Director’s Discretionary 

Research and Development 

Program 

Annual Report 

Fiscal Year 2005 

National Renewable Energy Laboratory 

1617 Cole Boulevard 

Golden, Colorado 80401-3393 

NREL is a U.S. Department of Energy Laboratory 

Operated by the Midwest Research Institute • Battelle 

 NREL/MP-700-38759 

 December 2005 
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. 

 Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste 
iii

Table of Contents 

Introduction ........................................................................................................1 

Program Overview ............................................................................................2 

Program Successes ..........................................................................................4 

Program Investments and Value – Project Summaries .................................5 

Advanced Analytic Methodologies and Systems ................................................................................................5 

Advanced Materials for Renewable Energy and Energy Efficiency Technologies ...........................................6 

Advanced Measurement and Characterization Techniques..............................................................................16 

Bioenergy, Biotechnology, Chemistry ..............................................................................................................17 

Computational Sciences ......................................................................................................................................25 

Electric and Hydrogen Technologies Systems ..................................................................................................26 

Appendix A. Acronyms and Symbols ............................................................29 
iv
Introduction 

Technical innovation is central to the National Renewable Energy Laboratory’s mission. 

Innovative discretionary research maintains the scientific and technical vitality of the Laboratory, 

enhances the Laboratory’s ability to address future DOE missions, and serves as a proving 

ground for new and potentially high-value mission enhancing activities. Discretionary research 

can provide technology pathways for the Office of Energy Efficiency and Renewable Energy 

(EERE) to attain the Department of Energy’s long-term goals, and can accelerate progress on 

existing technology pathways. The Director’s Discretionary Research and Development 

(DDRD) Program enables researchers to explore novel opportunities within the Laboratory’s 

assigned mission areas, pursue more speculative ideas, and thereby move the science from the 

realm of imagination to creation and toward application. Research supported by the DDRD 

Program augments DOE’s research and development capabilities, enhances the reputation of 

the Laboratory, encourages new partnerships that can advance EERE and DOE missions, and 

can result in technology breakthroughs. 

This report highlights NREL's investment in innovation and the value of that investment to the 

Laboratory and to DOE and EERE. 

DDRD is Innovation

Idea Incubation -

New Concept

Knowledge Creation

Knowledge Exchange

Knowledge Adoption

Technical risk is a significant barrier to bringing untested ideas into an applied research 

portfolio. DDRD reduces risk at the incubation stage.

DDRD is Innovation

Idea Incubation -

New Concept

Knowledge Creation

Knowledge Exchange

Knowledge Adoption

Technical risk is a significant barrier to bringing untested ideas into an applied research 

portfolio. DDRD reduces risk at the incubation stage.

 

Figure 1. DDRD funds innovative projects within NREL's mission areas. 

 It also provides the tools necessary to move resulting concepts to applications. 

 NREL’s 23 active projects cover six technology areas.

1
Program Overview 

The DDRD Program funded 23 projects in fiscal year 2005. The duration of DDRD projects 

ranges from 2 to 3 years. The projects fall in six technical disciplines, which crosscut the 

Laboratory’s mission areas: 

• Advanced Analytic Methodologies and Systems 

• Advanced Measurement and Characterization Techniques 

• Advanced Materials 

• Biotechnology, Chemistry 

• Computational Sciences. 

2

Technical Disciplines of FY05 DDRD Funds

Advanced Analytic 

Methodologie and s 

Syste s Computational Sciences m

9% Biotechnology, 

4%

Advanced Measuremen Chemistry t 

and Characteriz tion 39% a

Techniques

9%

Advanced Materials

39%

Figure 2. NREL’s 23 active projects cover six technical disciplines. 

Projects within the aforementioned cross-cutting technical disciplines have the potential to 

provide new research pathways for DOE programs in the following energy application areas: 

• Biomass conversion, bioenergy

• Distributed energy systems and storage

• Hydrogen generation

• Buildings, national security

• Energy system analysis

• Photovoltaics, solid state lighting. 
3

Potential Application Areas of DDRD Projects

Distributed

Biomass

energy systems 

conversion, and storage

bioenergy 11%

16%

Hydrogen 

generation

15%

Buildings, 

national security

Photovoltaics, 1%

solid state 

Energy systems lighting

analysis 48%

9%

Figure 3. DDRD projects are yielding many potential renewable energy and 

energy efficiency innovations. DDRD efforts are strongly aligned with efforts in 

photovoltaics, solid state lighting, biomass conversion, and hydrogen. 

Twenty eight proposals were submitted in response to the call for proposals in April 2004, of 

which 10 new projects were selected for funding in FY05. In all, 23 DDRD projects were 

executed in FY05. 

 New and Ongoing Projects in FY05

New Starts in FY05

37%

Multi-Year Projects 

Carried Over from FY04 

63%

Figure 4. Funding in the amount of $1.4 million was 

 available for new projects in FY05. 
4

FY05 Program Successes 

The DDRD program continued to yield innovations and new capabilities in FY05 that strengthen 

the future value NREL can bring to DOE programs. The following outcomes are illustrative of 

the value gained from DDRD research in FY05. These examples and additional ones are 

described in more detail in the Program Investments and Value section of this report. 

• NREL DDRD research confirmed a very novel alternative approach for producing 

hydrogen from biomass that combines biomass steam pretreatment and anaerobic 

digestion. Though yields are lower than for thermochemical methods, this strategy can 

be applied to both dry and wet biomass. As a result of this research the DOE Hydrogen, 

Fuel Cells, and Infrastructure Program decided to further study anaerobic fermentation 

of lignocellulosic biomass as a potential low-cost technology for producing hydrogen 

from waste biomass. 

• NREL DDRD research developed new optical microscopy tools to study 

photoluminescence quenching in thin films of conjugated polymers. The results enable 

an understanding of the quenching process efficiency and the range over which it can 

operate, and is being applied to support both photovoltaic and bioenergy investigations. 

• NREL DDRD research developed new capabilities in fabricating and characterizing 

organic light-emitting diodes and synthesizing organic semiconductors such as 

dendrimers, oligimers, and polymers. These capabilities support the goal of producing 

low cost, high efficiency solid state indoor lighting from organic white light emitting 

diodes. 
5

Program Investments and Value

Advanced Analytic Methodologies and Systems

Expert System for the Modeling of Renewable Energy Use

Principal investigator: Walter Short

Award: $142,000

Period of Performance: May 2003 to September 2005

Status: Completed

Goal

This effort will ultimately result in improvements in existing energy market models and help 

inform policy makers who rely on these models and analysis for insight. Most existing energy 

market forecasting models were built with a focus on conventional energy technologies. As 

such, they do a poor job of estimating the potential for most renewable energy technologies to 

address the nation’s energy and environmental goals. 

The modeling projects underway at NREL not only provide better estimates of wind and 

photovoltaics (PV) potential, they also translate the findings in a way that can be used by 

existing macro models, which cannot delve into the same level of detail with respect to 

renewables. The scientific/technical problem that was resolved is how to best transfer NREL's 

reduced-form supply curves to macro models.

Investment Outcome

For the first time, NREL specific market issues with respect to wind, concentrating solar power 

(CSP) and hydrogen can be modeled. As such, DOE can now examine different scenarios, and 

authoritatively estimate the impact of these technologies in the marketplace. 

The project team accomplished this by developing reduced-form versions of NREL’s wind model 

that could be used in other models to represent the extra-generational costs associated with 

wind including the additional costs of transmission access and the cost of additional capacity to 

cover the intermittency of wind, etc. Curves of the above-busbar cost ($/kW of additional wind) 

versus the total national wind capacity were generated after reviewing other models and 

reduced-form methodologies, and experimenting with various calculation methods to determine 

the additional cost. 

Because of the complexity of NREL’s wind deployment system (WinDS) model, it is not 

computationally practical to incorporate it into other models. Thus, a reduced-form 

representation derivable from the WinDS model is required to capture the sensitivity of the 

driving variables without the full representation of the physical realities. Other model developers 

can now use NREL graphs in their models to more accurately represent the costs of wind 

transmission and wind intermittency and calculate their impact on market penetration.

