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Heating and cooling of buildings consume approximately 15% of all energy used in the United States. Such a large energy demand is primarily due to heating and cooling of the entire building space to temperature setpoints usually between 21.1 °C (70 °F) and 23.9 °C (75 °F). However, even with such a narrow range of temperature setpoints, more than 20% of the occupants do not feel thermally comfortable due to individual differences (e.g. age, gender, clothing, or physiology). The personal thermal management techniques, which create a local thermal envelope around a human body instead of heating or cooling the entire building space, have the potential to greatly reduce the building energy consumption and to enhance thermal comfort of individuals. In this study, a portable thermoelectric energy conversion unit (TECU) that converts electricity into cooling and heating energy is developed. The TECU supplies cool air (in the cooling mode) or warm air (in the heating mode) to regulate the thermal comfort of a human body. The cool or warm air is supplied through a tree-like rubber tube network that is knitted into a thermoregulatory undergarment. To achieve a cooling/heating target that provides satisfactory thermal comfort, the required cooling/heating power supply from the TECU is determined first while a theoretical model is then developed to guide the design of the TECU. To minimize the TECU weight and make it suitable for portable applications, relationships between weight and thermal resistances of commercial off-the-shelf heat sinks are established first, and a method to find the minimal weight of heat sinks for the TECU is then developed. This methodology is also applicable for other applications where heat sink weight needs to be minimized. The thermal manikin tests demonstrate that 24.6 W of personal cooling power and 18.5 W of personal heating power are achieved by using the TECU. [ABSTRACT FROM AUTHOR]

The cultivation of energy cane throughout the Southeastern United States may displace grazed pastures on organic soil (Histosols) to meet growing demands for biofuels. We combined results from a field experiment with a biogeochemical model to improve our understanding of how the conversion of pasture to energy cane during early crop establishment affected soil GHG (CO 2 , CH 4 , and N 2 O) exchange with the atmosphere. GHG fluxes were measured under both land uses during wet, hot and cool, dry times of year, and following a fertilization event. We also simulated the impact of changes in precipitation on GHG exchange. Higher fertilization of cane contributed to greater emission of N 2 O than pasture during warmer and wetter times of the year. The model predicted that energy cane emitted more nitrogen than pasture during simulated wetter than drier years. The modeled emission factor for N 2 O was 20 to 30-fold higher than the default value from IPCC (1%), suggesting that the default IPCC value could dramatically underestimate the consequences of this land conversion on the climate system. Predicted soil CH 4 and CO 2 fluxes were higher in pasture than energy cane, and this difference was not affected by increasing precipitation. Model simulations predicted that soils under first year cane emit more GHGs than pasture, particularly during wet years, but this difference disappeared two years after energy cane establishment. Our results suggest that management practices may be important in determining soil GHG emissions from energy cane on organic soils particularly during the first year of cane establishment. [ABSTRACT FROM AUTHOR]

Abstract: For woody biomass to make a significant contribution to the United States' energy portfolio, harvesting contractors must economically harvest and transport energywood to conversion/processing facilities. We conducted a designed operational study in the Coastal Plain of North Carolina, USA with three replications of three treatments to measure harvesting productivity and costs when utilizing woody biomass. The treatments were: a conventional roundwood only harvest (control), an integrated harvest in which merchantable roundwood was delivered to mills and residuals were chipped for energy, and a chip harvest in which all stems were chipped for energy use. The harvesting contractor in this study typically delivers 2200–2700 t of green roundwood per week and is capable of wet-site harvesting. Results indicate that onboard truck green roundwood costs increased from 9.35 $ t−1 in the conventional treatment to 10.98 $ t−1 in the integrated treatment as a result of reduced felling and skidding productivity. Green energy chips were produced for 19.19 $ t−1 onboard truck in the integrated treatment and 17.93 $ t−1 in the chip treatment. Low skidding productivity contributed to high chip costs in the integrated treatment. Residual green biomass was reduced from 18 t ha−1 in the conventional treatment to 4 and 3 t ha−1 in the integrated and chip treatments, respectively. This study suggests that until energywood prices appreciate substantially, loggers are unlikely to sacrifice roundwood production to increase energywood production. This research provides unique information from a designed experiment documenting how producing energywood affects each function of a harvesting system. [Copyright &y& Elsevier]

The National Aeronautics and Space Administration Glenn Research Center (GRC) has an extensive history in dynamic energy conversion dating back to the early 1960s. This legacy puts the GRC at the forefront of nuclear power systems using thermodynamic power cycles such as Stirling and Brayton. The advantages of dynamic energy conversion include high efficiency, long life, and scalability to high power. These attributes make Brayton and Stirling power cycles an ideal solution for nuclear energy conversion. [ABSTRACT FROM AUTHOR]

