Innovation for Our Energy Future

National Renewable Energy Laboratory

Innovation for Our Energy Future

National Renewable Energy Laboratory

Innovation for Our Energy Future

National Renewable Energy Laboratory

Innovation for Our Energy Future

National Renewable Energy Laboratory

Innovation for Our Energy Future

National Renewable Energy Laboratory

Innovation for Our Energy Future

A national laboratory of the U.S. Department of Energy Office of 

Energy Efficiency & Renewable Energy

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2006 Research Review
	 2006 NRELResearchReview

	 1	 Director’s Perspective

	 2	 NREL In Focus

	 2	 	 AStructure for Translational Science

	 2	 	 NREL Goes “Carbon Neutral”

	 3	 	 NREL and Universities Form New Partnership

	 3	 	 President Bush Visits NREL

4	 Awards and Honors

	 4	 	 National Bioenergy Center Wins Technology TransferAwards

	 4	 	 Three NRELRetirees Receive Emeritus Designation

	 4	 	 Kazmerski Receives Solar and MaterialsAwards

	 5	 	 Chum Earns Green Engineering Honor

	 5	 	 Kutscher Tapped for Solar EnergyAward

	 6	 Clean Energy’s Next Revolution

	 7	 	 Advanced Batteries

	 8	 	 Solar Power

	 12	 	 Cellulosic Ethanol

	 13	 	 Hydrogen

	 15	 	 Wind Power

	 16	 WinDS of Change

	 20	 Next-Generation Fuels—What’s Old Is New Again

	 25	 Capitalizing on the Nation’s Investment

The National Renewable Energy Laboratory is operated by Midwest Research Institute and Battelle for the Office of Energy 

Efficiency and Renewable Energy (EERE) at the U.S. Department of Energy (DOE). NREL is funded by EERE, the DOE Office 

of Basic Energy Sciences, and other funding sources. NREL is the nation’s primary national laboratory for renewable energy 

and energy efficiency research and development. 

The Research Review is published yearly and describes the laboratory’s accomplishments in science and technology to a 

wide audience. The purpose is not simply to describe the progress being made, but also to show the promise and value of 

NREL’s R&D to people, industry, the nation, and the world.

This year’s Research Review staff includes Kevin Eber, Howard Brown, Ray David, Grace Griego, Linda Hill, 

Michelle Kubik, Paula Pitchford, and Gary Schmitz.

Cover photo: Researcher Michael Heben

Table of Contents
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 

PIX14353

These are exciting times for those of us fortunate enough to work in the field of renewable energy and energy efficiency.

Never before have we witnessed such intense interest in—and rapid growth 

of—renewable energy and efficiency technologies. In particular, the industries for solar, 

wind, and biomass energy systems are expanding at rates exceeding 30% annually.

And yet, as the drive to commercialize existing technologies reaches new heights, 

there has never been a greater need for the innovative research that will be required 

to deliver subsequent generations of renewable energy and energy efficiency 

technologies, to make tomorrow’s energy solutions more economically and 

environmentally beneficial and less costly than those available today.

President George W. Bush’s visit to the National Renewable Energy Laboratory (NREL) 

in 2006 underscored the important role the laboratory is playing in moving our nation 

toward a more secure and more sustainable energy future. That the president chose 

the NREL campus as the locale for a “national dialogue” on energy issues made it clear 

that our work can indeed make a difference for the United States.

This past year also saw NREL being recognized for its leadership in reducing the 

environmental impacts of its facilities and operations. Our Sustainable NREL program 

has not only employed renewable energy to offset the total energy use of our buildings, 

but also the energy used by NREL vehicles, employee commuting, air travel, and other“ 

life cycle” energy consumption as well. I am proud of our commitment to “walk the 

talk,” by putting to productive use many of the same renewable energy and energy 

efficiency concepts and systems we have had a hand in developing over the years.

I’m pleased to say that our evolving plans for the “build out” of the NREL’s research 

campus—ensuring that we have the new laboratories and other facilities our work will 

require over the next several decades—reflects that same commitment to minimizing 

our organization’s energy and environmental footprint.

A key example of this commitment is NREL’s new Science and Technology Facility. As 

this publication was about to go to press, the facility was certified as the first federal 

building to earn LEED Platinum from U.S. Green Building Council. LEED stands for 

Leadership in Energy and Environmental Design, and Platinum is the highest rating 

under the LEED Green Building Rating System.

As we look to the future, it is becoming clear that our nation must increasingly rely on 

the useful innovations that can only come from research if we are to continue to thrive. 

Fittingly, a report recently released by the Council on Competitiveness advises: “For the 

next quarter century, we must optimize our entire society for innovation.”

Putting innovation front and center: that’s the philosophy on which this laboratory 

was built, and it is the spirit that underlies what we strive to achieve here every 

day. Our mission at NREL has never been more relevant, and our work never more 

consequential, than it is today. n

Dr. Dan Arvizu

Director’s Perspective
	 2006 NRELResearchReview

PIX15027 PIX11949

A Structure for Translational

Science

In 2006, NREL created an organizational structure that facilitates work in 

translational science and reflects the 

laboratory’s commitment to developing 

sustainable, accessible, affordable energy 

technologies to power the homes, businesses, and automobiles of the future.

Translational science at NREL focuses on 

renewable energy and energy efficiency 

innovations that will most benefit the 

nation in practical applications. The new 

organization reflects four main areas of 

expertise: renewable electricity science 

and technology, renewable fuels 

science and technology, basic energy 

sciences, and strategic analysis. Each 

area is represented in NREL’s R&D and 

analytical centers.

The Renewable Electricity Science and 

Technology directorate is home to 

R&D centers for solar and wind power, distributed power generation, and 

energy-efficient buildings; it is headed 

by Associate Director Stanley Bull, who 

has had extensive management experience in more than 35 years of work in 

energy-related R&D.

Renewable Fuels Science and Technology is led by Associate Director Dale 

Gardner, who is experienced in hydrogen systems integration and was formerly a manager at Northrop Grumman 

Mission Systems. His directorate focuses 

on R&D in bioenergy, hydrogen, and 

transportation technologies.

Energy Sciences, headed by Associate 

Director Ray Stults, includes research 

centers in basic chemical, material, and 

biosciences as well as a scientific computing center. His background includes 

management positions in basic sciences R&D at three other U.S. Department 

of Energy (DOE) national laboratories: 

Idaho National Laboratory, Los Alamos 

National Laboratory, and Pacific Northwest National Laboratory (PNNL).

Strategic Development and Analysis 

focuses on important issues of technology transfer, energy economics, applications, and markets and is led by Associate Director Bobi Garrett, who held 

several management and program leadership positions at PNNL before joining 

NREL. n

NREL Goes “Carbon

Neutral”

It’s official: NREL is carbon neutral. 

Because the laboratory purchases 30 

million kilowatt-hours of renewable energy certificates annually through DOE’s 

Western Area Power Administration, 

NREL’s activities produce no net greenhouse gas emissions over the course of 

a year. Certificate purchases offset all 

the energy NREL uses annually in buildings, vehicles, and day-to-day activities, 

including the energy used by staff members in commuting and air travel.

This helped to earn NREL a Climate 

Protection Award from the U.S. Environmental Protection Agency (EPA) in 

2006. The award included recognition 

for NREL’s significant analytical contributions to EPA’s Mobile Air Conditioning 

Climate Protection Partnership, which 

could help reduce automotive carbon 

dioxide emissions by more than 35 billion kilograms per year.

In addition, NREL produces solar- and 

wind-generated power on site, uses alternative fuels in fleet vehicles, and helps 

to design its own energy-efficient buildings. Several facilities feature passive 

solar heating, natural lighting, energyefficient equipment, and solar-heated 

water and ventilation air. Features like 

these earned NREL’s new Science and 

Technology Facility a federal showcase 

designation in 2006 from the DOE Federal Energy Management Program.

These are just some of the many staff members who drive hybrid and other fuel-efficient vehicles 

to and from work at NREL.

NREL Associate Directors (left to right) Ray Stults, Bobi Garrett, Stan Bull, and Dale Gardner.

NREL In Focus
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 

Also in 2006, the Office of the Federal 

Environmental Executive recognized the 

Sustainable NREL initiative with a White 

House Closing the Circle Award Honorable Mention. Laboratory Director Dan 

Arvizu said the award is important in 

that it reflects NREL’s goals for leadership in environmental management and 

sustainability. n

NREL and Universities Form

New Partnership

To help move clean, affordable energy 

technologies quickly to markets in 

its home state and beyond, NREL has 

joined with three Colorado institutions 

of higher learning in a new partnership, the Colorado Renewable Energy 

Collaboratory.

The Collaboratory is made up of renewable energy researchers from NREL, the 

Colorado School of Mines, Colorado 

State University, and the University of 

Colorado, Boulder. The State of Colorado 

is providing up to $2 million per year in 

matching funds for the Collaboratory to 

pursue federally and privately funded 

R&D projects over the next three years. 

Income from spin-off commercial technologies will be used to reimburse the 

state for the matching funds.

The Collaboratory has already submitted a proposal to DOE for an R&D center for producing solar hydrogen and 

electricity via photoelectrochemistry, 

photochemistry, and photobiology. 

NREL Research Fellow Art Nozik would 

be the Lead Principal Investigator of a 

team consisting of approximately 30 

NREL scientists, 35 faculty members, 30 

graduate students, and 35 postdoctoral 

researchers. The idea for the partnership 

emerged from the Renewable Energy 

Summit hosted in early 2006 by U.S. 

Senator Ken Salazar of Colorado. n

	 PresidentBushVisitsNREL

President George W. Bush visited 

NREL in 2006 to tour a key laboratory facility and to lead a panel 

that discussed approaches to 

achieving the goals of his 

Advanced Energy Initiative, which aims to develop the foundations for a 

reliable, affordable, and 

clean energy future.

The visit began with 

a tour of NREL’s 

Biochemical Process 

Development Unit led 

by Michael Pacheco, 

director of the National 

Bioenergy Center. During the tour, the president was given a basic 

overview of the process 

of converting cellulosic 

biomass to ethanol.