NREL has implemented this reduced-form approach in the single-region Stochastic Energy 

Development Systems (SEDS) model which uses the WinDS-derived supply curve to capture 

the wind transmission and intermittency costs and constraints. The implementation of these 

wind supply curves in other models will improved the quality of EIA’s Annual Energy Outlook for 

wind through its NEMS model. Currently several other models – IPM, NEMS-GPRA 

(Government Performance Results Act), and Haiku – use the EIA's cost correction factors that 
6

severely limit wind and have no analytic basis. The work provides superior support tools for 

DOE to Model renewable energy markets. 

Value of the Outcome

Local, national, and international decision makers depend heavily on the energy projections 

provided by various macroeconomic models including the U.S. EIA's NEMS model, the 

MARKAL model, and others. However, up to now it was difficult for these models to provide 

accurate information on the potential of renewable energy because of historical focus on 

conventional power sources and very limited special disaggregation; for example, NEMS 

includes only 13 regions within the United States.

For the first time, DOE can use quantitative methods to accurately model important market 

issues related to renewable energy, including transmission access and intermittency impacts, 

instead of using crude approximations. The use of reduced-form output supply curves 

combined with dissemination of other WinDS results will greatly improve DOE’s renewable 

energy forecasts and analysis from all energy models and enhance EERE’s ability to model the 

outcomes of renewable program efforts.

Advanced Materials for Renewable Energy and 

Energy Efficiency Technologies

Hot-Wire Chemical Vapor Deposition of Metal Oxide Nanorods 

Principal Investigators: Anne Dillon and Harv Mahan 

Award: $300,000 

Period of Performance: October 2004 to September 2006 

Status: In Progress 

Goal 

To investigate production of metal oxide nanorods and nanoparticles for use in electrochromic 

windows and batteries. 

Investment Outcome 

The team's preliminary tests are very promising. There is a crystalline molybdenum trioxide 

powder containing nanoparticles/nanorods at high density that, when fashioned into a film, is 

ideal for incorporation into a lithium-ion battery. These films have been tested as anodes in 

lithium-ion batteries, and the reversible capacity for several films vastly exceeds that of the 

currently employed technology (graphite). 

The team is investigating other applications for the high surface area tungsten trioxide 

nanoparticle materials. GVD Corporation in Cambridge, Massachusetts has expressed interest 

in testing this material in a hydrogen sensor device. An informal collaboration agreement is in 

process. 

High surface area crystalline metal oxides may have applications beyond those that are 

currently under investigation. 

Value of the Outcome 

This work provides a potential new technical approach for DOE’s research in electrochromic 

windows and energy storage. Tungsten-oxide nanoparticles significantly improve the state-ofthe-art electrochromic (EC) technologies as they are significantly more stable in an acid 
7

electrolyte solution. This could allow for EC technologies to be used in display applications. 

Preliminary results suggest that molybdenum-oxide nanostructures could profoundly advance 

the negative electrodes employed in Li+ batteries. 

Knowledge Transfer 

• "Deposition of Small, Highly Crystalline WOx Nanoparticles and Nanotubes by 

Evaporation of a W filament in an Oxygen Atmosphere," by A.H. Mahan, P.A. Parilla, 

K.M. Jones, and A.C. Dillon, Chem. Phys. Lett. 413 (2005) 88-94. 

• "Crystalline WO3 Nanoparticles Electrochromic Breakthrough," by S.H. Lee, R. 

Deshpande, P. A. Parilla, K. M. Jones, B. To, A. H. Mahan, and A. C. Dillon, Advanced 

Materials (under review). 

• A follow-up paper to this rapid communication is in preparation. 

• "Novel Nanostructured Materials for a Variety of Applications," invited talk presented at 

the August 2005 SPIE meeting in San Diego. 

• "Metal-oxide Nanostructures for Electrochromic and Battery Applications," invited talk 

presented at the October 2005 National Institute of Standards and Technology (NIST) 

Nanoscience Workshop in Boulder. 

• Two abstracts have been accepted for oral presentations at the fall 2005 Materials 

Research Society (MRS) Conference. 

o "Hot-wire Chemical Vapor Deposition of Crystalline Tungsten Oxide 

Nanoparticles,” presented by A. H. Mahan. 

o "Electrochromic WO3 Nanoparticles Consisting of Nanorods and 

Nanospheroids," presented by R. Deshpande. 

• This team has been invited to submit a white paper on these early results to the Naval 

Research Laboratory (NRL) in Arlington, Virginia. 

Next Steps 

The principal investigators have started exploring metal-oxide structures for battery applications. 

The work has the potential to significantly improve lithium ion battery technologies, which could 

lead to the development of a more efficient battery for the next generation hybrid electric 

vehicles, supporting the goals of DOE’s Freedom Car Program.

Improved Thermoelectric Materials Based on Quantum Dot Superlattices 

Principal Investigator: Mark Hanna 

Award: $200,000 

Period of Performance: May 2003 to April 2005 

Status: Completed 

Goal 

To investigate a new concept for improving the thermoelectric figure of merit of III-V 

semiconductor thin films (with potential applications in electronic and optoelectronic devices), 

namely the use of quantum dot superlattices to enhance the Seebeck coefficient and reduce the 

cross-plane thermal conductivity. 

Investment Outcome 

Mark Hanna's team developed a new crystal growth capability to produce high-quality quantum 

dot superlattices (QDSL). This new growth capability gives NREL the ability to produce novel 

structures and devices based on QDSL for both fundamental and device studies. 
8

The team implemented an experimental setup for measuring the thermal conductivity of thin 

films based upon AC-modulated sample heating and temperature detection, called the 3-omega 

technique. With this setup, NREL now has a new capability to measure the thermal conductivity 

of new materials used in thermoelectric and photovoltaic applications. 

The 3-omega setup was then used to measure the cross-plane thermal conductivity of a number 

of QDSLs with different structures. The team found that the cross-plane thermal conductivity of 

indium gallium arsenide/gallium arsenide (InGaAs/GaAs) QDSLs was reduced by a factor of two 

to eight below that of GaAs depending upon the superlattice structure and doping level. The 

large reduction in the thermal conductivity by a factor of eight shows that QDSLs are an 

effective means to reduce the lattice thermal conductivity of a material – thereby achieving one 

of the main goals of the project. 

Value of the Outcome 

This work provides a potential new approach for developing QDSL devices which could provide 

innovative technologies to meet DOE’s PV program goals. 

Solid-State Nano-Composite Materials for Supercapacitor Applications 

Principal Investigator: Se-Hee Lee 

Award: $240,000 

Period of Performance: March 2003 to February 2005 

Status: Completed

Goal 

To develop a new class of solid-state supercapacitor based on novel nano-composites of 

polycrystalline particles embedded within an amorphous electrolyte matrix. 

Investment Outcome 

The team successfully synthesized nano-structured nickel oxide thin films employing a method 

called reactive sputtering, and demonstrated that the defective nature of nickel oxide could be 

utilized to improve the specific capacitance for supercapacitor application. Although the specific 

capacitance of the nickel oxide supercapacitor was affected by the fabrication process, the 

relationship between specific capacitance and nonstoichiometry is not understood. Therefore, 

the team is proposing further study of the mechanism underlying this relationship. 

The electrochemical performance of single wall carbon nanotube (SWNT)/Nafion composite 

electrodes have been examined in sulfuric acid solutions. The electrochemical capacitance of 

the composite electrode increases significantly after an oxidation-reduction cycle. The team 

has shown that electrochemical oxidation of SWNT/Nafion composite electrodes, at high 

potentials in a strong acidic media, provides a new method of chemical modification of the 

SWNTs. The electrochemical oxidation and reduction treatment of the SWNT/Nafion composite 

is potentially useful for modifying the SWNT sidewalls, which results in an enhancement of the 

electrochemical capacitance. 

The team has successfully demonstrated electrochemical capacitive behavior of the Nickel 

oxide/Tantalum oxide (NiO/Ta2O5) nano-composite films in an aqueous solution for the first 

time. These nano-composite materials promise great potential for fabricating complete solidstate supercapacitors. This unique nano-composite material construction exhibits a substantial 

electrochromic (EC) optical modulation and may lead to the establishment of a new class of EC 

materials based on a supercapacitance effect. 
9

The team has performed in-situ Raman spectroscopy measurements on amorphous hydrous 

ruthenium oxide thin films during the charging/discharging cycles in an effort to elucidate the 

physical and chemical changes that accompany the electrochemical cycles. Amorphous 

hydrous ruthenium oxides (RuO2·xH2O) have attracted much interest with respect to the 

possibility of using this material in electrochemical supercapacitors. The cause of the physical 

and chemical changes that occur when hydrogen is inserted or extracted from this material 

during the charging/discharging cycles is not clear. However, based on the Raman 

spectroscopic studies of these materials, the major effect upon intercalation of hydrogen is 

reduction of Ru4+ ions to Ru3+, and not the creation of new chemical bonds. 

