sentence-transformers/squad huggingface dataset:
Passage: The common features of passive solar architecture are orientation relative to the Sun, compact proportion (a low surface area to volume ratio), selective shading (overhangs) and thermal mass. When these features are tailored to the local climate and environment they can produce well-lit spaces that stay in a comfortable temperature range. Socrates' Megaron House is a classic example of passive solar design. The most recent approaches to solar design use computer modeling tying together solar lighting, heating and ventilation systems in an integrated solar design package. Active solar equipment such as pumps, fans and switchable windows can complement passive design and improve system performance.

Question: Socrate's what is a classic example of passive solar design?

Question: What is a common feature of passive solar architecture?

Question: What is produced when the features of passive solar architecture are customized to the environment?

Question: What is an example of passive solar design?

Question: What kind of equipment can improve system performance?
Passage: Urban heat islands (UHI) are metropolitan areas with higher temperatures than that of the surrounding environment. The higher temperatures are a result of increased absorption of the Solar light by urban materials such as asphalt and concrete, which have lower albedos and higher heat capacities than those in the natural environment. A straightforward method of counteracting the UHI effect is to paint buildings and roads white and plant trees. Using these methods, a hypothetical "cool communities" program in Los Angeles has projected that urban temperatures could be reduced by approximately 3 °C at an estimated cost of US$1 billion, giving estimated total annual benefits of US$530 million from reduced air-conditioning costs and healthcare savings.

Question: UHI is an abbreviation of what?

Question: A program in Los Angeles believes that with $1 billion, city temperatures could be reduced by approximately how many degrees in Celsius?

Question: What are the metropolitan areas with higher temperatures than the surrounding areas called?

Question: What materials absorb sunlight and create higher temperatures than natural materials?

Question: What is a way to reduce the high temperatures created in urban heat islands?
Passage: Agriculture and horticulture seek to optimize the capture of solar energy in order to optimize the productivity of plants. Techniques such as timed planting cycles, tailored row orientation, staggered heights between rows and the mixing of plant varieties can improve crop yields. While sunlight is generally considered a plentiful resource, the exceptions highlight the importance of solar energy to agriculture. During the short growing seasons of the Little Ice Age, French and English farmers employed fruit walls to maximize the collection of solar energy. These walls acted as thermal masses and accelerated ripening by keeping plants warm. Early fruit walls were built perpendicular to the ground and facing south, but over time, sloping walls were developed to make better use of sunlight. In 1699, Nicolas Fatio de Duillier even suggested using a tracking mechanism which could pivot to follow the Sun. Applications of solar energy in agriculture aside from growing crops include pumping water, drying crops, brooding chicks and drying chicken manure. More recently the technology has been embraced by vinters, who use the energy generated by solar panels to power grape presses.

Question: During the Little Ice Age, what did English and French farmers use to increase collection of solar energy?

Question: Vinters have adopted solar technology to do what?

Question: Why do agriculture and horticulture seek to make the most use of the solar energy captured?

Question: What are some techniques used to improve crop production?

Question: What did French and English farmers do during the Little Ice Age to gain more solar energy?

Question: What was the purpose of the fruit walls built by French and English farmers?
Passage: Greenhouses convert solar light to heat, enabling year-round production and the growth (in enclosed environments) of specialty crops and other plants not naturally suited to the local climate. Primitive greenhouses were first used during Roman times to produce cucumbers year-round for the Roman emperor Tiberius. The first modern greenhouses were built in Europe in the 16th century to keep exotic plants brought back from explorations abroad. Greenhouses remain an important part of horticulture today, and plastic transparent materials have also been used to similar effect in polytunnels and row covers.

Question: When were the first greenhouses used?

Question: In what century were the first modern greenhouses constructed?

Question: What do greenhouses do with solar energy?

Question: What is one purpose of a greenhouse?

Question: What was one of the first uses of a greenhouse?

Question: Where were the first modern greenhouses built?
Passage: Development of a solar-powered car has been an engineering goal since the 1980s. The World Solar Challenge is a biannual solar-powered car race, where teams from universities and enterprises compete over 3,021 kilometres (1,877 mi) across central Australia from Darwin to Adelaide. In 1987, when it was founded, the winner's average speed was 67 kilometres per hour (42 mph) and by 2007 the winner's average speed had improved to 90.87 kilometres per hour (56.46 mph). The North American Solar Challenge and the planned South African Solar Challenge are comparable competitions that reflect an international interest in the engineering and development of solar powered vehicles.

