Biofuels

Biofuels have been championed as environmentally-friendly sources of power that help to tackle climate change. However, the report by the Organization for Economic Cooperation and Development (OECD) said biofuels may "offer a cure that is worse than the disease they seek to heal".

Introduction

Concentrations of greenhouse gases (GHGs) in the Earth’s atmosphere have become a global concern because of their potential to affect long-term climate changes. About 82% ofthe United States' GHG emissions are fromthe combustion of fossil fuels used to generate electricity and operate vehicles. Other emissions are from methane, (Applied Energy, Volume 71, Issue 1, January 2002,Pages 15-30). On another hand, US agriculture's contribution to air pollutant as a consumer of energy is small, as agricultural crop, livestock and poultry production accounts for only about 1% of direct energy use. However, the production agriculture accounts for about 7% of annul net GHG emissions (US Department of Agriculture, 2004a). Increase in agricultural productivity and conservation can reduce energy intensity of agricultural production and pollution. These last two sentences were very confusing. Are they really necessary? It seems like the main point you want to make starts in the following sentence.Recent studies show that replacing fossil energy with renewable energy, like biofuels, is an important way of reaching the climate policy goals. (Soil and Tillage Research, Volume 61, Issues 1-2, August 2001, Pages77-92). Maybe start right here! -->There is a significant opportunity to reduce pollutants and GHG emissions by using biofuels. Like biodiesel, biofuels have many desirable environmental properties. They are non-toxic and biodegradable, and biodiesel exhaust emits less toxic air emissions, carbon monoxide and particular matter than petroleum diesel (Graboski and McCormick, 1998). Biofuels also have advantages that the plants grown each year to produce the fuel sequester carbon, which offsets the carbon released during fuel combustion (National Renewable Energy Laboratory, 1998). Reread and reword this last sentence.

Types of biofuels

Today, there are various sources for the production of biofuels. Although all the transport fuels can be classified in fossil fuels, the process chains for all transport fuels are different since which types of primary sources are needed(see the table below).

Process chains for fuel production

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First generation biofuels

Bioethanol, the most commonly biofuel feedstock, is a fuel generally produced by the action of microorganisms and enzymes through the fermentation of any biological feedstock, which contains appreciable amounts of sugar or materials that can be converted into sugar such as starch or cellulose.

Second generation biofuels

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Pathways of Different biofuels

Socio-economic benefits and problems

In the United States, biofuel production has not proven to be broadly economically feasible

Case Study—Biofuels in China

Biofuels have become a broad debate in many countries' energy policies since it covers many aspects, such as energy security, food security, climate change mitigation, and international biofuel development. With 20 percent of world's population and 10 percent of its arable land, the center debate of biofuel production ins China is the conflict between food security and energy crops.

In January 2007, China’s State Forestry Administration (SFA) and the oil company PetroChina signed an agreement of developing diversity of potential energy crops, an oil-bearing plant, Jatropha. Jatropha curcas has considered as a high potential biodiesel feedstock in China since it grows on marginal land in Southwest China, and thus avoids the completion with food system. Southwest China, including Guizhou Province, Sichuan Province, and Yunnan Province, is the official target area for Jatropha production in China(see table below). Especially for Yunnan Province, it has significantly more land available for Jatropha production than neither Guizhou nor Sichuan Province. Therefore, Yunnan may be the p province capable of achieving the National Development and Reform Commission (NDRC)'s goal: to expand Jatropha plantations to 10 million mu in each Southwest province in China.

Estimate Current and Planned Jatropha Area in Southwest China by Province

Future studies

The amount of subsidy, the extent of biofuel penetration into the energy market and the rate of technical progress are the key considerations in the future biofuel prospects. In this study, the only form of subsidy considered is in the form of a carbon price which may not be subsidy at all but rather a reflection of the future externality cost of GHG emission into the atmosphere. Namely, if a prospect offset 95% of the carbon created from energy equivalent amount of fossil fuel then at a US$40/MT carbon price this amounts to a US$38/MT implicit subsidy and relative to a wood price in the vicinity of US$25 to US$30/MT, this substantially offsets the purchase price to a biofeedstock user(Agiculure as a Producer and Consumer of Energy, J.Outlaw,2005). Energy market penetration of biofuels is similarly important. Biofuels can penetrate when new plants are built or older plants are retrofit. New power or petroleum refining plants are needed as existing plants are retired or as demand for energy use grows(Potential for Biofuel-based Greenhouse Gas Emission Mitigation: Rationale and Potential,2004). Therefore, progress in biofeedstock yields whether at the farm or in the form of conversion ratios to energy products as energy products will be important to maintain a competitive role.