013, respectively. This energy consumption is divided as 9% coming from traditional biomass, 4.2% as heat energy (non-biomass), 3.8% hydro electricity and 2% electricity from wind, solar, geothermal, and biomass.


Question: Who was the UN under-secretary in 2011?

Answer: Achim Steiner

During the five-years from the end of 2004 through 2009, worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies. <hl> In 2011, UN under-secretary general Achim Steiner said: "The continuing growth in this core segment of the green economy is not happening by chance. <hl> The combination of government target-setting, policy support and stimulus funds is underpinning the renewable industry's rise and bringing the much needed transformation of our global energy system within reach." He added: "Renewable energies are expanding both in terms of investment, projects and geographical spread. In doing so, they are making an increasing contribution to combating climate change, countering energy poverty and energy insecurity".

During the five-years from the end of 2004 through 2009, worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies. In 2011, UN under-secretary general <hl> Achim Steiner <hl> said: "The continuing growth in this core segment of the green economy is not happening by chance. The combination of government target-setting, policy support and stimulus funds is underpinning the renewable industry's rise and bringing the much needed transformation of our global energy system within reach." He added: "Renewable energies are expanding both in terms of investment, projects and geographical spread. In doing so, they are making an increasing contribution to combating climate change, countering energy poverty and energy insecurity".

question: Who was the UN under-secretary in 2011?, context: During the five-years from the end of 2004 through 2009, worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies. In 2011, UN under-secretary general Achim Steiner said: "The continuing growth in this core segment of the green economy is not happening by chance. The combination of government target-setting, policy support and stimulus funds is underpinning the renewable industry's rise and bringing the much needed transformation of our global energy system within reach." He added: "Renewable energies are expanding both in terms of investment, projects and geographical spread. In doing so, they are making an increasing contribution to combating climate change, countering energy poverty and energy insecurity".


Question: Between what years did worldwide renewable energy capacity grow at rates of 10 to 60 percent annually?

Answer: 2004 through 2009

<hl> During the five-years from the end of 2004 through 2009 , worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies. <hl> In 2011, UN under-secretary general Achim Steiner said: "The continuing growth in this core segment of the green economy is not happening by chance. The combination of government target-setting, policy support and stimulus funds is underpinning the renewable industry's rise and bringing the much needed transformation of our global energy system within reach." He added: "Renewable energies are expanding both in terms of investment, projects and geographical spread. In doing so, they are making an increasing contribution to combating climate change, countering energy poverty and energy insecurity".

During the five-years from the end of <hl> 2004 through 2009 <hl>, worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies. In 2011, UN under-secretary general Achim Steiner said: "The continuing growth in this core segment of the green economy is not happening by chance. The combination of government target-setting, policy support and stimulus funds is underpinning the renewable industry's rise and bringing the much needed transformation of our global energy system within reach." He added: "Renewable energies are expanding both in terms of investment, projects and geographical spread. In doing so, they are making an increasing contribution to combating climate change, countering energy poverty and energy insecurity".

During the five-years from the end of <hl> 2004 through 2009 <hl> , worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies.

question: Between what years did worldwide renewable energy capacity grow at rates of 10 to 60 percent annually?, context: During the five-years from the end of 2004 through 2009, worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies. In 2011, UN under-secretary general Achim Steiner said: "The continuing growth in this core segment of the green economy is not happening by chance. The combination of government target-setting, policy support and stimulus funds is underpinning the renewable industry's rise and bringing the much needed transformation of our global energy system within reach." He added: "Renewable energies are expanding both in terms of investment, projects and geographical spread. In doing so, they are making an increasing contribution to combating climate change, countering energy poverty and energy insecurity".


Question: Who is Achim Steiner?

Answer: UN under-secretary general

During the five-years from the end of 2004 through 2009, worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies. <hl> In 2011, UN under-secretary general Achim Steiner said: "The continuing growth in this core segment of the green economy is not happening by chance. <hl> The combination of government target-setting, policy support and stimulus funds is underpinning the renewable industry's rise and bringing the much needed transformation of our global energy system within reach." He added: "Renewable energies are expanding both in terms of investment, projects and geographical spread. In doing so, they are making an increasing contribution to combating climate change, countering energy poverty and energy insecurity".