Later the president led a panel discussion on the best and most promising 

alternatives to the use of oil. The panel included NREL Director Dan Arvizu; Larry Burns, vice president, Research and Development, General Motors (GM); Bill 

Frey, Global Business director, Biobased Materials, DuPont; Dale Gardner, NREL 

associate director, Renewable Fuels Science and Technology; Patty Stulp, president, Ethanol Management Company; Lori Vaclavik, executive director, Habitat 

for Humanity of Metro Denver; and Pat Vincent, president and CEO, Public Service Company of Colorado.

President Bush said that dependence on foreign oil is a threat to both economic stability and national security, and he recognized NREL’s work as important in 

developing viable alternatives. He proposed doubling funding for basic sciences research and developing alternative fuels, plug-in hybrids, and hydrogenpowered vehicles as well as advanced electricity generation technologies.

“We’re close to changing the way we live in an incredibly positive way,” the 

president said.

During the discussion, Arvizu described some of the exciting progress being 

made in photovoltaic technologies, and Burns talked about new ways that GM 

is marketing its considerable fleet of flexible-fuel vehicles. Stulp pointed out 

how growing corn for ethanol boosts the supply of domestic fuels and creates 

new markets for America’s farmers. Frey cited GM’s long partnership with NREL 

on hybrids and talked about new work to develop biorefineries for producing 

valuable fuels, chemicals, and materials from biomass.

Vaclavik said Habitat for Humanity has worked with NREL to provide comfortable, affordable homes that use little or no net energy because of their energy 

efficiency and integrated solar systems. Gardner described the promise of hydrogen technology and current work on producing and storing it cost effectively. 

Finally, Vincent talked about Public Service’s “Windsource” program, advanced 

wind turbine technologies, and plans for new solar power stations.

The president said that future generations would appreciate the work of these 

pioneers and entrepreneurs. His visit to NREL was the second by a U.S. president; 

the first was by former President Jimmy Carter in 1978. n Credit: Daniel Hansen, White House

President Bush tours the NREL’s National Bioenergy Center 

and hosts a panel discussion with NREL Director Dan Arvizu.
	 	 2006 NRELResearchReview

first three NREL researchers to receive 

the honorary title of emeritus. NREL 

presents the honorary title to distinguished retirees in recognition of their 

extensive contributions. Though the 

three are retired, they continue to share 

their knowledge and expertise with the 

laboratory.

Before being appointed emeritus 

researcher, Tom Milne was a visiting 

scientist at NREL’s National Bioenergy 

Center. Milne, who came to NREL in 

1977 and retired in 1996, is known for 

his work on the thermochemical conversion of biomass using molecular 

beam mass spectrometry. He is credited with developing the fundamental 

knowledge underpinning advanced 

thermochemical technologies.

Emeritus Researcher Dick Crandall, who 

worked at NREL from 1987 to 2006, 

has been a leader in developing highperformance, thin-film photovoltaic 

(PV) devices. He led the PV community in developing the tools needed to 

understand the electronic activity of 

PIX15029

disordered material. A proactive mentor, he created NREL’s working group 

on defects in PV materials and brought 

together scientists from throughout the 

laboratory.

Emeritus Researcher Dick Ahrenkiel 

came to NREL in 1981 and retired in 

2005. He specializes in measuring and 

characterizing PV cells and materials, and he is one of the world’s most 

well-known experts in measuring the 

lifetimes of charge carriers within solar 

cells. n

Kazmerski Receives Solar

and Materials Awards

Larry Kazmerski, director of NREL’s National Center for Photovoltaics, received 

the World PV Award in May 2006 for his 

outstanding contributions to the worldwide advancements of PV science and 

technology. Sponsored by professional 

organizations from the European, AsianPacific Rim, and American PV communities, the award recognizes superior 

and sustained leadership in solar PV 

technologies.

National Bioenergy Center

Wins Technology Transfer

Awards

The Federal Laboratory Consortium 

(FLC) honored NREL’s National Bioenergy Center with two Notable Technology 

Development awards for the center’s 

work on an integrated biorefinery 

and on a related process for deriving 

chemicals from biomass. FLC recognizes 

federal laboratories and agencies for 

excellence in transferring governmentsponsored technologies to the public 

and private sectors.

One award credits NREL for signing a 

$7.7 million Cooperative Research and 

Development Agreement with DuPont 

to jointly develop, build, and test a 

biorefinery pilot process that will convert 

the entire corn plant—kernels, leaves, 

and stalks—into ethanol, chemicals, and 

electric power. DuPont leads a team that 

includes NREL, Diversa Corporation, Michigan State University, and Deere & Co.

NREL was also honored for a highly 

efficient, single-phase process that converts cellulosic biomass—such as grain 

hulls and other agricultural residues—

into pure streams of lignin, cellulose, 

and dissolved sugars. These are valuable and useful materials for the fuels, 

chemicals, food, packaging, and pulp 

and paper industries. NREL secured a 

worldwide exclusive technology license, 

shared between UTEK and Xethanol 

Corporation, and is working with Xethanol as the company develops and commercializes the new technology. n

Three NREL Retirees

Honored with Emeritus

Designation

In 2006, Thomas R. Milne, Richard Crandall, and Richard Ahrenkiel became the 

NREL retirees Tom Milne, Dick Crandall, and Dick Ahrenkiel (left to right) have received the 

honorary title of emeritus. 

Awards and Honors The knowledge, innovation, and creativity of 

our researchers make NREL the nation’s premier laboratory for research and development in 

renewable energy and energy efficiency. These awards and honors underscore their contributions 

and their dedication to science and technology and to NREL’s mission.
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	  PIX00957 PIX14920

PIX15028

Kazmerski also received the Nelson W. 

Taylor Award in 2006. The Department 

of Materials Science and Engineering at 

Pennsylvania State University has been 

recognizing outstanding achievements 

and contributions in the field of materials science since 1970. Past awardees 

include Nobel Prize winners Alan G. 

MacDiarmid, Richard E. Smalley, and 

Linus Pauling.

The first scientist hired by NREL for 

PV research, Kazmerski has published 

more than 310 journal papers on solar 

cells, thin films, semiconductor materials and devices, surface and interface 

analysis, scanning probe microscopy, 

nanoscale technology, high-temperature superconductivity, and semiconductor defects. An author and editor of 

four books, he is editor-in-chief of the 

Elsevier journal Renewable and Sustainable Energy Reviews.

Kazmerski is a fellow of the Institute of 

Electrical and Electronics Engineers, 

the American Physical Society, and the 

American Vacuum Society. He has won 

three R&D 100 awards for novel measurement and characterization devices. Kazmerski was inducted into the 

National Academy of Engineering in 

2005. n

Chum Earns Green

Engineering Honor

Helena Chum, group manager of 

Biorefinery Analysis and Exploratory Research, became the first person 

to receive the “Individual Trail Blazer” 

award from HENAAC and Green Technology Magazine in October 2006. The 

award cites her research and development work in bioenergy and renewable hydrogen production. Her work 

aims to solve the challenges involved 

in converting the world’s vast biomass 

resources to energy and related products.

HENAAC, formerly the Hispanic Engineer National Achievement Awards 

Conference, is a nonprofit organization dedicated to promoting careers in 

science, technology, engineering, and 

math. Chum was honored as part of the 

first annual Green Engineering Honors at the October 

2006 HENAAC conference.

“Ever since my early research 

years in my native Brazil, I 

envisioned bridging the gap 

between research in the 

laboratory and technology 

development—the creation 

of technology companies 

and commercialization of the 

technologies—which leads 

in turn to economic development,” says Chum.

Working with NREL staff, 

industry, and academia, 

she has been building that 

bridge in the United States 

and in Brazil, thanks to bilateral programs. Since joining the laboratory in 

1979, she has also monitored many 

young women and minorities and hosted a number of Hispanic professionals 

and Latin American students at NREL. n

Kutscher Tapped for Solar

Energy Award

For his outstanding contributions in the 

research and development of active 

solar energy systems and solar thermal 

technologies, NREL’s Chuck Kutscher 

was honored with the Charles Greeley 

Abbot Award at the 2006 annual conference of the American Solar Energy 

Society.

“During my 28 years at NREL, I’ve been 

fortunate to work on talented teams 

of solar researchers,” says Kutscher. “My 

past and present colleagues very deservedly share in this award.”

Kutscher is a group manager in NREL’s 

Center for Buildings and Thermal Systems. His efforts have included designing a desiccant cooling test laboratory, 

producing NREL’s solar industrial process heat design handbook, developing 

stretched-membrane parabolic dish solar concentrators, inventing a high-performance heat exchanger, and leading 

NREL’s low-cost solar collector effort. n

Larry Kazmerski proudly displays the new Silicon 

Cluster Tool at the Process Development and Integration 

Laboratory.

Helena Chum

Chuck Kutscher
	 2006 NRELResearchReview

2006 was a banner year for renewable energy and energy efficiency. The wind 

power industry installed a record 2,700 megawatts of new capacity, while the PV 

industry now has the capacity to produce more than 1,000 megawatts of solar cells 

per year and is continuing its rapid expansion. Geothermal energy and concentrating solar power are also experiencing a renaissance.

Renewable fuels grew at a record pace, as well; the ethanol fuel industry produced 

about 5 billion gallons of ethanol, an increase of about 28% in just one year, while 

new projects are expected to double that capacity by mid-2008. Likewise, U.S. production of biodiesel tripled to 250 million gallons, and enough biodiesel production 

facilities were operating by year’s end to more than double that production level.

Energy-efficient technologies also posted significant gains in 2006, and with President George W. Bush’s declaration that “America is addicted to oil,” the greatest 

emphasis was on hybrid electric vehicles. Thanks in part to state and federal tax 

credits, roughly 130,000 hybrid vehicles were sold in the United States. Automakers also started rolling out vehicles with efficient six-speed transmissions, lighter 

engine components, and other fuel-efficient innovations.

However, these impressive gains were accompanied by signs that some clean energy technologies are reaching limits in their rates of growth. Constraints in the supply of silicon held back growth in the PV industry, and despite the industry’s rapid 

growth, some experts predict that the demand for solar cells will significantly exceed the supply through the 

end of this decade. Likewise, the expanded ethanol fuel industry is expected to consume 20% of next year’s 

corn production, an outlook that contributed to a boost in corn prices near the end of 2006. Despite the growing number of hybrid vehicles on the road, U.S. petroleum consumption is expected to continue increasing for 

the foreseeable future.