Background: Woody biomass is one of the most abundant biomass feedstocks, besides agriculture residuals in the United States. The sustainable harvest residuals and thinnings alone are estimated at about 75 million tons/year. These forest residuals and thinnings could produce the equivalent of 5 billion gallons of lignocellulosic ethanol annually. Softwood biomass is the most recalcitrant biomass in pretreatment before an enzymatic hydrolysis. To utilize the most recalcitrant lignocellulosic materials, an efficient, industrially scalable and cost effective pretreatment method is needed. Results: Obtaining a high yield of sugar from recalcitrant biomass generally requires a high severity of pretreatment with aggressive chemistry, followed by extensive conditioning, and large doses of enzymes. Catchlight Energy's Sugar process, CLE Sugar, uses a low intensity, high throughput variation of bisulfite pulping to pretreat recalcitrant biomass, such as softwood forest residuals. By leveraging well-proven bisulfite technology and the rapid progress of enzyme suppliers, CLE Sugar can achieve a high yield of total biomass carbohydrate conversion to monomeric lignocellulosic sugars. For example, 85.8% of biomass carbohydrates are saccharified for un-debarked Loblolly pine chips (softwood), and 94.0% for debarked maple chips (hardwood). Furan compound formation was 1.29% of biomass feedstock for Loblolly pine and 1.10% for maple. At 17% solids hydrolysis of pretreated softwood, an enzyme dose of 0.075 g Sigma enzyme mixture/g dry pretreated (unwashed) biomass was needed to achieve 8.1% total sugar titer in the hydrolysate and an overall prehydrolysate liquor plus enzymatic hydrolysis conversion yield of 76.6%. At a much lower enzyme dosage of 0.044 g CTec2 enzyme product/g dry (unwashed) pretreated softwood, hydrolysis at 17% solids achieved 9.2% total sugar titer in the hydrolysate with an overall sugar yield of 85.0% in the combined prehydrolysate liquor and enzymatic hydrolysate. CLE Sugar has been demonstrated to be effective on hardwood and herbaceous biomass, making it truly feedstock flexible. Conclusions: Different options exist for integrating lignocellulosic sugar into sugar-using operations. A sugar conversion plant may be adjacent to a CLE Sugar plant, and the CLE Sugar can be concentrated from the initial 10% sugar as needed. Concentrated sugars, however, can be shipped to remote sites such as ethanol plants or other sugar users. In such cases, options for shipping a dense form of sugars include (1) pretreated biomass with enzyme addition, (2) lignocellulosic sugar syrup, and (3) lignocellulosic sugar solid. These could provide the advantage of maximizing the use of existing assets. [ABSTRACT FROM AUTHOR]

Abstract: The U.S. Energy Independence and Security Act of 2007 mandates the use, if produced, of 6.06 × 1010 L of advanced biofuels by 2022. The objective of this study is to determine the ethanol price necessary for a biorefinery to breakeven when using switchgrass as the single feedstock to produce ethanol. A holistic model that encompasses acquisition of land use services, feedstock production, harvest, harvest machine investment, feedstock logistics (storage, transportation), biorefinery location and size, and biorefinery investment is constructed and used to determine breakeven ethanol price. The model was solved for each of three biomass to ethanol conversion rates (250, 334, and 417 L of ethanol Mg−1 of biomass) and each of three biorefinery investment cost estimates ($2, $4, and $6 × 108 for a biorefinery with annual capacity of 379 × 106 L). Breakeven ethanol prices ranged from $0.44 L−1 with a conversion rate of 417 L of ethanol Mg−1 and an investment cost of $2 × 108, to $0.72 L−1 with a conversion rate of 250 L Mg−1 and an investment cost of $6 × 108. Improving the efficiency of conversion from 250 to 334 L Mg−1 decreases the estimated breakeven cost by $0. 07 L−1. Improved conversion efficiency results in a reduction of the total quantity of feedstock required and in the cost to deliver feedstock. Most of the cost reduction follows from reductions in land required (rent), and biomass harvest, storage, and transportation costs. [Copyright &y& Elsevier]

The article looks at the U.S. Department of Energy Advanced Research Project Agency - Energy (ARPA-E) program that awards research grants for clean energy ventures, with particular focus on projects incorporating biological research. An overview of several ARPA-E projects is provided, including investigations into the role of the carbon cycle in energy conversion, the plants engineered to replace oil (PETRO) experiment that builds on the process of plant photosynthesis to produce biomass energy, and the electrofuels program that involves the conversion of carbon dioxide into liquid fuel using microorganisms.

