The application of bio-char (charcoal or biomass-derived black carbon (C)) to soil is pro- posed as a novel approach to establish a significant, long-term, sink for atmospheric carbon dioxide in terrestrial ecosystems. Apart from positive effects in both reducing emissions and increasing the sequestration of greenhouse gases, the production of bio-char and its application to soil will deliver im- mediate benefits through improved soil fertility and increased crop production. Conversion of biomass C to bio-char C leads to sequestration of about 50% of the initial C compared to the low amounts retained after burning (3%) and biological decomposition (<10-20% after 5-10 years), therefore yielding more stable soil C than burning or direct land application of biomass. This efficiency of C conversion of biomass to bio-char is highly dependent on the type of feedstock, but is not significantly affected by the pyrolysis temperature (within 350-500 ◦ C common for pyrolysis). Existing slash-and- burn systems cause significant degradation of soil and release of greenhouse gases and opportunies may exist to enhance this system by conversion to slash-and-char systems. Our global analysis revealed that up to 12% of the total anthropogenic C emissions by land use change (0.21 Pg C) can be off-set annually in soil, if slash-and-burn is replaced by slash-and-char. Agricultural and forestry wastes such as forest residues, mill residues, field crop residues, or urban wastes add a conservatively estimated 0.16 Pg C yr −1 . Biofuel production using modern biomass can produce a bio-char by-product through pyrolysis which results in 30.6 kg C sequestration for each GJ of energy produced. Using published projections of the use of renewable fuels in the year 2100, bio-char sequestration could amount to 5.5-9.5 Pg C yr −1 if this demand for energy was met through pyrolysis, which would exceed current emissions from fossil fuels (5.4 Pg C yr −1 ). Bio-char soil management systems can deliver tradable C emissions reduction, and C sequestered is easily accountable, and verifiable.

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Bio-char sequestration in terrestrial ecosystems - a review

The world is confronted with the twin crises of fossil fuel depletion and environmental degradation. The indiscriminate extraction and consumption of fossil fuels have led to a reduction in petroleum reserves. Petroleum based fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain region of the world. Therefore, those countries not having these resources are facing a foreign exchange crisis, mainly due to the import of crude petroleum oil. Hence it is necessary to look for alternative fuels, which can be produced from materials available within the country. Although vegetative oils can be fuel for diesel engines, but their high viscosities, low volatilities and poor cold flow properties have led to the investigation of its various derivatives. Among the different possible sources, fatty acid methyl esters, known as Biodiesel fuel derived from triglycerides (vegetable oil and animal fates) by transesterification with methanol, present the promising alternative substitute to diesel fuels and have received the most attention now a day. The main advantages of using Biodiesel are its renewability, better quality exhaust gas emission, its biodegradability and the organic carbon present in it is photosynthetic in origin. It does not contribute to a rise in the level of carbon dioxide in the atmosphere and consequently to the green house effect. This paper reviews the source of production and characterization of vegetable oils and their methyl ester as the substitute of the petroleum fuel and future possibilities of Biodiesel production.

Biodiesel production through the use of different sources and characterization of oils and their esters as the substitute of diesel: A review

A 10-year US Department of Energy-sponsored research program designed to evaluate and develop switchgrass ( Panicum virgatum ), a native perennial warm-season grass, as a dedicated energy crop is reviewed. The programmatic objectives were to identify the best varieties and management practices to optimize productivity, while developing an understanding of the basis for long-term improvement of switchgrass through breeding and sustainable production in conventional agroecosystems. This research has reduced the projected production cost of switchgrass by about 25% ($8–9 Mg −1 ) through yield increases of about 50% achieved through selection of the best regionally adapted varieties; through optimizing cutting frequency and timing; and by reducing the level (by about 40%) and timing of nitrogen fertilization. Breeding research has made further gains in productivity of switchgrass that exceed the historical rate of yield improvement of corn. Studies of soil carbon storage under switchgrass indicate significant carbon sequestration will occur in soils that will improve soil productivity and nutrient cycling and can substantially augment greenhouse gas reductions associated with substituting renewable energy for fossil energy. Collaborative research with industry has included fuel production and handling in power production, herbicide testing and licensing, release of new cultivars, and genetic modifications for chemical coproduct enhancement. Economically based life cycle analyses based on this research suggest that switchgrass produced for energy will compete favorably both as an agricultural crop and as fuel for industry.

Development of switchgrass (Panicum virgatum) as a bioenergy feedstock in the United States.