Looking toward the future, President Bush unveiled his Advanced Energy Initiative (AEI) during the 2006 State 

of the Union Address. The AEI aims to change the ways in which we fuel our vehicles and power our homes and 

businesses by accelerating our use of five renewable energy and energy efficiency technologies: advanced 

batteries, cellulosic ethanol, hydrogen, solar power, and wind power.

Advanced lithium-ion batteries would help to commercialize plug-in hybrid vehicles, which can be charged 

from a home power outlet and can run on all-electric power for up to 40 miles. This would allow most people 

to use little or no gasoline during commutes to and from work and limit their gasoline use on longer trips, 

providing an opportunity to significantly reduce the nation’s petroleum usage. Cellulosic ethanol draws on 

nonfood sources of biomass, such as trees, grasses, and agricultural wastes, and allows a large expansion in 

the production of ethanol fuel. And hydrogen vehicles present an opportunity to create a new hydrogen 

economy, which can be powered in part by renewable energy.

To advance solar energy technologies, the President launched the Solar America Initiative, which aims to make 

solar PV technologies cost-competitive with other forms of renewable electricity by 2015. And to boost the 

deployment of wind power throughout the country, the AEI emphasizes the development of new small-scale 

wind technologies to power homes and businesses in areas with low wind speeds.

This special section of the NREL Research Review examines how NREL is supporting the president’s initiatives 

through innovative research. NREL’s emphasis on translational science—scientific research conducted with 

industry goals in mind—is yielding significant advances in lithium-ion battery technologies, cellulosic ethanol, hydrogen production from sunlight, small wind turbines that capture low-speed winds, and new low-cost, 

high-efficiency solar cells. Through the research efforts highlighted here, plus many other related and ongoing 

efforts, NREL’s research is truly enabling the next clean energy revolution. n

Clean Energy’s Next Revolution

NREL’s research 

accelerates 

the President’s 

Advanced 

Energy Initiative
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 

Nanotechnology Promises 

PIX15026

Capacity Boost for Lithium-Ion 

Batteries

An NREL-funded effort to create metal 

oxide nanomaterials could significantly 

boost the capacity of today’s lithium-ion 

batteries, the leading contender in nextgeneration battery technology for plugin hybrid vehicles.

“With these new nanostructured materials, we’ve come close to achieving an 

energy storage capacity that is double 

the capacity of graphite, which is the 

commercially employed anode material,” says NREL Scientist Anne Dillon. 

“Furthermore, no degradation has been 

observed upon significant laboratory 

testing, indicating the films are very 

durable.”

Nanostructured materials, or nanomaterials, consist of particles on the scale of 

a billionth of a meter (a nanometer)—

hence the name. Dillon has been working with NREL Scientists Se-Hee Lee and 

Harv Mahan to make anodes for lithium-ion batteries using nanoparticles 

of molybdenum oxide. Over the past 

three years, the project has been funded 

through NREL discretionary funds, 

known as Laboratory Directed Research 

and Development funds.

The process starts with hot-wire chemical vapor deposition (CVD), a technique 

originally pioneered by NREL to deposit 

amorphous silicon films for solar cells, 

and subsequently adapted to deposit 

carbon nanotubes for a variety of applications. In this current adaptation of 

hot-wire CVD, a molybdenum filament 

is heated to a white-hot temperature, 

about 2000°C, inside a quartz tube filled 

mostly with argon, an inert gas.

Introducing a small amount of oxygen 

causes the surface of the filament to 

evaporate, resulting in nanoparticles of 

molybdenum oxide, which form in the 

gas phase and condense on the quartz 

surface as a powder. Once removed, 

this powder can then be suspended in 

a methanol solution, and when a voltage is applied to it, it will deposit in thin, 

porous films.

Because the oxide films are actually 

made of millions of tiny particles, they 

have a high surface area, which allows 

them to act extremely efficiently as an 

anode, or negative terminal, of a lithium-ion battery. The team plans to apply 

a similar approach to the battery’s positive terminal, or cathode.

“We’re going to develop other metal oxide materials for cathodes and hope to 

get a similar improvement in capacity,” 

says Dillon.

One advantage of the nanoparticle 

terminals is their sponge-like texture, 

which allows them to easily expand and 

contract. That creates the potential to 

build a solid-state lithium-ion battery, 

replacing the battery’s liquid electrolyte 

with a polymer.

As that polymer expands and contracts 

with temperature, the nanoparticle terminals could flex along with it; graphite, 

in contrast, is relatively brittle. The goal 

is to increase not only the energy capacity of the battery, but also the speed at 

which it can produce electricity, a factor 

known as its rate capability.

“If lithium-ion batteries are ever going 

to be used for plug-in hybrids, you need 

to improve the rate capability, and our 

nanostructured materials have shown a 

better rate,” says Dillon. n

Advanced Batteries

NREL Scientist Anne Dillon examines the 

hot-wire chemical deposition system, which 

produces metal oxide nanoparticles for use in 

lithium-ion batteries.
	 	 2006 NRELResearchReview PIX01470

NREL Shoots for the Sun with New 

Photovoltaic Technologies

NREL is aiming for new solar power 

technologies that will significantly reduce the cost of solar electricity. What 

those technologies will be is anyone’s 

guess, but the odds are good that NREL 

will have a hand in them.

“Some people think the thin-film approach is going to be ‘the thing’ of the 

future,” says Researcher Supervisor 

Sarah Kurtz, “while others see great 

promise in organic solar cells and nanotechnologies. Meanwhile, researchers 

developing thinner silicon solar cells 

say ‘don’t bet against silicon,’ because 

silicon is always the king. And other 

people are saying the concentrator 

approach has real potential.”

The Concentrator Approach: 

A 40%-Efficient Solar Cell

Kurtz is likely part of that latter group, 

because she and Scientist Jerry Olson 

played a key role in developing multijunction solar cells, which have now 

achieved a 40% conversion efficiency. 

In other words, 40% of the sunlight hitting the solar cell is converted into electricity. The achievement by Spectrolab, 

a Boeing Company subsidiary, involved 

concentrating sunlight onto a triplejunction solar cell, which produced a 

world-record efficiency of 40.7%.

Such solar cells are much more expensive than today’s silicon solar cells, but 

their high efficiency can help to offset 

the high cost. The cells use sunlight that 

is concentrated by mirrors or a plastic 

Fresnel lens, a design that requires a 

tracking device to keep the solar concentrators pointed toward the sun. For 

such concentrating solar cells, the level 

of concentration is generally referred 

Solar Power

NREL researchers often employ molecular beam epitaxy to build 

multi-junction solar cells. Within the vacuum chamber shown 

here, solar cell materials are heated until they begin to evaporate. 

They are then condensed onto a substrate in a controlled process, 

resulting in ordered crystalline layers of semiconductor materials.

Clean Energy’s Next Revolution
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	  PIX15025

to as the number of suns: “100 suns” is 

sunlight concentrated 100-fold. While 

the tracking device adds to the cost, a 

100-sun concentrator only needs one 

square centimeter of solar cell material 

for every 100 square centimeters of collector area.

Through a combination of basic and 

applied research into the properties of 

semiconductor materials and devices, 

Kurtz and Olson advanced the concept 

of the two-junction solar cell—which 

places two layers of PV material atop 

one another—by developing a highefficiency cell and bringing it to commercialization. With NREL’s participation, 

Spectrolab and others extended that 

concept to a triple-junction cell, which 

consists of three layers of PV material. 

Each of the three materials captures 

a separate portion of the solar spectrum—this is known as the material’s 

bandgap—and the aim is to capture as 

much of the solar spectrum in the three 

layers as possible. But that’s not easy.

Traditionally, one difficulty in picking 

materials with the right bandgap is that 

the separate layers should also have 

similar crystal structures, in which the 

atoms are spaced the same distance 

apart. That equal lattice constant keeps 

the solar cell from suffering from fatal 

defects and poor bonds when the crystals don’t line up well with each other 

in the interface between the layers. 

Unfortunately, limiting the solar cells to 

materials with the same lattice constant 

ultimately limits their efficiency.

A relatively new approach is the metamorphic or mismatched lattice solar cell, 

which combines materials with different lattice constants. To avoid problems 

with defects and poor bonding, these 

solar cells employ an inactive transitional layer that gradually shifts from one 

lattice constant to another. The transition is made by steadily changing the 

percentage of one material in the transitional layer as it is grown. Working under 

NREL’s 

High-Performance 

Photovoltaic Program, Spectrolab used this approach to create its 

record-breaking cell.

“The real challenge,” says Kurtz, “is to 

implement those bandgaps in a monolithic structure that’s grown continuously, step-by-step, with materials of 

near perfect quality. You have to control 

thousands of little details all at once to 

hit that champion efficiency.”

Metamorphic materials can be used in a 

wide variety of cell configurations, such 

as in the inverted solar cell approach 

that has been studied by both NREL and 

Spectrolab. In this approach, the cell 

is built upside down, laying down the 

top layer first on a substrate and adding 

the bottom layer last. The solar cell is 

then removed from the substrate it was 

grown on and can be applied to a material of choice. NREL Scientist Mark Wanlass was one of the first researchers to 

achieve high efficiencies in an inverted 

solar cell, as described in detail in the 

2005 NREL Research Review. NREL’s solar 

cell has already achieved an efficiency of 

37.9% at 10 suns, but computer models 

suggest the cell, once perfected, could 

achieve an efficiency of 43% or higher at 

500 suns.

“The inverted cell has a higher performance potential, and excellent cost and 

engineering advantages,” 

says Wanlass. “For one thing, 

the original high-cost substrate 

is removed and can be reused, and 

the resulting ultra-thin tandem cell can 

be mounted on a desired supporting 

substrate. The supporting substrate can 

be engineered to address the needs of 

a particular application, such as flexible, 

ultra-lightweight cells for space, or robust, thermally conductive cells for terrestrial concentrators.”