Value of the Outcome 

The electrochemical capacitor (ECC) is an attractive device for high power density applications. 

When combined with secondary batteries, electrochemical capacitors provide additional 

versatility and efficiency in the management of portable power sources. Recent 

accomplishments pertaining to both inorganic nano-composite material (nickel oxide/tantalum 

oxide) and organic-inorganic nano-composite material (SWNT/Nafion) directly impact two 

important areas of energy-related research: energy storage, and nano-science/nanotechnology. Based on the team's recent development of these nano-composite supercapacitor 

materials, the possibility exists to fabricate complete solid-state supercapacitors with properties 

that rival liquid/gel electrolyte-type devices. Technical innovation in energy storage can facilitate 

the deployment of the variety of renewable power sources being pursued through DOE 

research. 

Knowledge Transfer 

• "Electrochemical transformation of single-walled carbon nanotube/Nafion composite," by P. 

Liu, S.-H. Lee, Y. Yan, T. Gennett, B. J. Landi, A. C. Dillon, and M. J. Heben, 

Electrochemical and Solid-State Letters, 7(11) A421 (2004). 

• "Effect of non-stoichiometry of nickel oxides on their supercapacitor behavior," by S.-H. Lee, 

C. E. Tracy, and J. R. Pitts, Electrochemical and Solid-State Letters, 7(10) A299 (2004). 

• "Effect of O2 flow concentration during reactive sputtering of Ni oxide thin films on their 

electrochemical and electrochromic properties in KCl and KOH electrolytes,” by Y. Abe, S.-

H. Lee, E. O. Zayim, C. E. Tracy, J. R. Pitts, and S. K. Deb, J. Electrochem. Soc., 

(submitted).

• "Electrochromic properties of sputtered Ni oxide thin films in neutral KCl electrolytes," by Y. 

Abe, S.-H. Lee, C. E. Tracy, and J. R. Pitts, Electrochemical and Solid-State Letters, (in 

press). 

• "In-situ Raman spectroscopy of RuO2·xH2O," by H. C. Jo, K. M. Kim, H. Cheong, S.-H. Lee, 

and S. K. Deb, Electrochemical and Solid-State Letters, 8(4) E39 (2005). 

• "Nanophase nickel oxide electrodes with ruthenium oxide additions for supercapacitor 

applications," by R. Smith, S.-H. Lee, C. E. Tracy, and R. Pitts, J. Electrochem. Soc., 

(Submitted). 

• "Solid-state nano-composite electrochromic pseudocapacitors," by S.-H. Lee, C. E. Tracy, Y. 

Yan, J. R. Pitts, and S. K. Deb, Electrochemical and Solid-State Letters, 8(4) A188 (2005). 

CgMgTe Thin Films for Light Emitting Diodes 

Principal Investigator: Kannan Ramanathan 

Award: $300,000 

Period of Performance: October 2004 to September 2006 

Status: In Progress 
10

Goal 

To fabricate blue and blue-green light emitting diodes (LED) out of a novel material, Cadmium 

Magnesium Telluride (CdMgTe). 

Investment Outcome 

Kannan Ramanathan and his team fabricated the first polycrystalline thin films made of 

CdMgTe—overcoming equipment and staffing problems. They set up a new fabrication facility 

that uses effusion cells. The fabricated films are a fine example of multi-component alloy 

preparation using combinatorial synthesis. With two depositions, they can cover the 

composition range of 1.4 eV to 2.2 eV. They have established the basic properties of the alloys 

such as energy gap vs. composition and they are sending a paper to Applied Physics Letters. 

Value of the Outcome 

Significant progress has been made to achieve the objective of LED device fabrication. This 

work can potentially provide a new avenue for DOE’s research in solid state lighting. 

Next Steps 

Kannan’s team plans to fabricate the LED’s in FY06. A side benefit is that this same material 

can be used to develop a wide bandgap solar cell out of the 1.7 eV material.

OWLEDs: Next Generation Indoor Lighting Using Organic White Light Emitting 

Diodes 

Principal Investigator: Sean Shaheen 

Award: $500,000 

Period of Performance: April 2003 to March 2005 

Status: Completed 

Goals 

• To perform fundamental research on organic semiconductors and organic/inorganic 

hybrid nanostructured materials with the end goal application of low cost, high efficiency 

solid state indoor lighting from organic white light emitting diodes (OWLEDs). 

• To develop a core competency at NREL in the area of organic semiconductors and 

nanostructured materials, including the development of personnel and staffing at NREL, 

as well as the construction of laboratory tools necessary to carry out research in this 

area at a high level. 

Investment Outcome 

NREL now has a new capability: to fabricate and characterize organic light emitting diodes 

(OLEDs). This capability did not exist before this project. The organic semiconductor synthesis, 

purification, and characterization laboratory facility is suitable for the fabrication of many types 

of organic semiconductor devices, such as dendrimers, oligomers, and polymers. 

These new capabilities allow NREL researchers to develop novel materials, better understand 

structure-property relations, and to optimize device performance. The team collaborated with 

NREL's Computational Sciences team to model the structure-property relations of new materials 

via computational chemistry modeling, which aides the design of novel organic semiconductors. 

Value of the Outcome 

NREL’s newly developed high-efficiency organic semiconductor device laboratory, which is on 

par with leading labs in the world, can help advance DOE’s goals in solid state lighting. The 

knowledge base at NREL has been greatly increased in the field of organic semiconductors, 
including synthesis and characterization of new materials and fabrication and characterization of 

new devices. The results will be published in the Journal of Materials Chemistry. 

Low Band-Gap Materials for Organic Third Generation Photovoltaics 

Principal Investigator: Sean Shaheen 

Award: $450,000 

Period of Performance: December 2004 to September 2006 

Status: In Progress 

Goals 

• To develop a competency in the fabrication of organic semiconductor based photovoltaic 

devices, including facilities and personnel to establish NREL as a world-class Laboratory 

in the field. 

• To develop low band gap materials that have optimized transport properties for use in 

organic photovoltaics; and improve the scientific understanding of the structure-property 

relation of these materials. 

• To improve the understanding of the physics of the operation of these devices and 

develop models to guide their advancement. 

Investment Outcome 

Sean Shaheen's team synthesized and characterized a family of dendrimeric organic 

semiconductors with a variety of molecular structures based on thiophenes. This first set of 

materials is helpful in understanding the structure-property relations of dendrimers. Fabrication 

and characterization of devices from initial materials demonstrate the efficient charge transfer 

and charge transport in these new dendrimer materials. Clear trends in device efficiencies can 

be seen in relation to the molecular structures of the dendrimers. Results of this work have 

been submitted for publication. 

The team has started synthesizing the next iteration on dendrimers that possess reduced 

optical band gaps. The first family of dendrimers had optical band gaps ranging from 2.5 eV to 

2.7 eV in solution, and 2.3 eV to 2.6 eV in film. NREL’s new dendrimer has a band gap of about 

2.0 eV in solution and 1.8 eV in film. This data is shown in the attached figures. 

a)

S

S

S

S

S

S

S

S

S

S

S

S

S

S

S

 b) 

S

S

S S

S

S

S

S

S

S

N

N

N

S S S

S

S

Figure 5 a, b. Computational modeling. With the help of the 

Computational Sciences Center, the team is running computational chemistry calculations to 

further understand the structure-property relations of the dendrimers being synthesized. 

Computer modeling will be a powerful resource in the development of future materials.

11
Figure 6. This figure is a three-dimensional 

 structure of the dendrimer depicted in figure 5a.

The team performed Preliminary time-resolved microwave conductivity measurements on 

dendrimers. Preliminary results show very long-lived charge carriers in some of the dendrimers. 

This agrees with the premise that these materials are very pure and have few defects that can 

act as charge traps. 

NREL, in partnership with the University of Minnesota, was selected for a competitive research 

award under the Xcel Energy renewable development fund. This project will enable exploring 

various avenues of improving organic photovoltaic devices. 