Abstract: Next generation hydrocarbon biofuels have the potential to fulfill not only the biofuels production mandate of the Energy Independence and Security Act (EISA) of 2007, but also would not have to be exempted from the EISA-mandated increase in the corporate average fuel economy. Producing “green gasoline”, “green diesel” and “green jet fuel” from non-food lignocellulosic feedstocks such as forest waste and agricultural residue, and energy crops such as short rotation trees and perennial grasses grown on marginal or abandoned cropland will substantially lower greenhouse gas emissions and will not affect food prices. In this paper the development of the new paradigm of green gasoline from lignocellulose will be reviewed, the potential pathways to these infrastructure-compatible fuels will be discussed, and critical process design needs will be outlined. [Copyright &y& Elsevier]

AbstractCost-effective implementation of microalgae as a solar-to-chemical energy conversion platform requires extensive system optimization; computer modeling can bring this to bear. This work uses modified versions of the U.S. Environmental Protection Agency's (EPA's) Environmental Fluid Dynamics Code (EFDC) in conjunction with the U.S. Army Corp of Engineers' water-quality code (CE-QUAL) to simulate hydrodynamics coupled to growth kinetics of algae (Phaeodactylum tricornutum) in open-channel raceways. The model allows the flexibility to manipulate a host of variables associated with raceway-design, algal-growth, water-quality, hydrodynamic, and atmospheric conditions. The model provides realistic results wherein growth rates follow the diurnal fluctuation of solar irradiation and temperature. The greatest benefit that numerical simulation of the flow system offers is the ability to design the raceway before construction, saving considerable cost and time. Moreover, experiment operators can evaluate the impacts of various changes to system conditions (e.g., depth, temperature, flow speeds) without risking the algal biomass under study. [ABSTRACT FROM AUTHOR]

Historical information concerning the development of high-temperature gas-cooled reactors in the USA and Russia is presented. The reactor facilities MHTGR (USA), VG-400 (Russia), VGM (Russia), GT-MGR (Russia, USA), and at the Fort St. Vrain nuclear power plant (USA) are described. The US programs for developing innovative high-temperature nuclear reactor technologies are examined. It is shown that the Russian and US technological developments for the fuel, reactor system, energy conversion system, and fission-product transport are similar. [ABSTRACT FROM AUTHOR]

Abstract: Loblolly pine plantations are the most important source of forest products in the US and the slash remaining after conventional harvest represents a significant potential source of bioenergy. However, slash removal in intensive harvests might, under some circumstances, reduce site productivity by reducing soil organic matter and associated nutrients. Two complimentary studies in the Gulf Coastal Plain of the southeastern US were designed to test whether harvest intensity (level of biomass removal) could have a negative long-term impact on site productivity. Harvesting tree crowns in addition to the merchantable bole had a negative impact (18%) on pine biomass accumulation by age 7–10 years on 15 of 19 research blocks. Sites at risk of harvest-induced reductions in productivity were relatively unproductive prior to harvest and had low soil phosphorus (P) concentrations. Intensive harvesting, fertilization, and chemical control of non-crop vegetation were all energy efficient; the additional biomass energy gained through these practices was two-orders of magnitude greater than the energy needed to conduct the activities. Harvest of slash for bioenergy in the Gulf Coastal Plain of the southeastern US has the potential to reduce productivity on infertile soils, but fertilization has the potential to restore and even improve productivity on those sites in an energy-efficient way. [Copyright &y& Elsevier]

Negative environmental consequences of fossil fuels and concerns about petroleum supplies have spurred the search for renewable transportation biofuels. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. We use these criteria to evaluate, through life-cycle accounting, ethanol from corn grain and biodiesel from soybeans. Ethanol yields 25% more energy than the energy invested in its production, whereas biodiesel yields 93% more. Compared with ethanol, biodiesel releases just 1.0%, 8.3%, and 13% of the agricultural nitrogen, phosphorus, and pesticide pollutants, respectively, per net energy gain. Relative to the fossil fuels they displace, greenhouse gas emissions are reduced 12% by the production and combustion of ethanol and 41% by biodiesel. Biodiesel also releases less air pollutants per net energy gain than ethanol. These advantages of biodiesel over ethanol come from lower agricultural inputs and more efficient conversion of feed-stocks to fuel. Neither biofuel can replace much petroleum without impacting food supplies. Even dedicating all U.S. corn and soybean production to biofuels would meet only 12% of gasoline demand and 6% of diesel demand. Until recent increases in petroleum prices, high production costs made biofuels unprofitable without subsidies. Biodiesel provides sufficient environmental advantages to merit subsidy. Transportation biofuels such as synfuel hydro-carbons or cellulosic ethanol, if produced from low-input biomass grown on agriculturally marginal land or from waste biomass, could provide much greater supplies and environmental benefits than food-based biofuels. [ABSTRACT FROM AUTHOR]

Focuses on the primary factors that limit the potential size of a biomass-energy industry in the U.S. Effect of inadequate rainfall on biomass yield; Major crop-based processes for producing bioenergy products; Reasons behind the non-adoption of crop fermentation as a process for producing ethanol.