Meanwhile, NREL is working to develop 

a 50%-efficient cell, a goal that Kurtz 

sees as achievable.

“The ways to get closer to 50% are twofold,” says Kurtz. “One way is to adjust 

the bandgap choices to come closer to 

optimal values, while still retaining very 

high perfection in the materials. The 

second approach is to add more junctions—again, with optimally chosen 

bandgaps—while maintaining perfection in the materials.”

The Low-Cost Approach: Plastic, 

Nanotechnology, and Printed 

Solar Cells

While Kurtz, Olson, and Wanlass pursue 

the high-efficiency route, another group 

of NREL researchers are taking the opposite approach: produce a solar cell as 

cheaply as possible, because even if it 

has a low conversion efficiency, it will still 

NREL’s polymer solar cells consist of small plastic 

squares of varying colors, with metal contacts for 

making electrical connections.
10	 2006 NRELResearchReview PIX15024

be a low-cost way to produce electricity.

Scientist Sean Shaheen is leading an 

NREL effort to produce inexpensive 

solar cells made from plastics that can 

conduct electricity. These organic solar 

cells function differently than standard 

solar cells do, generating an exciton—a 

bound pair of an electron and a positively charged hole—that migrates to 

a nearby boundary and then separates, 

yielding free charges than can produce 

electrical current. Excitons won’t migrate far, though, so these organic solar 

cells require the engineering of structures with features that are typically on 

the order of only tens of nanometers 

(billionths of a meter) thick.

NREL has been working with Konarka 

Technologies to create inexpensive 

plastic solar cells with conversion 

efficiencies exceeding 5%, which is high 

for plastic solar cells. The trick is to incorporate small nanometer-sized particles 

into the plastic. So-called buckyballs 

or fullerenes—nanoscale soccer balls 

made of carbon atoms—act as sites 

where excitons can separate into charge 

carriers.

NREL researchers are also investigating 

a number of analogous approaches to 

increasing the efficiency of plastic solar 

cells, such as embedding the polymer in 

a porous semiconductor film, impregnating the polymer with nanofibers 

of zinc oxide, or using polymers that 

branch out in a tree-like shape, called 

dendrimers.

Another way to cut solar cell costs is 

to fabricate them quickly and cheaply. 

Research Supervisor David Ginley has 

been working with HelioVolt Corporation to adapt ink-jet printing techniques 

to quickly deposit thin films of copper 

indium gallium selenide, a strong contender among thin-film solar cells. NREL 

has also employed ink jet printers to 

quickly apply metallic contacts to a 

range of solar cell materials. n

William Rance, a graduate student at the Colorado 

School of Mines, inserts a tray of polymer solar cells 

into a high-vacuum deposition chamber, where 

metal contacts are deposited onto the solar cells.

Clean Energy’s Next Revolution
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 11

PIX015047

NRELLaunchesProcess

Development

andIntegration

Laboratory

It’s all about the vacuum. 

The 11,400-square-foot Process 

Development and Integration 

Laboratory (PDIL) in NREL’s 

new Science and Technology 

Facility is a masterpiece in vacuum technology, featuring a 

variety of vacuum chambers 

and robotic sample handlers 

that keep thin-film solar cell 

samples isolated not only from 

dust but also from oxygen and 

other reactants in the air.

“Once the sample is initially 

introduced to the vacuum, it 

never sees air again until you’re 

done with it,” says NREL Scientist Brent Nelson, the process integration project leader.

Although the laboratory equipment is just starting to arrive in the massive laboratory space, one instrument completed in late 2006 and slated to arrive at NREL in early 2007 is indicative of the vision for the PDIL. 

Called the silicon cluster tool, it features a central vacuum robot that shuttles samples between eight surrounding vacuum chambers, where layers of silicon and transparent zinc oxides can be applied, as well as 

etching and passivation treatments. Scientist Qi Wang in NREL’s Silicon Group will be the principal operator 

for the tool, which will be used to fabricate amorphous silicon solar cells and to passivate silicon wafers in 

support of thin crystalline-silicon solar cells.

The cluster tool features several combinatorial chambers that will allow researchers to lay down 10 strips 

of material with different properties in both the horizontal and vertical directions, resulting in a 10-by10 grid that provides 100 different combinations on one 6-inch-by-6-inch sample. Those chambers allow 

researchers to more quickly explore different parameters to find the optimal combinations, an approach 

often referred to as high-throughput research.

At any point in the process, a vacuum chamber containing a sample can be wheeled away to an analytical 

instrument or even to an entirely different cluster tool. Only a handful of places in the world employ such 

inter-tool transport while maintaining a vacuum in the chamber, and most of those are for small samples; 

NREL may be the only place in the world employing such tool integration with such large samples. The 

vacuum chambers made it unnecessary to build a clean room, which in turn would have made the PDIL a 

much more expensive facility. They also allow several different thin-film technologies to share one set of 

expensive analytical tools.

The idea is actually borrowed from the semiconductor industry, in which plastic boxes containing clean 

dry air are used to transfer semiconductor samples without exposing them to dust particles. The PDIL just 

takes the concept a step further by protecting samples from molecular level contamination; vastly reducing material reaction with molecules found in the air, such as water vapor and oxygen. The concept was first 

championed by NREL Group Manager Peter Sheldon in a technical paper published back in 2000.

The first cluster tool to be installed in the PDIL is for amorphous and crystalline silicon solar cells. However, 

the build-out plan for the laboratory includes characterization tools and similar cluster tools for solar cells 

made from cadmium telluride, copper indium diselenide, polymers, and nanomaterials. n

The silicon cluster tool, which allows for robotic manipulation of silicon solar 

cells in a vacuum environment, was the first addition to the new PDIL.
12	 2006 NRELResearchReview PIX15105

NREL Laboratory Aims to Break Down Nature’s Defenses

Plants have evolved to be able to defend themselves against a wide variety 

of insect, fungal, and bacterial attackers. Although the attacking armies come 

equipped with a variety of enzymes that try to weaken a plant’s defenses, the 

plants have quite a few tricks of their own up their sleeves.

Grasses and tree barks, for instance, have an outside rind consisting of a waxy barrier and densely packed cells. The plants’ cell walls are made of highly crystalline 

cellulose, a material generally resistant to enzymes, and a coating of hemicellulose 

and lignin, which protects the cellulose from microbes. While cellulose and hemicellulose are both carbohydrates, lignin is a water-resistant polymer that also helps 

form the vascular channels within the plant.

All these components work together to form a strong defense for grasses, trees, 

and the inedible parts of agricultural crops, which scientists refer to as lignocellulosic biomass. But these same defenses make it difficult to free the sugars from 

within the biomass and allow them to be converted to fuels such as ethanol.

Cellulosic Ethanol

Scientists refer to the resistance of lignocellulosic biomass to being broken 

down as biomass recalcitrance. NREL 

and its industrial partners have discovered ways to get past plants’ defenses, 

for instance, by using heat, pressure, and 

dilute acid to break down hemicellulose 

into its component sugars. A cocktail of 

three enzymes can then convert the cellulose into glucose molecules, in a process known as hydrolysis.

Despite these approaches, the general 

problem of recalcitrance of the plants 

has not been overcome. For instance, 

two batches of cornstalks and leaves 

might appear the same, but will react 

much differently to such acid pretreatments and hydrolysis steps. Clearly, a 

greater understanding of the structure 

of these plants is needed to understand 

what makes some plants more resistant 

to chemicals and enzymes than others.

To address these issues, NREL has 

launched the new Biomass Surface 

Characterization Laboratory (BSCL). The 

BSCL is well equipped with imaging 

tools to help NREL scientists understand 

the structure of plants. The instruments 

include a scanning electron microscope 

for high-power images; an atomic force 

microscope to study cell wall surfaces; 

a transmission electron microscope 

to reveal internal structures and their 

chemistry; a near-field scanning optical 

microscope, which can perform spectroscopic analysis of surfaces and focus 

on single molecules; and a confocal microscope, which can yield three-dimensional images of samples.

Launched in 2005, the BSCL has already 

yielded insights into biomass recalcitrance. By studying the pretreatment 

processes used to break down the hemicellulose and remove the lignin, the 

BSCL revealed that some of the hemicellulose is converted directly into sugars, 

while the hemicellulose that is linked to 

lignin is carried into the solution. That 

means that, for plants in which most of 

The thermal pretreatment of lignocellulosic biomass 

disperses the glue-like lignin into droplets of varying sizes. 

In this false-color image from NREL’s Biomass Surface 

Characterization Laboratory, the lignin droplets, shown in 

orange, range from 50 to 10,000 nanometers in diameter.

Clean Energy’s Next Revolution
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 13

the hemicellulose is linked to lignin, a 

low percentage of that hemicellulose 

will be broken down into sugar, so less 

fuel will ultimately be generated from 

the biomass.

NREL is also attacking the problem from 

a different angle, trying to better understand the enzymes that break down 

cellulose. Called cellulases, the enzyme 

complexes actually consist of a collection of protein enzymes, and each one 

plays a role in breaking down cellulose 

to glucose molecules.

To understand how cellulases work, 

NREL is employing CHARMM (Chemistry 

at Harvard Molecular Mechanics), a software model for simulating the actions of 

large molecules. The NREL simulations 

include roughly one million atoms to 

model the enzyme, the cellulose, and 

the surrounding water simultaneously. 

If that’s not enough, NREL needs to run 

the model for 25 million steps that will 

equal 50 billionths of a second, making 

it the largest biological computer model 

yet attempted.

To extend the CHARMM model to such 

a huge problem, NREL researchers and 

their partners at the Colorado School 

of Mines and Cornell University have 

teamed up with software developers 

at The Scripps Research Institute and 

with computational scientists at the San 

Diego Supercomputer Center at the 

University of California, San Diego. One 

solution is to run parts of the CHARMM 

model in parallel to speed the computations.

The computer model is expected to answer questions about how the cellulase 

enzyme complex interacts with cellulose; one such question is whether the 

enzyme acts on only one face of the cellulose crystal. Water is also an important 

part of the equation, because it forms a 

high-density layer on the surface of cellulose. Understanding how the cellulase 

complex disrupts that water layer may 

be key to understanding its function. n

NREL Scientist Maria Ghirardi has billions of factories churning out their 

products in support of her research. Her 

helpers are very small, though: they are 

tiny cellular factories of E. coli bacterium, busily manufacturing the hydrogenase enzyme that could be the key 

to producing hydrogen from sunlight. 