During the five-years from the end of 2004 through 2009, worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies. In 2011, <hl> UN under-secretary general <hl> Achim Steiner said: "The continuing growth in this core segment of the green economy is not happening by chance. The combination of government target-setting, policy support and stimulus funds is underpinning the renewable industry's rise and bringing the much needed transformation of our global energy system within reach." He added: "Renewable energies are expanding both in terms of investment, projects and geographical spread. In doing so, they are making an increasing contribution to combating climate change, countering energy poverty and energy insecurity".

question: Who is Achim Steiner?, context: During the five-years from the end of 2004 through 2009, worldwide renewable energy capacity grew at rates of 10–60 percent annually for many technologies. In 2011, UN under-secretary general Achim Steiner said: "The continuing growth in this core segment of the green economy is not happening by chance. The combination of government target-setting, policy support and stimulus funds is underpinning the renewable industry's rise and bringing the much needed transformation of our global energy system within reach." He added: "Renewable energies are expanding both in terms of investment, projects and geographical spread. In doing so, they are making an increasing contribution to combating climate change, countering energy poverty and energy insecurity".


Question: Which group projected that solar plant may produce most of the world's electricity within 50 years?

Answer: International Energy Agency

<hl> According to a 2011 projection by the International Energy Agency , solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. <hl> The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 – and half of all energy needs – with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity".

According to a 2011 projection by the <hl> International Energy Agency <hl>, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 – and half of all energy needs – with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity".

According to a 2011 projection by the <hl> International Energy Agency <hl> , solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment.

question: Which group projected that solar plant may produce most of the world's electricity within 50 years?, context: According to a 2011 projection by the International Energy Agency, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 – and half of all energy needs – with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity".


Question: Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by what year?

Answer: 2060

According to a 2011 projection by the International Energy Agency, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. <hl> The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 – and half of all energy needs – with wind, hydropower and biomass plants supplying much of the remaining generation". <hl> "Photovoltaic and concentrated solar power together can become the major source of electricity".

According to a 2011 projection by the International Energy Agency, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by <hl> 2060 <hl> – and half of all energy needs – with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity".

question: Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by what year?, context: According to a 2011 projection by the International Energy Agency, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 – and half of all energy needs – with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity".


Question: Photovoltaic and solar-thermal plants may meet how much of the world's energy needs by 2060?

Answer: half

According to a 2011 projection by the International Energy Agency, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. <hl> The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 – and half of all energy needs – with wind, hydropower and biomass plants supplying much of the remaining generation". <hl> "Photovoltaic and concentrated solar power together can become the major source of electricity".

According to a 2011 projection by the International Energy Agency, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 – and <hl> half <hl> of all energy needs – with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity".

question: Photovoltaic and solar-thermal plants may meet how much of the world's energy needs by 2060?, context: According to a 2011 projection by the International Energy Agency, solar power plants may produce most of the world's electricity within 50 years, significantly reducing the emissions of greenhouse gases that harm the environment. The IEA has said: "Photovoltaic and solar-thermal plants may meet most of the world's demand for electricity by 2060 – and half of all energy needs – with wind, hydropower and biomass plants supplying much of the remaining generation". "Photovoltaic and concentrated solar power together can become the major source of electricity".


Question: Who led the world in renewable energy production in 2013?

Answer: China

<hl> In 2013, China led the world in renewable energy production, with a total capacity of 378 GW, mainly from hydroelectric and wind power. <hl> As of 2014, China leads the world in the production and use of wind power, solar photovoltaic power and smart grid technologies, generating almost as much water, wind and solar energy as all of France and Germany's power plants combined. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity. Since 2005, production of solar cells in China has expanded 100-fold. As Chinese renewable manufacturing has grown, the costs of renewable energy technologies have dropped. Innovation has helped, but the main driver of reduced costs has been market expansion.