Question: What is the name of the solar powered car race held every two years?

Question: What was the winner of the World Solar Challenge's average speed in 2007 in km/h?

Question: What is The World Solar Challenge?

Question: When was The World Solar Challenge started?

Question: What was the average speed of a winning solar powered car in 1987?

Question: What was the average speed of a winning solar powered car by 2007?

Question: What are some other similar car races that use solar powered vehicles?
Passage: In 1975, the first practical solar boat was constructed in England. By 1995, passenger boats incorporating PV panels began appearing and are now used extensively. In 1996, Kenichi Horie made the first solar powered crossing of the Pacific Ocean, and the sun21 catamaran made the first solar powered crossing of the Atlantic Ocean in the winter of 2006–2007. There were plans to circumnavigate the globe in 2010.

Question: The first practical solar boat was constructed in what year?

Question: When was the first solar powered boat made?

Question: Who first crossed the Pacific ocean using a solar powered boat?

Question: What was the name of the first solar powered boat that crossed the Atlantic ocean?
Passage: In 1974, the unmanned AstroFlight Sunrise plane made the first solar flight. On 29 April 1979, the Solar Riser made the first flight in a solar-powered, fully controlled, man carrying flying machine, reaching an altitude of 40 feet (12 m). In 1980, the Gossamer Penguin made the first piloted flights powered solely by photovoltaics. This was quickly followed by the Solar Challenger which crossed the English Channel in July 1981. In 1990 Eric Scott Raymond in 21 hops flew from California to North Carolina using solar power. Developments then turned back to unmanned aerial vehicles (UAV) with the Pathfinder (1997) and subsequent designs, culminating in the Helios which set the altitude record for a non-rocket-propelled aircraft at 29,524 metres (96,864 ft) in 2001. The Zephyr, developed by BAE Systems, is the latest in a line of record-breaking solar aircraft, making a 54-hour flight in 2007, and month-long flights were envisioned by 2010. As of 2015, Solar Impulse, an electric aircraft, is currently circumnavigating the globe. It is a single-seat plane powered by solar cells and capable of taking off under its own power. The designed allows the aircraft to remain airborne for 36 hours.

Question: What altitude did the Solar Riser reach in feet?

Question: What is the name of the aircraft circling the globe in 2015 via solar power?

Question: When was the first unmanned flight by a solar powered plane made?

Question: When was the first solar powered manned flight made?

Question: When did the Solar Challenger cross the English Channel?

Question: Where did Eric Scott Raymond fly using a solar powered plane in 1990?

Question: How long is the solar powered plane Solar Impulse able to remain in the air?
Passage: Solar chemical processes use solar energy to drive chemical reactions. These processes offset energy that would otherwise come from a fossil fuel source and can also convert solar energy into storable and transportable fuels. Solar induced chemical reactions can be divided into thermochemical or photochemical. A variety of fuels can be produced by artificial photosynthesis. The multielectron catalytic chemistry involved in making carbon-based fuels (such as methanol) from reduction of carbon dioxide is challenging; a feasible alternative is hydrogen production from protons, though use of water as the source of electrons (as plants do) requires mastering the multielectron oxidation of two water molecules to molecular oxygen. Some have envisaged working solar fuel plants in coastal metropolitan areas by 2050 – the splitting of sea water providing hydrogen to be run through adjacent fuel-cell electric power plants and the pure water by-product going directly into the municipal water system. Another vision involves all human structures covering the earth's surface (i.e., roads, vehicles and buildings) doing photosynthesis more efficiently than plants.

Question: What is a possible alternative to making carbon-based fuels from reduction of carbon dioxide?

Question: What process converts solar energy into storable and transportable fuels?

Question: What solar process can be used to produce different fuels?
Passage: Hydrogen production technologies been a significant area of solar chemical research since the 1970s. Aside from electrolysis driven by photovoltaic or photochemical cells, several thermochemical processes have also been explored. One such route uses concentrators to split water into oxygen and hydrogen at high temperatures (2,300–2,600 °C or 4,200–4,700 °F). Another approach uses the heat from solar concentrators to drive the steam reformation of natural gas thereby increasing the overall hydrogen yield compared to conventional reforming methods. Thermochemical cycles characterized by the decomposition and regeneration of reactants present another avenue for hydrogen production. The Solzinc process under development at the Weizmann Institute uses a 1 MW solar furnace to decompose zinc oxide (ZnO) at temperatures above 1,200 °C (2,200 °F). This initial reaction produces pure zinc, which can subsequently be reacted with water to produce hydrogen.