Such a process could one day provide 

a renewable energy source for fueling 

future hydrogen vehicles.

Scientists have long known that under 

some conditions, the green alga Chlamydomonas reinhardtii would produce 

hydrogen. The enzyme at the heart of 

this hydrogen-producing process is 

called hydrogenase, and it has a unique 

ability to combine protons and electrons to form a hydrogen molecule. 

Because photosynthesis—the process 

that plants use to convert sunlight to 

chemical energy—also generates a 

lot of electrons, scientists see a potential for combining photosynthesis with 

hydrogenases to generate hydrogen 

from sunlight.

But there’s a big problem: photosynthesis also generates oxygen, and most 

hydrogenases can’t tolerate oxygen. 

So the key to the process is to find a 

hydrogenase enzyme that tolerates 

oxygen and is still very active, churning 

out lots of hydrogen.

Back in 2000, Ghirardi and NREL Research Fellow Mike Seibert joined researchers from the University of California, Berkeley, to announce that they had 

found the key to forcing Chlamydomonas to produce the energy-rich gas: they 

deprived it of sulfur. This approach—

based on an understanding of the alga’s 

metabolism garnered through years of 

research—decreased the alga’s internal production of oxygen and caused 

it to consume any oxygen produced by 

photosynthesis.

Hydrogen

In the absence of net oxygen, the alga 

reverted to an alternate metabolic 

pathway, which generated hydrogen 

through the degradation of starch and 

through the photosynthetic oxidation 

of water. The process works, but the 

photosynthetic process yielded low 

amounts of hydrogen. In order to fully 

utilize the available sunlight for hydrogen production, the research team realized that they needed to find or engineer a hydrogenase that functions well 

in the presence of oxygen.

“There are a few hydrogenases in nature 

that are more tolerant to oxygen, but 

they’re not found, so far, in photosynthetic organisms,” says Ghirardi. “Why is 

that important? Because in photosynthetic organisms, you can get hydrogen 

directly from water, and in non-photosynthetic organisms, you have to feed 

them some carbon source, so it’s not as 

economically desirable.”

A major problem that NREL researchers faced was the lack of a simple way to 

study and engineer algal hydrogenases. 

The hydrogenase consists of a metallic catalytic cluster bound to a protein 

structure, and earlier attempts to insert 

the hydrogenase genes into E. coli, an 

organism commonly used for such purposes, yielded inactive enzymes that 

lacked the critical metallic cluster.

That all changed in 2005, when Ghirardi and Research Associate Matthew 

Posewitz were studying the green alga 

Chlamydomonas by creating random 

mutations in its genome. Using a process called insertional mutagenesis, the 

researchers inserted pieces of DNA at 

random on the alga’s genome to disrupt 

genes.

“We looked for the mutants that could 

not produce hydrogen, and among the 

ones that we found was this particular 

Cellular “Factories” Aid Search for Key to Converting Sunlight to Hydrogen
14	 2006 NRELResearchReview PIX15031

produce large amounts of hydrogenase, 

making it much easier to study. The researchers can mutate the hydrogenase 

genes, insert them into the E. coli, and 

see how they behave in terms of oxygen 

tolerance and hydrogen production.

“This has had a major impact in the field 

of hydrogenases and hydrogen production,” Ghirardi says.

So far, Ghirardi’s team has used the E. 

coli to examine the oxygen tolerance 

of a hydrogenase found in the Clostridium bacterium. King suspected that an 

unusual appendage on the Clostridium 

hydrogenase was the key to its oxygen 

tolerance. Lopping off the appendage, 

he inserted the truncated enzyme into 

E. coli. He hoped the altered enzyme 

would lack the oxygen tolerance, but 

such was not the case.

“We learned something from it,” says 

Ghirardi, “but I wish the result had been 

the other way around.”

The team is in the process of developing new methods to study oxygen 

tolerance in hydrogenases, using both 

random mutations and intentional 

ones. The work is being aided by a fruitful collaboration with computational 

scientists at NREL and at the Beckman 

Institute. These scientists are employing 

computer simulations to map possible 

pathways by which oxygen can access 

the catalytic site of the hydrogenase 

enzyme and inactivate it. By mutating 

the hydrogenase into a form that blocks 

those pathways, Ghirardi’s team hopes 

to find the key to an oxygen-tolerant 

hydrogenase.

“Such mutations could allow us to 

engineer an organism that efficiently 

produces hydrogen through photosynthesis,” says Ghirardi. “And once we 

fully understand the process, perhaps 

we can move beyond the organism, 

and create an entirely synthetic photochemical pathway for producing hydrogen from sunlight in vitro.” n

mutant that was disrupted in a gene that nobody knew anything about,” says Ghirardi. 

“It was called a HydEF gene. It turns out that this gene product is responsible for assembling the catalytic structure of the hydrogenase. We found not only this gene, but 

another adjacent gene to it in the genome, and together they function to put together the metallic catalytic cluster in the hydrogenase.

“Now we can not only transform the E. coli with the hydrogenase gene, but also with 

the assembly genes. So E. coli makes the structural protein, but it’s also able to make 

the catalytic cluster and assemble it into the hydrogenase.”

NREL Scientist Paul King was the first to demonstrate the gene insertions into E. coli, 

a breakthrough that allowed the research team to conscript the E. coli bacterium to 

Paul King purifies biological catalysts for 

hydrogen production using fast protein liquid 

chromatography within an oxygen-free chamber.

Clean Energy’s Next Revolution
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 15

PIX15030 

Award-Winning Wind Turbine Demonstrates a Successful NREL 

Collaboration

A cost-shared subcontract between NREL and Southwest Windpower has resulted 

in a small wind turbine that begins producing power at a lower wind speed than 

most wind turbines: only 7 miles per hour. The innovative Skystream 3.7 wind turbine 

earned a 2006 Best of What’s New Award from Popular Science magazine and was 

recognized by Time Magazine as one of the “Best Inventions 2006.” NREL started working with Southwest Windpower back in 2001, and the company took full advantage of 

the working relationship.

“They wanted to come out and pick our brains on a regular basis,” says Project Leader 

Trudy Forsyth. “We were more closely involved with their design than we have been 

with anyone else. It was really rewarding for our technical staff, because they love 

to get into the technical details. And it was rewarding for Southwest Windpower, 

because they used NREL as their brain trust, which is a perfect role for us.”

The 1.8-kilowatt wind turbine is quieter than most, drawing on acoustics research performed by NREL researcher Paul Migliore, who is now retired. That research called for 

a lower rotating speed and for blades with a blunt leading edge and a sharp, thin trailing edge. The turbine also employs NREL airfoils—developed by another NREL retiree, 

Jim Tangler—that are insensitive to roughness caused by dirt or bugs building up on 

the blades, and that yield a high energy capture for the turbine blades.

In addition, it draws on an idea conceived by Forsyth and NREL Engineer Ed Muljadi to use 

the turbine’s generator to cause it to stall at high wind speeds. Combined with the turbine’s downwind design, that approach simplifies the turbine, avoiding the need for a tail 

vane. NREL Project Leader Jim Green coordinated NREL’s research support for the project.

David Calley, the president of Southwest Windpower, contributed another 

key innovation: the turbine uses a 

high-efficiency permanent magnet 

generator with a unique slotless stator. 

While most generators tend to stick or 

cog at a position where the rotating 

magnet aligns with one of the magnetic 

poles or slots in the stator, the slotless 

stator avoids cogging, allowing the 

generator to start turning at lower wind 

speeds.

Yet another innovation is the turbine’s 

integrated electrical design. Southwest 

Windpower specifically designed the 

electrical characteristics of its generator 

to take advantage of the turbine’s builtin power inverter, which delivers alternating current to the home. The electrical design avoids the energy losses that 

are common in such small wind turbines 

and delivers a higher system efficiency 

than most small wind turbines on the 

market.

The company is placing heavy emphasis on the “plug and play” characteristics 

of the Skystream turbine, which is designed for the suburban market. And to 

meet that market, the standard product 

offering is to mount the wind turbine on 

a 10-meter tower, which is a lower tower 

than many experts would consider ideal.

“For most of the United States, there are 

regulations that typically only allow you 

to put up about a 10-meter tower without getting zoning approval,” says Forsyth. “Even though the wind resource is 

not ideal at that hub height, Southwest 

Windpower is banking on the fact that 

avoiding zoning approval will help them 

market and sell their turbine.”

Forsyth also sees the company as having 

the ability to supply a large market with 

its turbine.

“They’ve been achieving high-volume 

wind turbine manufacturing for years—

10 to 13 thousand per year—and they’ll 

do that with the Skystream, as well,” says 

Forsyth. n

Wind Power

The Skystream 3.7 is a small wind turbine 

engineered to quietly and efficiently produce power 

from low-speed winds. The turbine was designed by 

Southwest Windpower with help from NREL.
16	 2006 NRELResearchReview PIX15032 

WinDS of Change

An NREL computer model shows us how and where to use 

the wind energy systems of the future, and more.

At NREL, as in other research centers, every scientific discovery starts out as a theory. 

But before that theory can be tested, one R&D process is necessary to make sure the 

glimmer in the theorist’s eye is even feasible: analysis.

NREL’s strategic energy analysis capability is one of the laboratory’s core competencies and a must-have element of every technology development process. But because 

analyses are often only as good as the tools the analysts have to work with, key models need to be designed to produce credible, reliable analyses that support NREL’s 

research.

NREL analysts Walter Short (left) and Nate Blair are 

the originators of WinDS, a software tool for modeling 

the deployment of wind power technologies.
Wind Capacity Total 

Installed (2030) (GW)

0.0-0.1

0.1-1

1-5

5-10

10-20

>20

Projected Wind Power Capacity by State in 2030

	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 17

An analysis model starts with a software capability carefully programmed 

to make use of various inputs to produce a variety of outputs. Although 

many good energy models exist that 

different analysts and organizations 

use throughout the world, customized 

models are often required to meet individual researchers’ needs. NREL discovered such a need while preparing to expand research in wind resources and to 

examine how to increase the amount 

of installed wind power capacity in the 

United States.

