Balancing the Use of Crop Residues for Biofuels with Impacts on Soil and Greenhouse Gases

by Jessica Bass

The use of crop residues as a second-generation source of biofuels may hold potential to help the United States fulfill its 2022 goal production quota outlined in the 2007 Energy Independence and Security Act. Yet, this annual accumulation plays an important role toward maintaining soil organic carbon (SOC) stocks and reducing soil erosion, protecting field health to sustain year-after-year of yields. Adler et al. (2015) use the DayCent biogeochemical model to analyze the costs and benefits of crop residue removal and use based upon its impact on crop yield, SOC content, and N2O emissions, over the course of twenty years. They examined these relationships with respect to a variety of anticipated treatment options, including: a baseline condition with no residue removal, a sample of 50% residue removal without any replacements, 50% residue removal with a nitrogen replacement equivalent to the amount removed, and a 50% residue removal and equivalent application of a high-lignin fermentation byproduct (HLFB). Continue reading

Large Suburban Carbon Footprints Negate GHG Benefits of Urban Areas

by Dan McCabe

Jones and Kammen (2014) performed a remarkably thorough analysis of the average household carbon footprint (HCF) for nearly every US zip code and examined how dozens of different variables affect greenhouse gas (GHG) emissions. The authors’ analysis used detailed data from the nationwide Residential Energy Consumption Survey, the National Household Travel Survey, and other sources. Their model used these surveys to estimate local emissions due to components such as electricity, housing, transportation, and food, then evaluated possible correlations with 37 independent demographic variables. Continue reading

Are Electric Vehicles Really Worth The Higher Costs?

by JP Kiefer

Electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and fuel cell vehicles all offer promising alternatives to the conventional vehicle in reducing greenhouse gas emissions. These alternatives may not be as beneficial as they seem on first glance, however. While electric, hybrid-electric, and fuel cell vehicles all promise to minimize greenhouse gas emissions from their daily use, Gau and Winfield (2012) point out that each vehicle’s life cycle assessment needs to be computed before jumping to the conclusion that hybrid vehicles minimize greenhouse gas emissions. The life cycle assessment analyzes the greenhouse gas emissions from two cycles: a vehicle life cycle that includes vehicle assembly, maintenance, dismantling, and recycling and a fuel life cycle that consists of fuel extraction, processing, distribution, storage, and use. These alternative vehicles are the products of a larger volume of greenhouse gas emission from the vehicle life cycle due to additional energy consumption involved with the batteries and other additional parts that go into the more advanced technologies. Electric, hybrid electric, and plug-in hybrid vehicles can also contribute to greenhouse gas emissions when the energy used to charge the batteries does not come from a clean energy source. Gau and Winfield calculate that alternative vehicles do consume less energy than conventional vehicles, which consume an estimated 3600kJ/km in their life time, compared to a mere 2250kJ/km by hybrid electric vehicles or 3000kJ/km by extended range electric vehicles. Continue reading

Oil Palm Plantation Boom in Indonesia

by Chieh-Hsin Chen

The anticipated depletion of fossil fuel has caused the production of alternative fuel sources to become an extremely important field of industry. Many less developed countries in South East Asia promote mass production of biofuel crops as a primary export. Palm oil, used in cooking as well as biofuel, is one of the main exports from Indonesia. The high demand of palm oil has led to a rapid increase of oil palm plantations, leading also to massive deforestation. Riau Province is one of the largest oil palm producing regions. From 1990s to 2012, there has been a significant decrease of forest in the region due to the boom of oil palm plantations. Ramdani and Hino (2013) analyze satellite imagery and greenhouse gas emissions from different time periods to determine the scale of deforestation. The results show that in the Riau Province, the oil palm industry rapidly increased from 1990 to 2000, with transformation of tropical forest and peat land as the primary source of emissions. Continue reading