News and Trends

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Researchers from the US Department of Energy (DOE) Joint BioEnergy Institute (JBEI) recently identified bisabolane as a plausible biofuel alternative to fossil-fuel-based Number2 (D2) diesel. Bisabolane is an organic compound belonging to a class of compounds called terpenes. Terpenes are usually found in plants and are conventionally used as fragrances or flavorings. The JBEI scientists also reported that they have engineered a bacterial strain (Escherichia coli) and a yeast strain (Saccharomyces cerevisiae), which can produce its precursor, bisabolene. Bisabolene can then be easily hydrogenated to produce bisabolane.

Bisabolane is reported to have a similar chemical structure to diesel (i.e. bisobolane has a carbon length of C15 while diesel has an average carbon length of C16). The researchers also found that it has better fuel properties in terms of freezing point and cloud point. These better fuel properties were attributed to the compound's branched and cyclic chemical structure. After identifying bisobolane as a feasible diesel alternative, the researchers then developed a method for producing the diesel alternative. In their method, they genetically engineered the above-mentioned bacterial and yeast strains to perform a mevalonate pathway that will produce bisabolene (bisabolane's precursor). However,the researchers are still currently trying to improve the process by genetically engineering the cells to directly produce bisobolane, instead of bisobolene. The price of bisabolane is estimated at $6 per gallon, which is still more expensive than diesel. However,due its superior properties and renewable nature, it drives researchers to further investigate and improve this new alternative. The full paper is published in the journal, Nature Communications (URL above).

Related chemical information about bisabolane:

Researchers from University of Minnesota and the University of Wisconsin (United States) recently discussed the potential of increasing bioenergy crop yields through a more efficient agricultural production, without the increase in land allocation for bioenergy crops. By grouping different areas around the world that share similar water and climate conditions, the researchers were able to quantify the impacts of improving distribution of high-yielding cultivars, inputs, irrigation and the application of best-in-class management practices for 20 common agricultural biofuel crops. Based on the groupings, they were able to identify "hotspots"of low yielding agriculture (i.e. locations where agriculture yields are comparably lower to other locations in the group).

They found that if efficient agricultural practices are applied in these hotspots, it could annually increase bioethanol and biodiesel production by approximately 112.5 billion liters and 8.5 billion liters, respectively. This study, according to the researchers,is intended to be an important new resource for scientists and policymakers alike—helping to more accurately understand spatial variation of yield and agricultural intensification potential, as well as employing these data to better utilize existing infrastructure and optimize the distribution of development and aid capital. The full study is published in the journal, Environmental Research Letters (URL above).

Energy Crops and Feedstocks for Biofuels Production

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Researchers from the Department of Agricultural and Biological Engineering (ABE), University of Illinois (United States) recently investigated the effect of regional weather patterns on the development and evaluation of biomass feedstock harvest systems. Since agricultural operations are weather dependent, weather can significantly impact the feedstock production as well as subsequent storage and supply activities.

In their study, the researchers determined the effect of weather on the harvest systems through the inclusion of the probability of working day (PWD) parameter in the BioFeed modeling framework (i.e. an existing mathematical model that determines the best production system for energy crops and  provides decision support to farmers). The PWD is defined as the fraction of days in a specific period that are suitable for field operations, and its value depends on a number of weather-related parameters, such as rainfall, snow depth, soil temperature, and soil moisture content.

Using the PWD-incorporated BioFeed framework,the researchers conducted model simulations for Miscanthus (a potential biomass feedstock (grass) for biofuel production) plantations located in Illinois. Based from the results, the researchers found that incorporating weather effects on the model through PWD increases the cost of harvesting and decreases the biorefinery capacity in a given region. In the case of Illinois, with an average winter PWD of 35%, they found that the total operating cost increased by 38% and the biofuel capacity decreased by 45%. For the total operating cost, its increase could be offset by an increase in machinery; however, it would result to an increase in capital cost of 34%. These results, according to the researchers, emphasized that the consideration of weather impacts on farm productivity is extremely important when considering system design and operations. The full paper is published by the American Society of Agricultural and Biological Engineers (URL above).

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Scientists from the AgriLife Research Center, Texas A&M University (United States) report the identification of key genes which control flowering in the sorghum plant. Sorghum [Sorghumbicolor (L.) Moench] is a robust, drought-tolerant "C4 grass" which is grown for grain and forage, providing an important food source in many food-insecure areas in the world. The stalks and leaves of the sorghum plant also provides lignocellulosic biomass resources, which can be harnessed for biofuel-ethanol production. A high biomass productivity of biofuel feedstocks is important to make it a competitive bioenergy crop, and biomass production may in turn, be regulated by the flowering period of the plant.