Starting with a Spreadsheet

What started out as a spreadsheet on 

one analyst’s laptop has become one of 

the most credible models for projecting wind power capacities and energy 

deliveries for the future, and it has a 

name to match: the Wind Deployment 

System, or WinDS.

The WinDS concept became reality in 

2001 when NREL’s Wind Technologies 

Program requested an analysis of the 

feasibility of low-speed wind turbines 

in the United States by evaluating load 

and transmission requirements. NREL’s 

Walter Short, a group manager in 

NREL’s Strategic Energy Analysis Center, 

started with a simple spreadsheet 

model that drew on the geographic 

information systems expertise of NREL 

Scientist Donna Heimiller.

Short then took the spreadsheet and 

spent countless hours, along with an 

intern from the Colorado School of 

Mines, to develop the first version of 

WinDS. The model was able to find the 

optimal value for wind power capacity 

based on the wind resource, the available transmission lines, and the electrical load requirements. Short was soon 

joined in the effort by NREL Analyst 

Nate Blair, who provided his insights 

based on other analysis tools, while 

Heimiller helped to beef up the geographic aspects of the model.

The result was a new model unique in 

its ability to “regionalize.” The model 

provides a solid, detailed analysis of 

wind that goes far beyond more simplistic models that consider only a few 

regions in the United States. The new 

regionalization capability makes it possible to evaluate numerous site-specific 

wind resources.

“The modeling capability provided 

by WinDS is unique in the field,” says 

Bobi Garrett, NREL associate director 

for Strategic Development and Analysis. “The major national models cannot 

deal with the wide variation in regional 

energy resources, demand, policy, or 

physical infrastructure.”

In developing WinDS, NREL sought 

significant input from a variety of wind 

industry professionals and other relevant researchers. Short took a direct 

approach, determining what characteristics would be important to capture—

such as transmission access and wind 

resource variability. Taking all these 

things into consideration, he applied 

them to all 358 regions designated in 

the model.

After further testing and expansion, 

Short began demonstrating WinDS for 

other labs. As word got out, nonprofit 

groups and industry representatives 

alike became interested in applying the 

WinDS model to their analysis work.

Enabling a National Action Plan

WinDS’ regionalization capability is 

what distinguishes it from other models, 

such as the National Energy Modeling 

System. Most capacity expansion models do not have significant geographic 

capabilities and so cannot track the geographic dispersion of the installed wind 

energy or estimate transmission costs as 

penetration levels increase.

WinDS considers key market issues 

such as transmission system access and 

cost as well as the reliability of the wind 

resource. It can determine variability 

in wind output over time and consider 

inputs for ancillary service requirements 

and costs for the 358 individual regions. 

The model estimates the market potential of wind energy in the United States 

for the next 20 to 50 years under different technology development and policy 

scenarios, and it has already yielded 

important insights.

WinDS’ innovative approach to modeling the potential deployment of wind 

energy addresses many of the shortcomings of large national energy models’ representation of the competitive 

potential of wind energy.

“Many national models rely on assumptions and oversimplify wind energy,” 

says NREL Project Leader Brian Parsons, 

who works in NREL’s Wind Technologies 

The WinDS model can examine where wind power will be developed under various scenarios. In 

this example, which shows one scenario for achieving 20% wind power by 2030, much of the wind 

power capacity is concentrated in the U.S. heartland.
2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022 2024 2026 2028 2030

1600

1400

1200

1000

800

600

400

200

0

Total Wind (GW)

Hydro

Nuclear

Gas-CC

Gas-CT

Oil-gas-steam

Coal-IGCC

Coal-new

Coal-w/scrub

Coal-no scrub

Cumulative Installed Capacity (GW)

Year

Projected Generating Capacity by Fuel Type

18	 2006 NRELResearchReview

Program. “This model’s attention to detail has ensured accuracy in characterizing technologies and credibility for 

these numbers.”

After President George W. Bush called 

for producing 20% of the nation’s electricity from wind power by 2030, the 

American Wind Energy Association 

(AWEA) partnered with DOE and other 

stakeholders to develop a wind resource 

action plan. The plan required an analysis of the benefits of, and barriers to, 

wind production, as well as where transmission would be needed, an analysis 

that WinDS was able to provide in detail. 

Using WinDS, the team is analyzing the 

feasibility and economics of reaching 

the 20% goal.

“Wind industry and policymakers are 

very interested in knowing how much 

U.S. electricity can come from wind, 

and the WinDS model has proven to be 

an indispensable tool to evaluate this 

question,” says Rob Gramlich, AWEA 

policy director. “We have learned a great 

deal from the model thus far and look 

forward to sharing these results with 

policymakers and the energy industry 

this spring.”

NREL has demonstrated WinDS’ ability to answer important deployment 

questions, highlighting transmission 

possibilities and where resources need 

to be built. For instance, WinDs uses the 

358 regions in its system to show the 

locations of cumulative wind-power 

installations needed in 2050 under certain scenarios. As expected, the results 

show the installations located in areas 

with excellent wind resources. However, 

WinDS also shows how it makes sense 

to locate installations close to major 

load centers, such as in southern California.

Addressing Specific Markets 

and Issues

Another practical application of WinDS 

was an analysis done in 2006 to evaluate the market impacts of specific 

state-level policies. The analysis looked 

at national and regional wind energy 

deployment and generation through 

2050 and examined impacts on wind 

growth associated with state-level 

renewable portfolio standards (RPS). 

These standards require utilities to 

generate a certain percentage of their 

electricity from renewable energy resources, and wind power is currently the 

preferred choice. The analysis examined 

the effects of increased penalties for failing to meet the RPS requirements and 

also examined other mandates and tax 

credits.

“The analysis showed that these mandates increase industry size and lower 

costs, which results in wind capacity 

increases in states without the rules, and 

greater market growth even after the 

policies expire,” says Blair. “Although the 

policies are enacted by individual states, 

the cumulative effect must be examined 

at a national level.”

Another WinDS analysis examined several potential energy policy cases and 

how they could affect the U.S. market for 

wind power, including issues related to 

the penetration of wind energy technologies into the electricity sector. Principal 

market issues analyzed included access 

to and cost of transmission as well as variability. WinDS modeled the impact of various policy initiatives, including a wind 

production tax credit and an RPS.

The line for WinDS assistance doesn’t 

stop there. The Bureau of Land Management (BLM) also used WinDS outputs 

within their programmatic environmental impact statement for wind power on 

the public land that the BLM manages 

in western states. WinDS was used to 

forecast the amount of land in the West 

that could be economically developed. 

NREL has provided additional results to 

the National Research Council, General 

Electric, and other groups interested in 

the regional-level analysis provided by 

WinDS.

Modeling the Wind, and More

Success increases demand, and many 

people are hoping that WinDS will be 

able to do even more modeling in the 

near future. And NREL analysts have already applied WinDS’ unique system to 

models for other technologies, such as 

concentrating solar power and hydrogen.

“The capabilities of WinDS have raised 

The WinDS model can examine how wind power will compete with other generating technologies 

under various policy scenarios. This example shows one path toward achieving 20% wind power 

by 2030, and shows wind competing with a strong growth in natural gas combustion turbine and 

combined-cycle technologies. The projection shows coal power growing slightly as the industry 

shifts to cleaner technologies, like integrated gasification and combined-cycle plants, while the 

generating capacity from oil, nuclear, and hydropower sources declines.

WinDS of Change
2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022 2024 2026 2028 2030

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200

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Class 5

Class 4

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Wind Capacity (GW)

Year

Projected Wind Power Capacity by Wind Class

	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 19

some awareness within the modeling 

community of more sophisticated approaches to incorporating wind and other renewable energy technologies into 

their models,” says Sam Baldwin, chief 

technology officer in DOE’s Office of Energy Efficiency and Renewable Energy. 

“This innovative work also has been 

extended to hydrogen and solar and is 

already having a fundamental impact on 

understanding the potential of renewable energy in the broader market.”

For example, the Hydrogen Deployment 

System, or HyDS, model looks at U.S. 

market expansion of hydrogen production from wind and other sources over 

the next 50 years, evaluating future 

roles and contributions. With the current 

emphasis on production, it is important 

to look at the feasibility of producing hydrogen from three competing technologies: wind, steam methane reforming, 

and distributed electrolysis powered 

by electricity from the grid. The model 

has to consider the interconnection 

between wind and hydrogen as well as 

hydrogen storage and transportation 

issues. The resulting data are helping to 

shape DOE’s R&D approach.

WinDS can also measure the interaction between electric and transportation technologies, such as analyzing 

the benefits of plug-in hybrid-electric 

vehicles (PHEVs). A PHEV can recharge 

its batteries with electricity from the 

electric utility grid. The vehicle can then 

drive with less gasoline or other alternative liquid fuels such as biofuels or hydrogen. PHEVs have recently emerged 

as a promising alternative for displacing 

a significant portion of fleet petroleum 

consumption.

Using WinDS, NREL analysts carried out 

a study of PHEVs that can be charged 

from or discharged to the grid. They 

found a synergism between PHEVs and 

wind energy, indicating that the electricity storage capacity of these vehicles 

can make a difference in the cost-effective wind capacity for the United States.

Finally, the WinDS model is being 

extended to other renewable electric 

technologies. The first of these is concentrating solar power, specifically, parabolic trough power plants equipped 

with six hours of thermal energy storage. Thanks to the lessons learned 

in constructing the wind features in 

WinDS, the extension of the model to 

concentrating solar power was relatively 

easy, and the new Concentrating Solar 

Deployment Systems model is already 

being put to good use.

WinDS of the Future

Although WinDS currently focuses exclusively on the electricity sector, future 

goals include examining electricity storage options, transmission power flows, 

carbon sequestration, energy storage, 

coal plant siting, and a full complement 

of renewable energy resources, including biomass, geothermal, and ocean energy. With such improvements, WinDS 

could be used to examine the synergies 

among renewable energy technologies and analyze such policies as climate 

change legislation or a national RPS.