Question: What is the name of the process under development at the Weizmann Institute?

Question: The Solznic process produces what?

Question: What has been a main area of solar chemical research since the 1970s?

Question: What is one of the thermochemical processes that has been explored besides electrolysis?

Question: What is the name of the process being developed by the Weizmann Institute?
Passage: Thermal mass systems can store solar energy in the form of heat at domestically useful temperatures for daily or interseasonal durations. Thermal storage systems generally use readily available materials with high specific heat capacities such as water, earth and stone. Well-designed systems can lower peak demand, shift time-of-use to off-peak hours and reduce overall heating and cooling requirements.

Question: In what form do thermal mass systems store solar energy?

Question: What is the system called that can store solar energy in the form of heat?

Question: What are some of the materials used in thermal storage systems?

Question: What is something that can be accomplished by a thermal mass system?
Passage: Phase change materials such as paraffin wax and Glauber's salt are another thermal storage media. These materials are inexpensive, readily available, and can deliver domestically useful temperatures (approximately 64 °C or 147 °F). The "Dover House" (in Dover, Massachusetts) was the first to use a Glauber's salt heating system, in 1948. Solar energy can also be stored at high temperatures using molten salts. Salts are an effective storage medium because they are low-cost, have a high specific heat capacity and can deliver heat at temperatures compatible with conventional power systems. The Solar Two used this method of energy storage, allowing it to store 1.44 terajoules (400,000 kWh) in its 68 cubic metres storage tank with an annual storage efficiency of about 99%.

Question: Paraffin wax is an example of what kind of storage media?

Question: The first Glauber's salt heating system was first used where?

Question: What are some examples of phase change materials?

Question: What are the approximate temperatures that can be delivered by phase change materials?

Question: What was the name of the heating system that first used Glauber's salt?

Question: Why are salts good for thermal storage?

Question: How much energy was the Solar Two able to store using salts?
Passage: Off-grid PV systems have traditionally used rechargeable batteries to store excess electricity. With grid-tied systems, excess electricity can be sent to the transmission grid, while standard grid electricity can be used to meet shortfalls. Net metering programs give household systems a credit for any electricity they deliver to the grid. This is handled by 'rolling back' the meter whenever the home produces more electricity than it consumes. If the net electricity use is below zero, the utility then rolls over the kilowatt hour credit to the next month. Other approaches involve the use of two meters, to measure electricity consumed vs. electricity produced. This is less common due to the increased installation cost of the second meter. Most standard meters accurately measure in both directions, making a second meter unnecessary.

Question: Where do off-grid PV systems store excess electricity?

Question: What do off-grid PV systems use to store excess electricity?

Question: What are the programs that gives credit to households for delivering electricity to the grid called?

Question: How is the credit to households accomplished?

Question: Why is a second meter usually unnecessary to monitor electricity use?
Passage: Pumped-storage hydroelectricity stores energy in the form of water pumped when energy is available from a lower elevation reservoir to a higher elevation one. The energy is recovered when demand is high by releasing the water, with the pump becoming a hydroelectric power generator.

Question: When water is released due to high demand, the pump become swhat?

Question: Pumped-storage hydroelectricity stores energy in what form?

Question: How is the energy stored by pumped-storage hydroelectricity recovered?
Passage: The 1973 oil embargo and 1979 energy crisis caused a reorganization of energy policies around the world and brought renewed attention to developing solar technologies. Deployment strategies focused on incentive programs such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan. Other efforts included the formation of research facilities in the US (SERI, now NREL), Japan (NEDO), and Germany (Fraunhofer Institute for Solar Energy Systems ISE).

Question: The oil embargo in what year was a contributing factor to the reorganization of energy policies?

Question: What brought attention to solar technologies in the 1970s?

Question: What are the names of some of the incentive programs used to promote solar technology?

Question: What is the name of the solar energy research facility in the US?

Question: What is the name of the solar energy research facility in Japan?

Question: What is the name of the solar energy research facility in Germany?
Passage: Commercial solar water heaters began appearing in the United States in the 1890s. These systems saw increasing use until the 1920s but were gradually replaced by cheaper and more reliable heating fuels. As with photovoltaics, solar water heating attracted renewed attention as a result of the oil crises in the 1970s but interest subsided in the 1980s due to falling petroleum prices. Development in the solar water heating sector progressed steadily throughout the 1990s and growth rates have averaged 20% per year since 1999. Although generally underestimated, solar water heating and cooling is by far the most widely deployed solar technology with an estimated capacity of 154 GW as of 2007.