The discovery of genes which regulate flowering in the sorghum plant opens up new possibilities for increasing the bioenergy-potential of sorghum biomass for biofuels production. The scientists identified four key genes for regulation of flowering in the sorghum plant, "Ma1", "Ma2", "Ma3" and "Ma4".   According to biochemist, Dr. John Mullet, "We were able to identify a gene in sorghum that controls flowering in response today length, and we discovered that the gene is regulated by the plant's internal 'clock' and light enabling the plant to flower at approximately the same date each growing season". They explained that delayed flowering in the sorghum plant can divert plant metabolism toward higher biomass productivity. The Ecoseed website highlights the implication of the research as follows: "With these genetic markers now identified, grower scan begin to figure out a way to breed hybrid sorghum strains that would flower at optimal times to ensure the plant gives out maximum yield during harvest time". The research results are published in the Proceedings of the National Academy of Sciences (PNAS) (URL above).

Related information:
Youtube video: "Energy-sorghum Flowering Gene Discovered"

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Increasing demand in food and energy, compounded with the dwindling fossil energy reserves, has prompted land usage competition between food and bioenergy crops. In order to minimize the impending land competition, scientists from Aberystwyth University (United Kingdom) recently reviewed land competition between food and bioenergy crops and proposed suitable bioenergy crops capable of maintaining "harmonized" land usage.

In their review, the researchers set a vision for suitable bioenergy crops in terms of four major gains for society: (1) a reduction in carbon emissions from the substitution of fossil fuels with appropriate energy crops, (2) a significant contribution to energy security by reductions in fossil fuel dependence, (3) new options that stimulate rural and urban economic development, and (4) reduced dependence of global agriculture on fossil fuels.   In addition, food-related factors are taken into consideration in the selection of a suitable bioenergy crop such as: (1) food requirements, (2) the economics of energy crops on less favorable land, (3) gains in productivity of crop and animal production, (4) the effects of reducing meat production, and (5) the economic value of bioenergy production in terms of its value for energy and the value of carbon emissions saved.

According to the researchers, there must be a shift of bioenergy crops to dedicated perennial crops, in order to avoid the impending land competition.Compared to the first generation bioenergy crops (such as grain, tuber and oilseed crops), these energy crops do not require agrochemical inputs, help avoid the destruction of native forests and minimize competition with primary food production. The full paper is published in the journal, Global Change Biology: Bioenergy (URL above).

Biofuels Processing

Aviation fuels,or jet fuels, are specialized types of fuel used in aircraft. Due to their vital role in the flight of aircraft, aviation fuels follow stringent quality guidelines compared to other fuels (as shown in the ASTM (American Society for Testing and Materials) D-1655 standard for aviation fuel). Consequently, the production cost of aviation biofuel is higher compared to other transport biofuels. Recently, researchers from AliphaJet, Inc. and University of Louisville (United States) developed a novel method in the production of aviation fuel from renewable products, such as plant and animal triglycerides and/or fatty acids.

In this new process, the fatty acids (released from the fats present in the biomass feedstock) undergoes catalytic decarboxylation (i.e.the release of carbon dioxide) to produce hydrocarbons. Depending on the fatty acids present, the process produces olefins (unsaturated hydrocarbons) or paraffins(saturated hydrocarbons).  For aviation biofuels, the saturated hydrocarbons of a specified carbon chain length is the target product.  The process is reported to be viable for meeting the needs of not just the aviation industry, but of the entire petrochemical industry.

However, in production of aviation fuel (i.e. which are saturated hydrocarbons), small amounts of hydrogen gas in the decarboxylation process) must be introduced in order to convert the produced olefins intro saturated hydrocarbons.  According  to the researchers, this process is more cost-effective (compared to conventional methods of aviation fuel production), in terms of capital and processing cost,  because of the reduction in the use of hydrogen and less complex processing facilities.

Biofuels Policy and Economics

As countries gradually veer away from fossil fuels and shift to biomass-based renewable energy, there is concern regarding the supply of global wood resources.   Wood reportedly accounts for 67 percent of the world's renewable energy supply, and its use is still increasing. In some European countries, wood demand is said to be very high; there are reports which mention that demand surpasses supply by 600 percent. Thus, many investors look to invest in tree plantations in the tropics. If managed well, it could be a welcome development for tropical countries, specially third-world countries Benefits include job/investment creation, climate change mitigation and environmental conservation. However, researchers from the International Institute for Environment and Development (UK) discussed a possible negative side in this positive development for developing tropical countries. The researchers argued in their paper there is a risk that these plantations can displace poor and marginalized communities from land they have tended to for generations but do not have a formal claim over. Thus, through this paper, the researchers warn policymakers to consider the harm it would do to the food security and the livelihoods of the world's poorest and most vulnerable people if governments lease large areas of land for fuel wood plantations. The researchers also added that countries in the tropics should develop wood for local energy security,not to export it to fuel other countries' energy deficits at the expense of their own people. The full paper is available at the International Institute for Environment and Development website (URL above).