Two carrier mobility measurement setups are comlete: Time-of-Flight (TOF) and Current 

Extraction by Linearly Increasing Voltage (CELIV). Having two techniques available provided a 

more robust and substantiated measurement of a given material’s mobility. 

After characterizing the first family of dendrimers in terms of optical properties and device 

performance, the first module of the next iteration has been synthesized. This module has a 

significantly reduced optical band gap compared to the first family. The process of 

characterizing the transport and device properties of this material is underway. 

Value of the Outcome 

Overall, this program is helping NREL develop novel organic semiconductors for photovoltaic 

and other applications in support of DOE’s Solar Program goals. 

Knowledge Transfer 

• "Bulk heterojunction organic photovoltaic devices based on phenyl-cored thiophene 

dendrimers," by N. Kopidakis, W. Mitchell, D. Ginley, G. Rumbles, S. Shaheen, Thin 

Solid Films (submitted).

• "The Synthesis and Properties of Solution Processable Phenyl Cored Thiophene 

Dendrimers," by W. Mitchell, N. Kopidakis, G. Rumbles, D. Ginley and S. Shaheen, 

Journal of Materials Chemistry, 15(42) 418 (2005). 

• Collaborations with Prof. C. Daniel Frisbie, University of Minnesota; and with Delft 

University resulted in shared insights on organic photovoltaics and basic materials 

characterizations on new dendrimer materials. 

12
13

Next Steps 

The new dendrimer has a reduced band gap compared to the first family of materials. The next 

step is to fully characterize this material in terms of its carrier mobility and device performance. 

This molecule utilized just one technique available to the team for reducing the band gap. The 

team also has several other approaches available, which they will begin to explore as well. 

Single Molecule Fluorescence Detection and Imaging 

Principal Investigator: Steve Smith 

Award: $240,600 

Period of Performance: March 2003 to April 2005 

Status: Completed 

Goal 

To develop an optical microscopic tool for the detection of single, isolated molecules and for the 

development of a near-field optical microscope with a spatial resolution below the diffraction 

limit of optical radiation. The tool would be applied to the study of photoluminescence quenching 

in thin films of conjugated polymers, where the process could be attributed to photoinduced 

electron transfer to an inserted dopant species such as C60. This polymer/C60 combination can 

be found in the bulk heterojunction excitonic solar cell, and the results are, therefore, pertinent 

to the understanding of the efficiency of the quenching process and, most importantly, the range 

over which it can operate. 

Investment Outcome 

The team developed a microscope with sub-wavelength and single-species resolution. This is a 

new tool for NREL. Isolated dye molecules and colloidal quantum dots have been detected and 

fluorescence correlation spectroscopy developed. This is critical to understanding isolated 

species in their environment and how they are responding. 

The team also visualized and modeled novel systems: single-molecule Raman detection of dye 

molecules adjacent to metal nanoparticles; and detection of colloidal quantum dots (QD) bound 

to a genetically modified protein. These results demonstrate the capability of the techniques, 

provide new data that has been published, and serve as a foundation on which new proposals 

can be developed. 

Value of the Outcome 

New spectroscopic tools, new expertise, new collaborations, and new proposals emerging from 

this work are supporting both photovoltaic and bioenergy investigations. These newly 

developed capabilities catalyzed a new project in bioenergy to look at QD-labeled proteins 

moving on a cellulose surface. The cross-fertilization resulting from this project has the 

potential to advance DOE goals in both the PV and Biomass Programs. 

Electronic Communication in Assemblies of Semiconductor Nanoparticles 

Principal Investigator: Jao van de Lagemaat 

Award: $300,000 

Period of Performance: May 2003 to September 2005 

Status: Completed 

Goal 

To provide a framework for connecting electronic communication in a macroscopic film of 

interconnected nanoparticles with the energetic structure of isolated quantized nanoparticles. 
14

Investment Outcome 

NREL is now well positioned in the field of conversion technology because of its ability to 

visualize, model, and study the energy structure of nanomatter. Jao van de Lagemaat’s team 

was able to precisely visualize individual quantum dots and to determine their charging 

spectrum. Quantum dots are a non-traditional type of semiconductor with potential applications 

as an enabling material across many industries. Quantum dots enable semiconductors with 

tunable bandgaps, allowing for unique optical and electronic properties. Knowledge of the 

charging spectrum of individual dots is of paramount importance to understanding charge 

conduction in large arrays of dots–a system that can potentially create third generation high 

efficiency, low cost photovoltaics. 

The team developed a computer model of charge transport (i.e. electronic communication) 

using tunneling spectroscopy to calculate the charging spectrum of individual quantum dots or 

direct measurement results. Providing a framework to connect electronic communication in a 

macroscopic film of interconnected nanoparticles with the energetic structure of isolated 

quantized nanoparticles was the overriding goal of this project. The computer model 

successfully accomplishes this goal and illustrates the success of the DDRD project. It also 

shows that NREL is well positioned to model and predict the properties of large-scale 

assemblies of nanoscaled matter. This is of major importance in guiding the design of solar 

energy conversion and storage technologies based on such systems. The computer model was 

also adapted to describe another nanoparticle array system, the titanium dioxide (TiO2) 

nanoparticle layer employed in dye-sensitized solar cells to show that a similar effect owing to 

energetic disorder, is active there even though the particles in this case are not quantized. In 

cooperation with Art Frank's group, the team showed that the predictions of the model were 

correct. The results were submitted to Physical Review B during FY 05. 

Value of the Outcome 

The fundamental knowledge obtained in this project is applicable to all systems that have a 

degree of energetic disorder and/or long-range interactions. This includes diverse systems 

such as organic solar cells, amorphous silicon, the dye-sensitized solar cell, thin-film systems, 

and much more. 

Knowledge Transfer 

• "Einstein relation for electron diffusion on arrays of weakly coupled quantum dots," by 

J. van de Lagemaat, Phys. Rev. B (Submitted 29Aug. 2005).

• Peer-review publications and presentations of fundamental results at conferences are 

expected to lead to new collaborations and contribute to NREL's strong image as a 

steward of good science. It has already led to one collaboration with the group of Prof. 

J. Bisquert at the University Jaume I in Castello Spain. He has spent time at NREL 

discussing the science of these systems and is sending one of his collaborators over for 

a few months in FY06. 

• One other collaboration being discussed, is with Prof. D. Vanmaekelbergh of Utrecht 

University, The Netherlands; he is a pioneer in this field. 

Fundamental Properties and Applications of Novel Crystalline Inorganic-Organic 

Hybrid Semiconductor 

Principal Investigator: Yong Zhang/Brian Fluegel 

Award: $450,000 

Period of Performance: October 2004 to September 2007 

Status: In Progress 
Goal 

To obtain and understand the basic electronic and optical properties of single layer structures. 

Investment Outcome 

In the first year of this project, the team made major progress in understanding the fundamental 

properties of the hybrid materials. They demonstrated the vertical conductivity of hybrid thinfilms (double-layer structures) deposited on indium tin oxide (ITO) substrates using flexible top 

gold (Au) contacts; and observed that the conductivity exhibits rectification behavior. A number 

of interesting properties have been revealed and a preliminary device operation has been 

demonstrated. NREL is now better prepared to synthesize hybrid materials and test realistic 

devices either for photovoltaics (PV) or solid state light (SSL) applications. 

Collaborations resulting from this project have significantly expanded NREL's capability in 

researching novel materials. 

Value of the Outcome 

Hybrid inorganic-organic semiconductor materials are new materials that exhibit unique optical 

and electrical properties that constitute the most recent development in materials science. The 

acquisition of expertise in these materials can open up new and exciting materials and device 

research opportunities for photovoltaic applications. Collaboration with a university provides 

added value in graduate level education for future scientific manpower for the nation. 

Figure 7. Crystal structure of an organic-inorganic hybrid semiconductor, β-ZnTe(en)0.5, determined 

by X-ray diffraction: multiple ZnTe layers (green and red atoms) interconnected by ethylenediamine 

molecules (white C and blue N atoms, hydrogen atoms omitted) at Zn atoms.

Next Steps 

• Carefully study the thermal and vibrational properties of the hybrid materials. 

• Perform electronic and band structure calculations for the double-layer structures. 

• Continue to test realistic device structures. 

• Attempt to synthesize selected types of hybrid materials. 

• Propose follow on work to the DOE Solid-State Lighting program. 