Question: The solar water heaters introduced in the US in the 1890s saw growth until what time period?

Question: Since 1999, what average rate has the solar water heating sector progressed at?

Question: When did the use of solar water heaters in the US first begin?

Question: Why did interest in solar water heating decrease in the 1980s?

Question: Growth of solar water heating development has averaged how much per year since 1999

Question: What was the estimated capacity of solar water heating and cooling in 2007?
Passage: The International Energy Agency has said that solar energy can make considerable contributions to solving some of the most urgent problems the world now faces:

Question: Which organization believes that solar energy can solve some of our most pressing issues?

Question: Who said that solar energy can help solve some of the most urgent problems in the world?
Passage: The International Organization for Standardization has established a number of standards relating to solar energy equipment. For example, ISO 9050 relates to glass in building while ISO 10217 relates to the materials used in solar water heaters.

Question: ISO 9050 relates to standards for what?

Question: ISO 10217 relates to standards for what?

Question: What is the name of the standard related to glass in building?

Question: What is the name of the standard related to the materials used in solar water heaters?
Passage: It is an important source of renewable energy and its technologies are broadly characterized as either passive solar or active solar depending on the way they capture and distribute solar energy or convert it into solar power. Active solar techniques include the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.

Question: What are the technologies used to capture solar energy characterized as?

Question: What are some active solar techniques used to harness solar energy?

Question: What is an example of a passive solar technique?
Passage: The large magnitude of solar energy available makes it a highly appealing source of electricity. The United Nations Development Programme in its 2000 World Energy Assessment found that the annual potential of solar energy was 1,575–49,837 exajoules (EJ). This is several times larger than the total world energy consumption, which was 559.8 EJ in 2012.

Question: What was the total worldwide energy consumption in 2012?

Question: What is solar energy's yearly potential?

Question: What makes solar energy an appealing source of electricity>

Question: Who estimated the annual potential of solar energy in 2000?
Passage: In 2011, the International Energy Agency said that "the development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating global warming, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments; they must be wisely spent and need to be widely shared".

Question: How will solar energy increase energy security?

Question: What costs will solar energy lower?

Question: What should the cost of incentives for producing solar energy be considered?

Question: What effect will solar energy have on the price of fossil fuels?
Passage: The potential solar energy that could be used by humans differs from the amount of solar energy present near the surface of the planet because factors such as geography, time variation, cloud cover, and the land available to humans limits the amount of solar energy that we can acquire.

Question: Why does the amount of usable solar energy differ from the amount near the planets surface?
Passage: Geography effects solar energy potential because areas that are closer to the equator have a greater amount of solar radiation. However, the use of photovoltaics that can follow the position of the sun can significantly increase the solar energy potential in areas that are farther from the equator. Time variation effects the potential of solar energy because during the nighttime there is little solar radiation on the surface of the Earth for solar panels to absorb. This limits the amount of energy that solar panels can absorb in one day. Cloud cover can effect the potential of solar panels because clouds block incoming light from the sun and reduce the light available for solar cells.

Question: Why does geography have an effect of the amount of solar energy available?

Question: What is the process called that can increase solar energy in areas further away from the earth's equator?

Question: Why does time have an effect of the amount of available solar energy?

Question: What effect does cloud coverage have on the amount of solar energy available?
Passage: In addition, land availability has a large effect on the available solar energy because solar panels can only be set up on land that is unowned and suitable for solar panels. Roofs have been found to be a suitable place for solar cells, as many people have discovered that they can collect energy directly from their homes this way. Other areas that are suitable for solar cells are lands that are unowned by businesses where solar plants can be established.

Question: Why does land availability have an effect on solar energy?

Question: Why are roofs a good place for solar panels?
Passage: In 2000, the United Nations Development Programme, UN Department of Economic and Social Affairs, and World Energy Council published an estimate of the potential solar energy that could be used by humans each year that took into account factors such as insolation, cloud cover, and the land that is usable by humans. The estimate found that solar energy has a global potential of 1,575–49,837 EJ per year (see table below).

Question: What factors were taken into account in the estimate published in 2000 on solar energy?

Question: What was the total potential of solar energy found in the estimate?
Passage: Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP). CSP systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. PV converts light into electric current using the photoelectric effect.

Question: What is solar power?

Question: How is sunlight converted into electricity?

Question: What does a concentrated solar power system use?

Question: What is the purpose of a concentrated solar power system?

Question: What method does the photovoltaics system use to turn light into electricity?