State renewable energy electricity policies: An empirical evaluation of effectiveness

Agricultural residues such as corn (Zea mays L.) stover are a potential feedstock for bioenergy and bio-based products that could reduceU.S. dependence on foreign oil. Collection of such residues must take into account concerns that residue removal could increase erosion, reduce crop productivity, and deplete soil carbon and nutrients. This article estimates where and how much corn stover can be collected sustainably in the USA using existing commercial equipment and estimates costs of that collection. Erosion constraints to collection were considered explicitly, and crop productivity and soil nutrient constraints were considered implicitly, by recognizing the value of residues for maintaining soil moisture and including the cost of fertilizer to replace nutrients removed. Possible soil carbon loss was not considered in the analysis. With an annual production of 196 million Mg of corn grain (about9.2 billion bushels), the USA produces 196 million Mg of stover. Under current rotation and tillage practices, about 30% of this stover could be collected for less than $33 per Mg, taking into consideration erosion and soil moisture concerns and nutrient replacement costs. Wind erosion is a major constraint to stover collection. Analysis suggests three regions of the country (central Illinois, northern Iowa/southern Minnesota, and along themore » Platte River in Nebraska) produce sufficient stover to support large biorefineries with one million Mg per year feedstock demands and that if farmers converted to universal no-till production of corn, then over 100 million Mg of stover could be collected annually without causing erosion to exceed the tolerable soil loss.« less

Current and potential U.S. corn stover supplies.

The Policy Analysis System (POLYSYS) is a national simulation model of the US agriculture sector which can incorporate agricultural supply and demand and related modules to estimate agricultural production response, resource use, price, income, and environmental impacts of projected changes from an agricultural baseline. The framework recursively incorporates linear programming, econometric, and process models to estimate an impact path resulting from changes imposed on a baseline scenario and its underlying assumptions. POLYSYS estimates crop production and supply at a disaggregated regional level, whereby the 48 contiguous states are subdivided into 305 geographic regions with relatively homogeneous production characteristics. POLYSYS is capable of estimating a wide range of policy alternatives and economic and environmental conditions and simulations may be tailored to a variety of specific analytical needs. This paper presents a broad overview of the structure and approach of the POLYSYS model with emphasis on biomass and bioenergy related applications of the model.

Biomass and bioenergy applications of the POLYSYS modeling framework

Biomass Feedstock Availability in the United States: 1999 State Level Analysis

Using a stochastic version of the POLYSYS modeling framework, an examination of projected variability in agricultural prices, supply, demand, stocks, and incomes is conducted for corn, wheat, soybeans, and cotton during the 1998–2006 period. Increased planting flexibility introduced in the 1996 farm bill results in projections of significantly higher planted acreage variability compared to recent historical levels. Variability of ending stocks and stock-to-use ratios is projected to be higher for com and soybeans and lower for wheat and cotton compared to the 1986-96 period. Significantly higher variability is projected for corn prices, with wheat and soybean prices also being more variable. No significant change in cotton price variability is projected.

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Estimating price variability in agriculture: implications for decision makers

POLYSYS is used to estimate US locations where, for any given energy crop price, energy crop production can be economically competitive with conventional crops. POLYSYS is a multi-crop, multi-sector agricultural model developed and maintained by the University of Tennessee and used by the USDA-Economic Research Service. It includes 305 agricultural statistical districts (ASD) which can be aggregated to provide state, regional, and national information. POLYSYS is being modified to include switchgrass, hybrid poplar, and willow on all land suitable for their production. This paper summarizes the preliminary national level results of the POLYSYS analysis for selected energy crop prices for the year 2007 and presents the corresponding maps (for the same prices) of energy crop production locations by ASD. Summarized results include: (1) estimates of energy crop hectares (acres) and quantities (dry Mg, dry tons), (2) identification of traditional crops allocated to energy crop production and calculation of changes in their prices and hectares (acres) of production, and (3) changes in total net farm returns for traditional agricultural crops. The information is useful for identifying areas of the US where large quantities of lowest cost energy crops can most likely be produced.

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Daryll E. Ray

Papers

Biomass and bioenergy applications of the POLYSYS modeling framework

Biomass Feedstock Availability in the United States: 1999 State Level Analysis

Estimating price variability in agriculture: implications for decision makers

Economic Analysis of Energy Crop Production in the U.S. - Location, Quantities, Price, and Impacts on Traditional Agricultural Crops

Toward a Pro-Middle Farm Policy: What Will It Take to Ensure a Promising Future for Family Farming?