15
16

Advanced Measurement and Characterization Techniques

Shape and Crystallography of III-V Semiconductor Nanoparticles 

Principal Investigator: Phil Ahrenkiel 

Award: $120,000 

Period of Performance: October 2004 to September 2006 

Status: In Progress 

Goal 

To develop new methods for imaging and diffraction of colloidal nanoparticles. 

Investment Outcome 

Work on this project has generated a tomogram of titanium dioxide (TiO2) nanoparticles and 

improved three dimensional rendering capabilities. TiO2 was indicated as a system to which 

improved imaging methods could be applied. 

Value of the Outcome 

Nanostructured TiO2 is the electro-optically active semiconductor used in a range of solar 

energy technologies, from solar dissociation of toxic materials for waste remediation to the 

backbone of dye-sensitised, nanostructured solar cells. TiO2 nanoparticles are also used in 

numerous device applications involving transparent, conducting thin films. The optoelectronic 

properties are affected by the particle shape, and the full 3-D shape is often nearly impossible to 

determine from conventional microscopy. The team was able to generate tomograms that allow 

direct analysis of the 3-D particle shape and determination of the physical dimensions of the 

particles. 

Tomography is also being used to determine the shapes and arrangements of semiconductor 

nanoparticles. Some applications require the assembly of the nanoparticles into ordered 3-D 

arrangements for charge transport. Tomography allows visualization of the particle 

arrangements in high-symmetry orientations that would otherwise remain inaccessible. This 

detailed structural information aids the chemists who synthesize the particles and facilitates 

improved theoretical understanding. 

Knowledge Transfer 

A poster will be presented at the Materials Research Society (MRS) fall meeting, and is a great 

opportunity for exposure to numerous groups in the nanotechnology fields. 

Next Steps 

The team will gain experience or seek assistance assembling tomograms into animations that 

are annotated for distribution and presentation. 

Single-Crystal X-Ray Diffraction Facility (Capability) 

Principal Investigator: Phil Parilla 

Award: $130,000 

Period of Performance: August 2002 to July 2005 

Status: Completed 

Goal 

Strengthen core competencies in x-ray diffraction and establish a new capability to use singlecrystal diffraction. 
17

Investment Outcome 

The project team became familiar with the concepts of analysis techniques required to 

determine atomic positions based on x-ray diffraction (XRD) data. This expertise is valuable for 

interpreting and analyzing data from existing x-ray diffraction equipment and even more 

valuable when in use with a single-crystal diffractometer. 

Value of the Outcome 

NREL researchers gained valuable experience and knowledge about single-crystal diffraction. 

Single-crystal x-ray studies are key research techniques for advanced materials development 

for energy-related applications. 

Bioenergy, Biotechnology, Chemistry

Integrating Steam Pretreatment and Anaerobic Digestion: A Flexible Strategy for 

Biomass Conversion to Methane and Hydrogen (H4, H2) and Co-Products 

Principal Investigator: Stefan Czernik 

Award: $324,000 

Period of Performance: March 2003 to April 2005 

Status: Completed 

Goal 

To prove the concept that steam-exploded biomass can be fermented by microbes, yielding 

hydrogen and methane. 

Investment Outcome 

This project produced two outcomes. First, there is direct production of hydrogen from liquid 

hemicellulose-rich fraction obtained by steam explosion of corn stover. Using a natural 

inoculant obtained from the heated sludge of a local wastewater treatment plant, Stefan 

Czernik's team demonstrated that indigenous microbes were capable of fermenting the aqueous 

hydrolyzates derived from the hemicellulose fraction of the steam-pretreated corn stover. 

Biogas contained equal amounts of hydrogen and carbon dioxide. In addition to glucose, the 

natural inoculant could also utilize other sugars equally well, resulting in nearly 87% to 94% 

utilization of the glucan and xylan. Hydrogen molar yields of 2.84 and 3.0 per mole of sugar 

were obtained with hydrolyzate from neutral and acidic steam explosion, respectively. Overall, 

neutral steam explosion of the corn stover at 220°C-3 min yielded the best hydrogen production 

amongst the other conditions under investigation. Higher severity treatment resulted in 

excessive losses of sugars and formation of unwanted by-products (furfural and hydroxylmethyl-furfural). This finding strongly suggests that steam explosion is a suitable pretreatment 

technology for biomass fermentation to hydrogen. 

Second, there is direct production of hydrogen from solid lignocellulose fraction of steampretreated corn stover. Initially, using the sewage sludge consortium, the team did not succeed 

in generating hydrogen from lignocellulose within a three-week reaction time. Findings 

suggested that the inability of those microbes to produce hydrogen from the lignocellulosic 

solids was not due to the inhibition by the lignin component or other inhibitory products, but 

rather to the lack of cellulolytic microbes in the consortium, which were either not present 

initially, or became inactive during the inoculant baking process. Eventually, it was discovered 

that a thermophilic bacterium Clostridium thermocellum is able to ferment most of the 

lignocellulosic solids obtained by steam explosion of corn stover and, most likely other steamtreated biomass, thereby producing hydrogen. The hydrogen yields based on total sugar 

content were comparable to those from anaerobic fermentation of free glucose; the latter is a 

more favorable substrate, yet costly. This finding meets the goal of this DDRD project. 
18

Value of the Outcome 

The most significant outcome is that the team proved that hydrogen could be produced from 

biomass by integrating biomass steam pretreatment and anaerobic digestion. This strategy can 

be applied to both dry and wet biomass. This project develops core competency in the 

anaerobic digestion area using fermentative organism to directly produce hydrogen. As a result 

of this research, the DOE Hydrogen, Fuel Cells, and Infrastructure Program supported further 

study of anaerobic fermentation of lignocellulosic biomass as a potential technology for 

producing hydrogen from waste biomass. 

Knowledge Transfer 

• "Hydrogen production from the fermentation of corn stover biomass pretreated with a 

steam explosion process," by R. Datar, J. Huang, P-C. Maness, A. Mohagheghi, 

S. Czernik, and E. Chornet, Environmental Science and Technology (submitted). 

• A second paper is being prepared. 

Nitrogen Conversion to NOx in Biomass Thermochemical Processes 

Principal Investigator: David Dayton 

Award: $406,907 

Period of Performance: June 2002 to May 2005 

Status: Completed 

Goal 

To develop a fundamental understanding of the forms of nitrogen in biomass, and insights into 

the mechanism and kinetics of how fuel-bound nitrogen transforms to nitrogen oxide emissions 

(NOx) in biomass thermochemical conversion processes. 

Investment Outcome 

The project team’s experiments using isotopically-labeled plant samples, advanced the 

understanding of the transformation of nitrogen during biomass pyrolysis and gasification. 

Combustion experiments provided the first direct determination of the relative release of 

nitrogen oxide (NO2) and nitric oxide (NO) during biomass combustion under idealized 

laboratory conditions. Fundamental measurements like these can be used to help predict 

changes in NOx emissions during biomass/coal cofiring. 

This project has improved understanding of the forms of nitrogen in biomass, and insights into 

the mechanism of how fuel-bound nitrogen transforms to NOx in thermochemical conversion 

processes. The project team developed a way to quantitatively measure how much fuel-bound 

nitrogen is released as molecular nitrogen and NO. The team is determining how fuel-bound 

nitrogen in biomass transforms during the initial stages of pyrolysis. The hope is to expand 

these measurements to gasification/reducing conditions to see how the high temperature 

chemistry changes. Ultimately, these results can be used to help develop and validate chemical 

kinetic mechanisms to explain and predict NOx release from biomass thermochemical 

processes. 

Value of the Outcome 

Thermochemical conversion is one of the promising technologies for expanded biomass use 

being pursued through DOE R&D. Transformation of fuel-bound nitrogen during thermochemical 

conversion is the genesis of undesired emissions in biomass processes for heat, power, and 

liquid fuels production.

Increased understanding of the emissions from thermochemical conversion will provide a basis 

for improving emission abatement and control strategies, facilitating achievement of DOE 

Biomass Program goals. 
19

Localized Carrier Dynamics in Organic Semiconductor Probed via Time-Resolved 

THz Photoconductivity (TRTP) 

Principal Investigator: Randy Ellingson 

Award: $309,412 

Period of Performance: October 2004 to September 2006 

Status: In Progress 

Goal 

Organic semiconductors are expected to play a large role in future solar cell applications. The 

goal of this work was to develop a competent and advanced terahertz (THz) spectroscopy 

project at NREL, which would place the Laboratory at the forefront of this important new field. In 

addition, a flexible time-resolved THz photoconduction spectrometer will strengthen many of 

NREL’s current core programs. Developing an understanding of their microscopic carrier 

dynamics will contribute significantly to this endeavor. 