One of the items at the top of many 

modelers’ wish lists—especially Short’s 

and Blair’s—is for analysts all over the 

world to put their model’s results to 

work in other analyses. To achieve that 

goal for WinDS, Short and Blair are currently refining a supply curve that can 

be used as an input into other models, 

providing a more sophisticated method of examining the transmission and 

variability issues associated with wind 

energy.

NREL is also working with modelers and 

analysts from a variety of organizations 

to examine the differences in various 

energy models. These experts, who 

have formed the Renewable Energy 

and Efficiency Modeling and Analysis 

Partnership, are conducting workshops 

to look at how outputs differ among 

the modelers in the group. By looking 

at these differences, they hope to create 

common scenarios for all models and 

improve their ability to evaluate policy 

decisions. And as these collaborative 

efforts grow, so does the laboratory’s 

reputation.

“What started out as a single model for a 

single technology has grown into a suite 

of leading-edge models,” Garrett says. 

“WinDS has taken NREL from a position of little recognition for its modeling 

ability to broad acknowledgment for a 

credible capability.” n

Assuming that the nation will reach 20% wind generation by 2030, this output from the WinDS 

model shows an increasing need to make use of class 3 and class 4 wind resources—considered 

“fair” to “good” resources—in the future, following significant near-term exploitation of the 

“superb” class 7 wind resources.
	 20	 2006 NRELResearchReview

Next-Generation Fuels—

What’s Old Is New Again

In the search for new biofuels, NREL is reviving its research into 

biomass pyrolysis and gasification, as well as techniques for 

converting algae into biodiesel.

Al Darzins has been at NREL for less than 2 years, but finds himself spending a lot 

of time these days looking at research results from some of the laboratory’s earliest research. As group manager for the National Bioenergy Center’s Applied Sciences Group, he is overseeing several “new” research efforts that build on some very 

old ones. His efforts are aimed at converting biomass—plants and plant-derived 

materials—into fuels.

“Previous biofuels work performed at NREL under various programs has provided a 

strong foundation for our current efforts to kick-start that research again, ten years 

later,” says Darzins.

When the laboratory first opened in 1977, the Arab Oil Embargo of 1974 was still fresh 

in people’s minds. Early research included several different potential technologies 

for making liquid transportation fuel from biomass. Some of those, while promising, 

were subsequently set aside to focus on other research.

Today, with reducing dependence on imported oil a high presidential priority, three 

of these technologies—the production of pyrolysis oil, liquefied synthesis gas, and 

microalgal oil—are once again attracting a lot of attention. Darzins and his NREL colleagues are excited about moving forward with them, taking advantage of both our 

past research efforts and of applying new research capabilities to them.

Borrowing a “Clean Coal” Technology for Ethanol Production

Coal was once the transportation fuel of choice for the United States, powering our 

trains and even fueling an early automobile, the Stanley Steamer. But liquids and gases burn faster than solids, have high energy densities, and are more convenient to use 

in vehicles, all of which are reasons why gasoline and diesel fuel became the dominant transportation fuels.

Because of these advantages, it can be well worth expending energy to convert solid 

fuels—whether they be biomass or coal—to liquids. By heating biomass to very high 

temperature with limited or no oxygen, researchers can either liquefy or gasify it. When biomass is liquefied, the resulting pyrolysis oil can be used as a feedstock for conventional oil refining. When it is gasified, 

the synthesis gas can be catalytically converted to liquid fuels that substitute well for diesel or gasoline.

In fact, the pyrolysis and gasification technologies used for converting biomass to liquids were initially applied to coal to produce petroleum substitutes. With a strong utility interest in integrated gasification and 

combined-cycle technologies for coal power (so-called “clean coal” technologies), gasifier technology has 

advanced significantly.

While the core technology has advanced, biomass pyrolysis and gasification are gaining renewed interest 

in part because of the emphasis on producing ethanol from cellulosic biomass, such as wood chips and 

plant leaves and stalks. Cellulosic biomass is made up of cellulose, hemicellulose, and lignin. Cellulose and 

hemicellulose are plant-derived, sugar-based polymers, and biological biomass conversion technology 

can ferment the sugars to ethanol. But lignin, the third major component of biomass—making up 15% to 

25% of biomass by weight—does not contain sugars.
Char Heat

Vapors

Combustion Gases (H2, C2, CH2, C2H2, C2H4)

Condensation

Liquids

Power 

Generation 

or Chemical 

Separation

Catalytic Conversion to 

Hydrogen (Optional)

Biomass

Pyrolysis

650°C

no O2

Biomass Liquefaction via Pyrolysis

	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 21

PIX12684

Until recently, NREL’s process designs for 

ethanol production called for burning 

the lignin to provide heat and power 

for the ethanol plant. But with transportation fuels as a top priority, the new 

thought is to use multiple technologies 

to produce fuels. Because thermochemical processing can produce fuels from 

any biomass source, not just sugars, 

researchers can use it to convert the lignin and any other residue from biological processing to additional ethanol or 

other liquid fuels within the same biorefinery.

Also, biological processing is currently 

focused on agricultural residues such as 

cornstalks and husks. Other biomass—

particularly softwoods, which may become extensively available from forest 

thinning operations—is more challenging for fermentation and may be more 

suitable for pyrolysis or gasification.

NREL Goes Full Circle on Pyrolysis 

Research

NREL’s research on biomass pyrolysis has 

returned to its roots. Pyrolysis involves 

liquefying biomass by first heating it to 

about 550oC in the absence of oxygen 

and then condensing the vapors. The 

resulting pyrolysis oil is a complex mixture analogous to crude oil (except that 

it contains oxygen) and can be burned 

as fuel or used as a feedstock for conventional oil refineries.

NREL’s original pyrolysis research had 

that direct product as its objective, but 

in the late 1980s, the laboratory turned 

its focus to making specific fuel additives or other petrochemicals from 

pyrolysis vapors before they condensed. 

NREL researchers worked on cracking the vapors to ethylene for gasoline 

production and then on catalytically 

converting them to aromatics and other 

liquid hydrocarbons.

In the 1990s, when Scientist Stefan 

Czernik joined NREL as a thermal and 

catalytic conversion specialist, the 

emphasis changed to producing chemical products other than fuels. One effort, 

for example, sought to develop wood 

adhesives from pyrolysis oil, a natural fit 

for reducing petrochemical use by an 

industry with ready access to biomass 

resources. Another effort sought to 

regenerate base chemicals for plastics 

production by pyrolyzing polymers, 

specifically from discarded carpeting. 

Now Czernik is heading up efforts to use 

Biomass pyrolysis involves heating the biomass to high 

temperature in the absence of oxygen. The process yields 

vapors that are condensed to form an oily liquid.

Biomass pyrolysis involves heating the biomass to high temperature in the absence 

of oxygen. The process yields vapors that are condensed to form an oily liquid.
Pyrolysis

650°C

no O2

Biomass Pyrolysis 

Vapors

Synthesis 

Gas

Ash & 

Exhaust 

Gases

Electricity

Tail 

Gas

Fuel 

Products

Steam 

Reformation 

850°C

Steam Boiler

Char & Ash

Heat

Exhaust Gas Turbine

Steam

Combustion

Steam

CO2 Removal Compressor Fischer-Tropsch 

Reactor

Biomass Gasification via Staged Steam Reformation with a Fluidized Bed Gasifier

	 22	 2006 NRELResearchReview

the whole pyrolysis oil along the lines of 

NREL’s original pyrolysis work.

“The goal is to make pyrolysis oil a standard petroleum refinery feedstock,” says 

Czernik.

One project is exploring the suitability of pyrolysis oil derived from lignin 

for such a feedstock. NREL produces 

the pyrolysis oil and research partners at DOE’s PNNL and UOP LLC, a 

private petroleum research company, 

hydrotreat it, that is, they upgrade it 

by removing impurities. Among other 

things, the process removes oxygen, 

which is the primary difference between 

pyrolysis oil and crude petroleum.

NREL is conducting techno-economic 

and life-cycle analyses of the biorefinery 

pathway involving lignin pyrolysis and 

hydrotreating to determine how profitable it will be, what kinds of energy and 

environmental impacts it would have, 

and what changes could be made to 

most effectively improve that profitability and impact.

A second project seeks to upgrade 

pyrolysis oil during its production by reIn the 1990s, syngas was envisioned primarily as a fuel for electrical power generation, with a focus first on large utility 

systems and then on smaller distributed 

generation systems. The shift from electricity production back to liquid fuels is 

in large measure a tribute to the great 

gains made by wind turbines, solar cells, 

and other renewable energy technologies for power generation. When it 

comes to liquid transportation fuels, 

however, biomass is the only renewable 

game in town.

Conversion of syngas to liquids also has 

a colorful and somewhat dark history. 

Franz Fischer and Hans Tropsch first 

studied conversion of syngas into larger, 

useful organic compounds in 1923. 

Using syngas made from coal and metal 

catalysts, they were able to produce liquid hydrocarbons. Fischer-Tropsch systems were used successfully in Germany 

during World War II and South Africa 

during apartheid embargoes when 

each faced limited oil supplies. Several 

commercial Fischer-Tropsch operations 

continue today, and the term Fischeracting either the condensed oil or the oil 

vapors with ethanol. Researchers expect 

this process to reduce the acidity of the 

pyrolysis oil and make it more stable, 

both of which would improve its suitability as an oil refinery feedstock.

Because of the potential for either 

hydrotreating or ethanol upgrading, or 

a combination of both, the future for 

pyrolysis oil appears bright.

“We think pyrolysis is a powerful technology and are eager to use it to help 

meet transportation fuel needs,” says 

Czernik.

The Three-Phase Approach to 

Fuels: From Solid to Gas to Liquid

Another approach to converting solid 

biomass into a liquid fuel is to first convert it into a gas. NREL scientists gasify 

biomass to a mixture of carbon monoxide and hydrogen known as synthesis 

gas or syngas by taking the pyrolysis 

process a step further, heating to about 

850oC with about one-third the oxygen 

needed for efficient combustion.