• Wave energy for United States coastal waters is assessed using WaveWatchIII hindcast. • New wave energy resource attribute parameters are proposed. • Frequency, directional, and temporal variability of the wave energy are characterized. • The resource attributes corroborate with distinct regional wave climate features. The wave energy resource is characterized and assessed for coastal waters of the United States to evaluate regional opportunities and constraints for wave energy converter (WEC) projects. Partitioned wave parameters generated from a 30-year WaveWatch III model hindcast are used to estimate the total wave energy potential as an annual available energy (AAE), which is a theoretical annual energy production per unit energy capture length without considering energy conversion losses. The distribution of AAE by peak period, wave direction, month, and year is quantified using summary statistics, including peak period spread, AAE -weighted period, AAE -directionality coefficient, and inter-annual and seasonal temporal variability. Geographical distributions of the AAE and these five resource attributes delineate distinct wave energy resource regions within United States coastal waters, where different opportunities and constraints may influence regional energy planning, WEC project development, and WEC conceptual design. [ABSTRACT FROM AUTHOR]

Hydrogen can play a key role in the ongoing ‘energy transition’ to sustainable energy, and the formation of the Hydrogen Council aims to raise its profile and position hydrogen among the key solutions worldwide [ see page 1 ]. [ABSTRACT FROM AUTHOR]

As part of President Barack Obama''s $29.5 billion fiscal year 2012 budget for the Department of Energy, the DOE is proposing to reduce funding for the Hydrogen and Fuel Cell Technologies program by more than 40% (nearly $70 million), and completely stop funding for the Solid State Energy Conversion Alliance (SECA) program. This comes as DOE plans to spend $3.2 billion on energy efficiency and renewable energy programs, and jumpstart the US domestic nuclear energy industry. [Copyright &y& Elsevier]

The author comments on energy research and development (R&D) and the trends in the U.S. energy policies from 1970s to the 21st century. He notes that the momentum built in the R&D underlying the utilization of the alternate energy sources during the 1970s and other viable energy conversion approaches was dented when oil prices fell below $10 per barrel in the 1980s. He cites the need for a bi-partisan energy R&D policy that can withstand cyclical forces caused by political and economic events.

The US Department of Energy has selected two more projects for its Solid State Energy Conversion Alliance (SECA) Program portfolio. These will be led by UTC Power, in partnership with Delphi, and by Rolls-Royce Fuel Cell Systems (US) Inc. The Rolls-Royce project will include work at Ohio''s Stark State College Fuel Cell Prototyping Center, which is also supported through a National Science Foundation grant. [Copyright &y& Elsevier]

The article offers news briefs on environmental and medical related topics. Leaders of more than 290 colleges and universities in the U.S. have pledged to reduce or offset all their greenhouse gas emissions. The possibility of China to stop growing food crops to make biofuels is announced. The Center for Applied Genomics in Pennsylvania can continue operations after settling a lawsuit filed by deCODE Genetics Inc.

The article reports on the plan of the U.S. Department of Energy (DOE) to create two research centers that will focus on biofuels development. According to the author, the project, which has a budget allocation of $25 million a year in a span of five years, will be composed of multidisciplinary teams that will study the existing and emerging developments of biofuels. In addition, the scope of the research will focus on basic studies of microbes, their development and fermentation processes. Stanford University plant biochemist Chris Somerville stated that DOE's change of priority is anticipated to generate more developments in research projects.

This article examines the status of research being undertaken by the U.S. Agricultural Research Service (ARS) Subtropical Products Laboratory in Winter Haven, Florida on converting citrus peel waste into fuel ethanol, as of April 2006. In Florida alone, citrus processing yields about 5 million tons of wet waste annually, or 1.2 million tons of dry waste. The research, then led by Karel Grohmann, was eventually discontinued because the enzymes needed to fuel the process were expensive, and gas, at the time, was relatively cheap. In 2004, Bill Widmer, an ARS chemist at Winter Haven, picked up where Grohmann left off. With the help of a cooperative research and development agreement partner, Widmer and his scientific team first modified the process to cut the amount of enzyme required to convert citrus-waste carbohydrates to sugars and ethanol.