Investment Outcome 

Randy Ellingson’s team was able to implement improvements to time-resolved THz 

photoconductivity (TRTP) apparatus to improve frequency coverage and sensitivity in this first 

year, and have achieved a factor of 5-10 improvement since initially setting up the experiment. 

Work will continue on polyacenes to provide detailed understanding of the localized 

conductivity, and compare temperature dependent mobility measurements to previous time-offlight (TOF) results. 

Time-resolved photoconductivity was measured in a sample of indium phosphide (InP) 

semiconductor nanocrystals embedded in a poly-(3-hexylthiophene) (P3HT) polymer host. This 

was a demonstration of NREL’s ability to measure the complex conductivity of an arbitrary 

polymer. In addition, this work will provide a foundation for studying energy and/or charge 

transfer in hybrid QD/polymer systems or other molecular/polymer systems, such as singlewalled carbon nanotube and polymer systems. 

This project has clearly made progress on the ability to prepare poly-acene crystals, and to 

perform straightforward optical characterization of the materials; however, there was a delay 

due to the class IV laser shutdown from January through April 2005. The ultrafast time-resolved 

measurements were not possible without the use of the laser. The laser system is now 

functioning properly and the measurement systems are set up and able to acquire data. 

New knowledge includes: 

• The ability to grow tetracene-doped anthracene crystals. Such a material system has 

not been previously studied, and while this material will not be addressed as a first 

priority, it offers the potential for unique properties with regard to free carrier formation in 

organic semiconductors. 

• The ability to measure THz signals from both pure polymer as well as a C60-polymer 

blend has been demonstrated (C60 is the most common carbon buckyball, and when 

functionalized as [6,6]-phenyl C61-butyric acid methyl ester, is commonly referred to as 

PCBM). This ability allows further investigation of the effects of sample composition and 

quality on the free carrier yield and lifetimes, and should enable correlation between 

these properties and the solar cell efficiencies measured in complete cells. The recent 

success in demonstrating the PCBM concentration dependence of the apparent free 

carrier yield in the polymer blend provides a foundation for broad application of the 

technique. It is the principal investigator's opinion that the results to date have already 

established, in principle, the merit of this approach as complementary to slower 

characterization methods such as time-resolved microwave conductivity. 
20

Value of the Outcome 

The team has made excellent progress toward a reliable and powerful analytical technique for 

quantitative assessment of blended materials systems (organic/organic or inorganic/organic) for 

use in solar energy conversion. Advances in blended materials systems may provide new paths 

to advance DOE’s Solar Program goals. 

Next Steps

• Access is available to a series of samples of P3HT/C60 with varying C60 concentrations. 

This will allow study of the concentration dependence, enabling NREL to determine 

whether the apparent yield of free carriers is linear with concentration (further work is in 

progress here). 

• Annealing these samples gives better conductivity along the polymer chain, apparently 

due to improved ordering and crystallinity. 

• The team would like to take a more in-depth look at the effects of annealing on the THz 

conductivity signature.The team expects to resume characterization of the polyacenes in 

pressed-powder form, the results of which will provide information important to this 

project as well as to projects involving charge transfer in small-molecules interacting with 

inorganic semiconductor nanocrystals or single-walled carbon nanotubes. 

Nanostructured PbTe/PbSe Thermoelectric Materials 

Principal Investigator: Mark Hanna 

Award: $190,000 

Period of Performance: October 2004 to March 2006 

Status: In Progress 

Goal 

To develop a process to make a high ZT nanostructured lead telluride/lead selenide 

(PbTe/PbSe) thermoelectric material with colloidal precursors that can be scaled up to produce 

large-area thick thermoelectric devices. 

Investment Outcome 

The x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) measurements indicate 

that the lead tellurium (PbTe) nanocrystals contain free metallic lead and iodine. These 

impurities may be detrimental to the thermoelectric properties of PbTe devices made from these 

nanocrystals, so the project team investigated other nanocrystal synthesis routes. A promising 

synthesis has been identified which produces cleaner material and will be used to make PbSe 

and PbTe/PbSe core shell particles in the next quarter. 

Value of the Outcome 

Major advances in the development of nanostructured materials show promising results for 

significantly enhancing thermoelectric energy conversion efficiency as compared to more 

traditional BiTe-type materials. Development of this capability opens up new research 

opportunities for efficient energy conversion.

 
Figure 8. Transmission electron micrograph of PbSe 

nanoparticles synthesized from PbI2 and Na2Se in methanol. 

Next Steps 

Make and characterize core-shell PbTe/PbSe nanoparticles. These nanoparticles will be used 

to fabricate pellets and their mechanical and thermoelectric properties will be studied. 

Figure 9. Pressed PbTe nanoparticle pellet after annealing at 600C for 30 minutes. The 

crystal facets of the grains have rounded edges due to the higher annealing temperature. 

21
22

Biomass-Derived Nitrogen-Containing Slow Release Soil Amendments 

Principal Investigator: Kimberly Magrini-Bair 

Award: $150,000 

Period of Performance: November 2003 to March 2005 

Status: Completed 

Goal 

To develop a slow release nitrogen-containing soil amendment derived from biomass chars. If 

successful, these materials would provide a new market for renewable biomass-derived 

materials, increase soil fertility to protect water from chemical (fertilizer) runoff, and to provide 

long-term storage of carbon in soils. 

Investment Outcome 

The project team demonstrated that biomass-derived chars (chemically reacted with urea and 

pyrolysis oil to add nitrogen) enhance plant growth similar to the addition of rich nitrogen, 

phosphorous, potassium (NPK) fertilizer. They also found that adding char (raw and 

functionalized) to soil significantly enhances root growth and that char can support the growth 

and subsequent release of nitrogen-fixing bacteria into soils. 

Value of the Outcome 

These promising results provide the basis to design renewable time-release fertilizers for 

promoting above and below ground plant growth that additionally sequester carbon in the soil. 

Sustainable benefits of using these materials as targeted agricultural fertilizers are: producing 

fertilizers from renewable biomass; eliminating conventional fertilizer nitrate runoff into 

watersheds (a severe and growing water quality problem); increasing soil organic matter 

accumulation from enhanced root growth; and sequestering carbon in soils. If developed 

further, the impact of this work is a sustainable and renewable agricultural system based on 

biomass-derived fertilizers. This approach could revolutionize traditional agricultural practices, 

minimizing envirnmental impacts of conventional fertilizer use. This approach could also create 

a new market for biomass-derived materials, and enhance the economics of biorefineries – thus 

supporting DOE’s goal to create a bioindustry. 

Transition Metal Catalysis: Experiment and Theory 

Principal Investigator: Mark Nimlos 

Award: $412,756 

Period of Performance: October 2004 to September 2007 

Status: In Progress 

Goals 

• To use a close collaboration between laboratory measurements and quantum 

mechanical molecular modeling to improve our understanding of catalytic processes that 

are important in renewable energy production and utilization. 

• To develop hydrogenolysis catalysts that are capable of converting alcohols into 

alkanes. This novel chemical process is thermodynamically favored, seldom observed, 

and would introduce a new simple approach to a chemical transformation that is usually 

quite difficult. The technology could be used to convert glycerol, a byproduct of biodiesel 

production, to a high value compound. The technology could also be useful for 

converting sugars for polysaccharides into diesel fuel. Novel complexes, which have 

been developed at NREL, should be capable of catalyzing this hydrogenolysis reaction. 