Biomass gasification is a multi-step process that starts with pyrolysis, followed by a high-temperature steam treatment that 

converts the pyrolysis products into a mixture of gases, called synthesis gas. After a treatment step, the gas is compressed and 

fed into a catalytic reactor to produce a liquid fuel. A byproduct from the process can be used to generate electricity.

Next-Generation Fuels—What’s Old Is New Again
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 23

PIX15033

Tropsch has come to be applied to any 

catalytic conversion of syngas to liquid 

fuel.

The NREL syngas-to-liquid system bubbles the gas through an oil slurry under 

high pressure, with the catalyst suspended in the liquid. While traditional 

Fischer-Tropsch processes seek to produce non-oxygenated hydrocarbons, 

NREL’s objective is to produce ethanol or 

perhaps “higher alcohols”—a mixture of 

ethanol and larger-molecule alcohols.

“The process is similar to FischerTropsch or methanol reformation,” says 

NREL Scientist Steve Deutch, “but we 

stop it at an earlier stage.”

Producing ethanol from syngas would 

be an ideal companion technology for a 

biorefinery that ferments biomass into 

ethanol because the syngas process 

would produce ethanol from material that cannot be fermented, such as 

lignin. Because both processes would 

produce ethanol, the approach would 

avoid the need for additional infrastructure to deliver another product, such as 

a lignin-derived chemical.

NREL is currently working with DOE’s 

PNNL on a joint effort to produce alcohols from syngas. PNNL is working 

to improve the catalyst, while NREL is 

focusing on improving the process conditions and testing the catalyst and process against a wide range of operating 

conditions, using actual syngas derived 

from biomass.

Microalgal Lipids—An Aquatic 

Approach to Future Fuels

Yet another early biofuel research area 

that is back in the spotlight is the conversion of algae to fuels. Although small 

in size compared to cellulosic ethanol 

efforts, the NREL research effort on fuels 

from algae involved extensive research 

through the 1980s and early 1990s. 

NREL’s biomass researchers led the way 

in developing technology for growing 

NewLabProvidesPowerful Toolsfor

BiocatalystDevelopment

Be it microscopic algae for oil production, fungi for enzyme production or 

yeast or bacteria for sugar fermentation, the advanced biological technology 

for converting biomass to fuel is all about developing organisms that produce 

better biochemical agents or better perform desired functions themselves. 

NREL’s bioconversion research capabilities have been greatly enhanced by 

opening of a major new facility. Applied Sciences Group Manager Al Darzins 

says the new Systems Biology Laboratory has three main components.

“New X-ray crystallography equipment allows us to determine the threedimensional structure of enzymes, a key parameter required in understanding how they work,” says Darzins. “This information also allows us to make 

them perform better. High-throughput robotics capabilities allow us to rapidly test large numbers of genetic variants or simultaneously conduct hundreds and even thousands of ‘miniature experiments’ in a single day.

“And ‘omics’ tools provide a three-part fundamental ‘cataloguing’ of the capabilities of a particular biocatalyst organism. Genomics allows one to identify 

all of the genes that are expressed within an organism. Proteomics identifies 

all of the enzymes or other proteins that an organism produces and metabolomics identifies all of the small molecule metabolites that an organism produces during growth. With these research tools, our researchers now have 

dramatically enhanced capabilities from just a few years ago for developing 

new strains to carry out desired biomass conversions.”

NREL has been acquiring some of the new equipment over the last couple 

years and now has it all set up in a superb facility in two new laboratories in 

the Field Test Laboratory Building. The new Biology Systems Laboratory is a 

great complement to the recently opened Biomass Surface Characterization 

Laboratory.

“Together they arm NREL biomass conversion research efforts with the best 

tools available, and we look forward to using them to making key advances 

in the biofuels area,” says Darzins. n

Al Darzins, manager of NREL’s Applied Sciences Group, 

loads samples into an automated, high-throughput, liquid 

handling workstation in the Systems Biology Laboratory. 

The instrument can be programmed to simultaneously 

perform thousands of scientific experiments.
	 24	 2006 NRELResearchReview PIX03987

microalgae that produce high levels of 

lipids (oils) for processing into biodiesel. 

NREL developed an extensive microalgae culture collection as well as a toolkit 

for the genetic engineering of these 

organisms. NREL Analyst John Sheehan, 

who managed the last few years of the 

microalgae program, cited economic 

factors for its being set aside.

“In addition to having to compete with 

57-cent-per-gallon diesel at the time, 

one of the main reasons for dropping 

the microalgae program was realizing 

that even using simple outdoor ponds, 

the capital cost of facilities for growing 

the microalgae would always keep the 

technology relatively expensive,” says 

Sheehan. “Today, however—in addition 

to dramatically higher petroleum diesel 

cost—low plastic container cost makes 

the possibility of growing the algae 

in closed systems such as transparent 

tubular reactors a very realistic possibility and is making the technology much 

more attractive again.”

NREL Scientist Eric Jarvis, a genetic engineering specialist, is especially excited 

about the possibility of restarting microalgae research because of new capabilities developed since the mid-1990s.

“The metabolic engineering we did to 

try to make microalgae produce more 

lipids was cutting edge at the time,” says 

Jarvis, “but the whole field of genetic 

engineering has advanced so dramatically since then that we will now have 

far greater ability to improve the organisms’ performance.” (see “New Lab” sidebar on page 23).

Another exciting reason for reestablishing microalgae research is the possibility 

of developing a new end product. 

Rather than converting the microalgal 

oil to biodiesel, it is possible to chemically convert it to jet fuel. The same 

hydrotreating process that could make 

pyrolysis oil a good oil refinery feedstock could also convert microalgal oil 

into kerosene, the basic component of 

jet fuel.

Jet fuel now accounts for about 8% of 

our petroleum use and no renewable 

alternative has been developed to this 

point. Ethanol is not dense enough, having only about half the energy per volume of jet fuel. Biodiesel has about 80% 

Next-Generation Fuels—What’s Old Is New Again

NREL researchers were able to draw on the laboratory’s extensive culture 

collection to develop strains of algae with high levels of lipids.

the energy density of kerosene, but can 

solidify at the low temperatures of high 

altitude flight.

Industry is very interested in this process because it could utilize existing 

hydrotreaters in the nation’s oil refineries. A likely R&D participant is the U.S. 

Department of Defense, which is seeking a non-petroleum replacement for 

military jet fuel.

Darzins likes to characterize all of these 

research efforts as developing “nextgeneration fuels.”

“They will probably never be as large 

as our ethanol or hydrogen research 

programs, but they could lay groundwork for key contributions to meeting 

our transportation energy needs,” says 

Darzins. “Knowing that NREL has a running head start on them because of our 

past research says a lot about the value 

of our broad and continuing commitment to meeting transportation and 

other energy needs with renewable 

energy.” n
	 Forbackgroundinformation & technicaldetails: www.nrel.gov/research_review/	 25 PIX14691 PIX11977

As the preceding pages illustrate, NREL’s scientists 

and engineers are engaged in innovative research 

and development that is changing the way energy is created and used. However, research and 

development is only part of what we do. To effectively pursue our mission and take on the nation’s 

energy challenges, it is critical that NREL’s technological advances and solutions reach the marketplace in a timely manner. Through our numerous 

collaborations with industry, we ensure that our 

research and development is properly focused 

and market relevant. Our alliances with companies, universities, and other federal laboratories 

also increase the knowledge base and innovative capacity of NREL’s technical staff, allowing us 

to better capitalize on the national investment in 

NREL’s important work.

Each year NREL’s world-class staff works with 

industrial, academic, and government organizations on literally hundreds of projects. In addition to our collaborative projects, we test and validate technologies using our expertise, facilities, 

and equipment; prepare focused informational 

reports using our knowledge of state-of-the-art, 

clean, energy-related technologies; share NRELdeveloped software tools with the broader community; and license our patented technologies to 

entrepreneurial and established companies.

Any of these technology transfer mechanisms can 

lead to the creation of new enterprise opportunities for business growth and development, and 

accelerate the transition of NREL-developed technologies to the marketplace. “Accelerate” is a key 

word for us—our nation’s energy challenges are 

immense and immediate, and we must rapidly 

move technologies out to our industrial partners 

in order to increase our nation’s energy security, 

reduce the environmental impacts of energy use, 

and bolster U.S. competitiveness and productivity. 

The examples presented in this issue of the 

Research Review are but a snapshot of our research 

and development projects that will lead to technology transfer activities. Technology is continually being transferred between NREL staff and the 

dozens of outside parties with which we interact. And it is not just a one-way flow, but a twoway exchange of ideas, problems, and solutions 

through individual and collective innovation. That is how we work: always with the goal of moving new 

concepts and technologies from the laboratory to applications that benefit society.

For more details on NREL’s technology deployment and commercialization activities, visit our Technology 

Transfer Web site at www.nrel.gov/technologytransfer/ and pick up a copy of our inaugural Technology 

Transfer Report, due out in late summer 2007. n

CapitalizingontheNation’sInvestment

NREL worked with Northern Power Systems to develop a 

1.5-megawatt direct-drive generator for wind turbines, 

shown here during testing at NREL’s National Wind 

Technology Center.

Every other year, NREL helps to sponsor and manage the 

Solar Decathlon on the National Mall. The event encourages 

university students to incorporate the latest technologies 

into small solar-powered, energy-efficient homes.
National Renewable Energy Laboratory

1617 Cole Boulevard, Golden, Colorado 80401-3393

303-275-3000 • www.nrel.gov

Operated for the U.S. Department of Energy

Office of Energy Efficiency and Renewable Energy

by Midwest Research Institute • Battelle

Contract No. DE-AC36-99-GO10337

NREL/MP-840-40764 • July 2007

Printed with renewable-source ink on paper containing at least 

50% wastepaper, including 10% post consumer waste. 

Notice

This report was prepared as an account of work sponsored by an agency of the 

United States government. Neither the United States government nor any agency 

thereof, nor any of their employees, makes any warranty, express or implied, or 

assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that 

its use would not infringe privately owned rights. Reference herein to any specific 

commercial product, process, or service by trade name, trademark, manufacturer, or 

otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views 

and opinions of authors expressed herein do not necessarily state or reflect those of 

the United States government or any agency thereof.