In 2013, <hl> China <hl> led the world in renewable energy production, with a total capacity of 378 GW, mainly from hydroelectric and wind power. As of 2014, China leads the world in the production and use of wind power, solar photovoltaic power and smart grid technologies, generating almost as much water, wind and solar energy as all of France and Germany's power plants combined. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity. Since 2005, production of solar cells in China has expanded 100-fold. As Chinese renewable manufacturing has grown, the costs of renewable energy technologies have dropped. Innovation has helped, but the main driver of reduced costs has been market expansion.

question: Who led the world in renewable energy production in 2013?, context: In 2013, China led the world in renewable energy production, with a total capacity of 378 GW, mainly from hydroelectric and wind power. As of 2014, China leads the world in the production and use of wind power, solar photovoltaic power and smart grid technologies, generating almost as much water, wind and solar energy as all of France and Germany's power plants combined. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity. Since 2005, production of solar cells in China has expanded 100-fold. As Chinese renewable manufacturing has grown, the costs of renewable energy technologies have dropped. Innovation has helped, but the main driver of reduced costs has been market expansion.


Question: Since what year has production of solar cells in China expanded 100-fold?

Answer: 2005

In 2013, China led the world in renewable energy production, with a total capacity of 378 GW, mainly from hydroelectric and wind power. As of 2014, China leads the world in the production and use of wind power, solar photovoltaic power and smart grid technologies, generating almost as much water, wind and solar energy as all of France and Germany's power plants combined. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity. <hl> Since 2005 , production of solar cells in China has expanded 100-fold. <hl> As Chinese renewable manufacturing has grown, the costs of renewable energy technologies have dropped. Innovation has helped, but the main driver of reduced costs has been market expansion.

In 2013, China led the world in renewable energy production, with a total capacity of 378 GW, mainly from hydroelectric and wind power. As of 2014, China leads the world in the production and use of wind power, solar photovoltaic power and smart grid technologies, generating almost as much water, wind and solar energy as all of France and Germany's power plants combined. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity. Since <hl> 2005 <hl>, production of solar cells in China has expanded 100-fold. As Chinese renewable manufacturing has grown, the costs of renewable energy technologies have dropped. Innovation has helped, but the main driver of reduced costs has been market expansion.

Since <hl> 2005 <hl> , production of solar cells in China has expanded 100-fold.

question: Since what year has production of solar cells in China expanded 100-fold?, context: In 2013, China led the world in renewable energy production, with a total capacity of 378 GW, mainly from hydroelectric and wind power. As of 2014, China leads the world in the production and use of wind power, solar photovoltaic power and smart grid technologies, generating almost as much water, wind and solar energy as all of France and Germany's power plants combined. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity. Since 2005, production of solar cells in China has expanded 100-fold. As Chinese renewable manufacturing has grown, the costs of renewable energy technologies have dropped. Innovation has helped, but the main driver of reduced costs has been market expansion.


Question: What is the main driver of reduced costs?

Answer: market expansion

In 2013, China led the world in renewable energy production, with a total capacity of 378 GW, mainly from hydroelectric and wind power. As of 2014, China leads the world in the production and use of wind power, solar photovoltaic power and smart grid technologies, generating almost as much water, wind and solar energy as all of France and Germany's power plants combined. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity. Since 2005, production of solar cells in China has expanded 100-fold. As Chinese renewable manufacturing has grown, the costs of renewable energy technologies have dropped. <hl> Innovation has helped, but the main driver of reduced costs has been market expansion . <hl>

In 2013, China led the world in renewable energy production, with a total capacity of 378 GW, mainly from hydroelectric and wind power. As of 2014, China leads the world in the production and use of wind power, solar photovoltaic power and smart grid technologies, generating almost as much water, wind and solar energy as all of France and Germany's power plants combined. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity. Since 2005, production of solar cells in China has expanded 100-fold. As Chinese renewable manufacturing has grown, the costs of renewable energy technologies have dropped. Innovation has helped, but the main driver of reduced costs has been <hl> market expansion <hl>.

Innovation has helped, but the main driver of reduced costs has been <hl> market expansion <hl> .

question: What is the main driver of reduced costs?, context: In 2013, China led the world in renewable energy production, with a total capacity of 378 GW, mainly from hydroelectric and wind power. As of 2014, China leads the world in the production and use of wind power, solar photovoltaic power and smart grid technologies, generating almost as much water, wind and solar energy as all of France and Germany's power plants combined. China's renewable energy sector is growing faster than its fossil fuels and nuclear power capacity. Since 2005, production of solar cells in China has expanded 100-fold. As Chinese renewable manufacturing has grown, the costs of renewable energy technologies have dropped. Innovation has helped, but the main driver of reduced costs has been market expansion.