The focus of this project is to demonstrate the feasibility of catalytic hydrogenolysis of 

alcohols, and perhaps more important, to demonstrate that high level quantum 

mechanical calculations can be useful in guiding the development of these catalysts. 
23

Investment Outcome 

Mark Nimlos' team obtained reasonable relative hydricites for palladium and nickel diphosphine 

complexes with ethyl (depe) and propyl bridges (depp). They also obtained reasonable 

geometries for the diethyl phosphines. Experiments showed that the methyl phosphines provide 

fairly accurate models of the diethyl compounds. However, when these calculations were 

extended to the larger ligands, accurate hydricites could not be obtained. As the bite angle of 

these ligands increases from xylenyl (depx) to diphenylether (depPE) to xanthenyl (EtXan), 

experiments showed that the hydricites increased. Calculations showed decreasing hydricites 

for complexes with these ligands. The problem is believed to arise from the large number of 

possible conformers that exist for these large ligands. In the last quarter of the fiscal year, 

model ligands were used in order to reduce the possible conformers and make the calculations 

more tractable. Diphosphine ligands were replaced with two PH3 or PMe3 ligands frozen at bite 

angles similar to the angles of the large ligands. 

The first milestone: “prepare [Pt(EtXantphos)2]

2+ and [Pd(EtXantphos)2]2+ and perform alcohol 

(C-O) hydrogenolysis studies with benzyl alcohol” has been completed. The second milestone, 

 “perform same hydrogenolysis studies with other alcohols and optimize conditions for selective 

hydrogenolysis”, is underway. 

Value of the Outcome 

Encouraging results to date indicate that this technology has the potential to provide a simple 

chemical transformation to convert glycol, a bioproduct of biodiesel production, to a high value 

compound, and to convert sugars or polysaccharides into diesel fuel. If positive results 

continue, the project may improve the economies of biodiesel. This project supports DOE goals 

in bioenergy, biofuels, which are to reduce dependence on petroleum and create a bioindustry. 

Next Steps 

Continue work on milestones, test catalysts, and conduct more detailed computations of model 

systems. 

Rapid Assignment of Metabolic Function to Genes of Saccharomyces cerevisiae

Using Metabonomics 

Principal Investigators: Arjun Singh and Mark Davis 

Award: $380,265 

Period of Performance: June 2003 to June 2005 

Status: Completed 

Goal 

• To develop a rapid method to assign function to genes by analyzing the metabolic 

profiles. 

• Identify and assign at least three biomarkers and their gene function relationships. 

• Develop a proof of concept for using nuclear magnetic resonance (NMR) and/or 

pyrolysis molecular beam mass spectrometer (PyMBMS) to rapidly assay changes in 

metabolic activity caused by genetic manipulation. 

• Identify a change in gene expression due to changes in growth conditions. 

• Two publications in refereed journals and one proposal submission in the area of 

metabonomics and gene function. 
24

Investment Outcome 

The team completed experiments using MBMS to analyze intact yeast cells and to classify three 

different pathway mutations. Experimental reproducibility was poor and much time was spent 

identifying the sources or errors. The result of these experiments indicated that it was going to 

be difficult to grow yeast strains to perform the high throughput screening experiments that were 

originally envisioned. However, Arjun Singh and Mark Davis demonstrated the utility of the 

method for identifying yeast mutations. 

The team used electrospray mass spectrometry (ESMS) to analyze cell extracts. This approach 

was chosen to increase selectivity and sensitivity and it allowed the team to focus on primary 

metabolites. The intent was to prove reproducibility of the experiment by focusing on the 

primary metabolites. This approach suffered from many of the same problems as in the MBMS 

approach. However, several sources of experimental reproducibility were identified and new 

experiments were designed to improve the high-throughput approach. 

In the last year of this project, the team started classifying multiple yeast mutations using the 

ESMS analysis of the yeast extracts. They classified 13 strains from three different metabolic 

pathways including cell wall mutations, aromatic amino acid mutations, and sulfur amino acid 

mutations. The data was encouraging because it appeared to classify the mutations as well as 

the metabolic pathway. This result was important because it demonstrated that the observed 

difference was due to changes in the metabolic pathways and not due to the yeast mutations 

being grown in a different flask. While there are still problems with day-to-day reproducibility, 

The principal investigators overcame many of the reproducibility problems with growth and 

extraction conditions. 

This approach showed that day-to day variability could be removed by performing binary 

comparisons. This method will be explored further in future work. 

Value of the Outcome 

Advances in metabolomics and metabolic profiling will enable a greater basic understanding of 

plant and single cell metabolic and biosynthetic networks especially when used in conjunction 

with other "omic" data. The high-throughput analytical methods developed during this project 

could be used to develop a more complete understanding at a molecular and genetic level of 

plant cell wall formation and deconstruction allowing the development of more efficient 

microorganisms and biomass feedstocks. The techniques developed also could be used to 

reveal interactions between microbes, enzymes, and plant constituents enabling an 

understanding of how diverse genomes interact providing for a comprehensive systems biology 

approach to understanding biological biomass conversion. 

The expertise developed under this DDRD proposal is being applied in projects with the Office 

of Science, Biological and Environmental Research (OS-BER), National Science Foundation 

(NSF), and industry pertaining to metabolic and genetic screening of plant materials. 

Pentose Transport and Assay Development 

Principal Investigator: Min Zhang 

Award: $356,618 

Period of Performance: June 2003 to March 2006 

Status: In Progress 
25

Goals 

• To establish methodologies to study structure and function relationships of xylose 

transport proteins. 

• To establish rapid and reliable assays for analysis of the kinetics of sugar transport. 

Investment Outcome 

Xylose is the second most abundant sugar available in the world and could potentially produce 

one third of the ethanol from plant biomasss feedstocks. Microbial utilization of xylose suffered 

from its low utilization rate and low product yield. Efficient utilization of xylose is the key to 

economical production of liquid transportation fuels from biomass feedstocks. This is critically 

important to EERE’s strategic goals to reduce or end dependence on foreign oil and to create a 

bioindustry (based on biorefineries). 

Results, thus far, suggested that xylE was expressed on plasmind, and that a high level of 

expression could be toxic to the cell. This is an essential step for testing xylE function. The 

team developed a growth assay method that offers high throughput screening of transport 

mutants. They also created a promoter mutant library that contains various growth rates. 

Characterization of this library is in progress. Once the library and other aspects of the system 

have been established, NREL will be able to learn the structure and function relationships of this 

important sugar transporter. 

Value of the Outcome 

Efficient utilization of xylose, the second most abundant sugar in the world, could tremendously 

expand the biomass ethanol industry. This technology is critical to the economical production of 

liquid transportation fuels from biomass feedstocks. The work potentially supports DOE goals in 

creating a bioindustry and reducing dependence on petroleum. 

Next Steps 

• Characterize the promoter mutant library. 

• Conduct site-directed mutagenesis using alanine scanning and its characterization. 

• Submit a proposal to DOE’s Office of Science Program. 

Computational Sciences

Study of Fundamental Protein/Protein Interactions Involved in Biological Energy 

Generation 

Principal Investigator: Kwiseon Kim 

Award: $381,000 

Period of Performance: October 2004 to September 2007 

Status: In Progress 

Goal 

Study via computational modeling the mechanisms governing competing protein/protein 

interactions involved in biological energy-generating processes and understand their impact on 

the rate of hydrogen production. 

Investment Outcome 

Kwiseon Kim and her team are working on establishing and documenting the method for 

studying protein interactions computationally by molecular docking. The work consists of 

building protein models, docking and screening complexes, analyzing interfaces and calculating 

binding free energies using molecular dynamics techniques. They established a method to 
26

calculate binding free energies, taking into account the translational, rotational, and vibrational 

components of binding entropy, polar and apolar solvation energy, and complex interaction 

enthalpy. They have also determined improved force field parameters for the metalloclusters in 

ferredoxin and hydrogenase using density functional theory and Natural Bond Orbital methods. 

Value of the Outcome 

Interprotein surface analysis combined with further computational analysis can be used to 

screen proposed mutations to yield a rational enzyme engineering strategy. The 

parameterization method developed here can be used to establish more accurate force fields 

for other molecules of general technological interest. A computational biochemist post doc has 

been hired, thus increasing computational modeling capability in biological sciences. 

Developing efficient means of producing hydrogen (H2) from renewable sources is a compelling 

challenge on the path toward national energy security. Photobiological H2 generation promises 

to be a clean, cost-effective means of meeting that challenge. This project addresses an 

important aspect of this nascent technology by significantly enhancing our fundamental 

understanding of protein interactions, with the goal of improved electron transport essential to 

efficient algal H2 production. 

Next Steps 

• Complete quantum mechanical parameterization of metalloclusters involved in the 

system and testing in molecular dynamical simulations. 

• Further develop the method for calculation of binding free energy. Refine solvation 

model and protein structural features for consistent interfacial engineering.

• Analyze Brownian dynamics simulations of C. reinhardtii ferredoxin and hydrogenase 

model proteins for the estimates of association rate constants.

Electric and Hydrogen Technologies and Systems

Electrical Model Development and Validation for Distributed Resources 

Principal Investigator: Ben Kroposki 

Award: $149,998 

Period of Performance: October 2004 to September 2005 

Status: Completed 

Goals 

• To conduct research necessary for developing and validating advanced models for 

multiple distributed resources (DR). 

• To develop the in-house capability to understand and model the electrical effects of 

multiple distributed resources on the distribution system, and determine the impacts of 

large penetrations for DR. 

• To develop collaboration with the Colorado School of Mines (CSM) in electrical 

engineering research. 
27

Investment Outcome 

Ben Kroposki's team completed: 

• A literature search of electrical models for distributed resources. This information adds 

to NREL's knowledge base on the types of models for electric power systems and 

distributed resources. 

• Evaluation and selection of software programs for simulating electrical performance of 

distributed resources and electric power systems. This work allowed NREL to invest 

significantly in a new modeling tool for understanding electric power systems operation. 

• Model development for a variety of distributed resources at the NREL DER test facility. 

This accomplishment established new models for understanding the electrical 

performance of DR. Some of these models are not available in the literature and will be 

valuable for understanding the performance and operations of inverter based DR. 

Value of the Outcome 

This project developed new capabilities in conducting electrical modeling of distributed 

resources and electric power systems using power system computer design software (PSCAD). 

This model allows for advanced simulation of electric power systems and allows users to 

develop models of individual components. New models were developed for inverter based DR 

(i.e. PV, wind, fuel cell). This project also established a new collaborative effort between NREL 

and CSM in electrical power systems. 

As a result of this work, follow on work to develop models for advanced power electronics and 

electrical interfaces will be supported in FY06 through the DOE Distributed Energy Program and 

the California Energy Commission Public Interest Energy Research Program. 

Prototype Renewable Planning Model (RPM) 

Principal Investigator: Ben Kroposki 

Award: $500,000 

Period of Performance: May 2005 to July 2007 

Status: In Progress 

Goal 

To develop a preliminary assessment tool, the Renewable Planning Model (RPM), to integrate 

basic resource availability (i.e. solar irradiation, wind resource, and biomass feedstocks) with 

infrastructure elements (i.e. power distribution system, roads) and constraints onto a single 

geographic interface. 

Investment Outcome 

The project team created a basic web-based geographic information system (GIS) map viewer 

and interface with HOMER program, received distribution system load data from Xcel Energy, 

and added overlay capability to GIS mapper. They also developed a tool that will show basic 

resource availability–solar irradiation and wind resource. NREL has sought technical expertise, 

and data from a utility on its distribution system to ensure that the tool is a usable product. 

Near-term, the project will establish a more complete prototype before the product is shared on 

a larger scale. Long-term, this project could be expanded to work with a variety of utilities and 

energy analysis. 
28

Value of the Outcome 

This tool will allow DOE and other decision makers to assess the deployment potential of a 

range of renewable energy sources based on geographic resources as well as transmission and 

distribution capacities, road proximity, terrain suitability, regional incentives, etc. It will be an 

efficient tool for the evaluation of local, regional, or national impacts of technical and economic 

goals as well as regulatory and demand-based influences. 

Next Steps 

The next step is to focus on a specific example situation (siting commercial PV systems) and to 

develop a protoype that will examine the specifics of that issue. 
29

Appendix A: Acronyms and Symbols 

AC – Alternating Current 

ANL – Argonne National Laboratory 

Au – Gold 

AWEA – American Wind Energy 

Association 

BNL – Brookhaven National Laboratory 

BSCL – Biomass Surface Characterization 

Laboratory 

CdMgTe – Cadmium Magnesium Telluride 

CEC – California Energy Commission 

CELIV – Current Extraction by Linearly 

Increasing Voltage 

CH4 – Methane 

C-O – Alcohol 

CSM – Colorado School of Mines 

CSP – Concentrating Solar Power 

CSU – Colorado State University 

C60 – (The most common carbon 

buckyball) 

DDRD – Director’s Discretionary Research 

and Development (program) 

depPE – Diphenylether 

depx – Xlenyl Diphenylether 

DER – Distributed Energy Resources 

DOE – Department of Energy 

DR – Distributed Resources 

EC – Electrochromic 

ECC – Electrochemical Capacitor 

EIA – Energy Information Administration 

En – Ethylenediamine 

EPA – Environmental Protection Agency 

ESMS – Electrospray Mass Spectrometry 

Etxan – Xanthenyl 

eV – Electron Volt 

FAD – Flavin Adenine Dinucleotide 

GaAs – Gallium Arsenide 

GIS – Geographic Information System 

GPC – Gel Permeation Chromatography 

GPRA – Government Performance and 

Results Act 

HPLC – High Pressure Liquid 

Chromatography 

H2 – Hydrogen 

ICF – Integrated Planning Model 

InGaAs – Indium Gallium Arsenide 

InP – Indium Phosphide 

IPM – Integrated Planning Model 

ITO – Indium Tin Oxide 

K – Potassium 

LCMS – Liquid Chromatography Mass 

Spectrometry 
30

LEDs – Light Emitting Diodes 

MARKEL – (EPA’s wind model) 

MBMS – Molecular Beam Mass 

Spectrometer 

MIT – Massachusetts Institute of 

Technology 

MRS – Materials Research Society 

N – Nitrogen 

NADP – Nicotinamide Adenine Dinucleotide 

Phosphate 

Na2Se – Sodium Selenide 

NBO – Natural Bond Orbital 

NEMS – National Energy Modeling System 

NiO – Nickel Oxide 

NIST – National Institute of Standards 

Technology 

NMR – Nuclear Magnetic Resonance 

NO – Nitric Oxide 

NOx – (Encompasses all nitrogen oxide 

emissions: NO, N2O, and NO2) 

NPK – Nitrogen, Phosphorous, Potassium 

NRL – Naval Research Laboratory 

NSF – National Science Foundation 

NSOM – Near-field Scanning Optical 

Microscope 

N2 – Nitrogen Oxide 

OLEDs – Organic Light Emitting Diodes 

OPV – Organic Photovoltaic 

OS-BER – Office of Science, Biological and 

Environmental Research 

P – Phosphorous 

P3HT – Poly-(3-hexylthiophene) 

PbI2 – Lead Iodide 

PbSe – Lead Selenide 

PbTe – Lead Telluride 

PCBM – (C60 is the most common carbon 

buckyball, and when functionalized as: 

[6,6]-phenyl C61-butyric acid methyl ester; 

it’s commonly referred to as PCBM.) 

PECVD – Plasma Enhanced Chemical 

Vapor Deposition 

PNNL – Pacific Northwest National 

Laboratory 

PSCAD – Power Systems Computer Aided 

Design (software) 

PyMBMS – Pyrolysis Molecular Beam Mass 

Spectrometer 

PV – Photovoltaics 

QD – Quantum Dot 

QDSL – Quantum Dot Superlattices 

RFF – Resources for the Future 

RPM – Renewable Planning Model 

RuO2 x H2O – Amorphous Hydrous 

Ruthenium Oxides 

SEDS – Stochastic Energy Development 

Systems 

SERF – Solar Energy Research Facility 

SiO2 – Silicon Dioxide 

SSL – Solid State Light 

SWNT – Single-Walled Nanotubes 

Ta2O5 – Tantalum Oxide 
31

TEM – Transmission Electron Microscope 

THz – Terahertz 

TiO2 – Titanium Dioxide 

TOF – Time-of-Flight 

TRTP – Time-Resolved THz 

Photoconductivity 

U of W – University of Wisconsin 

WFO – Work for Others 

WinDS – Wind Deployment System 

WO3 – Substoichemetric (The W is not fully 

oxidized.) 

XPS – X-ray Photoelectron Spectroscopy 

XRD – X-ray Diffraction 

ZnTe – Zinc Telluride 

ZT – (A dimensionless figure of merit for 

thermoelectric materials. ZT=S2

σT/k – S is 

the Seebeck coefficient, σ is the electrical 

conductivity, k is thermal conductivity, and T 

is the temperature.) 
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Director’s Discretionary Research and Development Program: 

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