Bioenergy describes any energy source based on biological matter — everything from an dung cooking fire or a biomass power station to ethanol-based car fuel. Unlike oil, coal or gas, bioenergy counts as a renewable energy option, because plant and animal materials can be easily regenerated.
At present, bioenergy accounts for the majority of renewable energy produced globally. The term biofuels is sometimes used interchangeably with bioenergy, though more commonly it's used specifically to describe liquid bioenergy fuels such as biodiesel a diesel substitute and bioethanol which can be used in petrol engines.
Bioenergy is often considered to be environmentally friendly because, in theory, the CO2 released when plants and trees are burned is balanced out by the CO2 absorbed by the new ones planted to replace those harvested.
However, the environmental and social benefits of bioenergy are hotly contested — especially in the case of biofuels, which are often produced from food crops such as palm oil, corn or sugar. Another issue heavily associated with biomass production is greenhouse gas emissions from land management and land use change.
These refer to emissions of greenhouse gases especially CO2, CH4, and N2O resulting from agricultural inputs, management practices, and land use changes associated with production of biomass. These emissions can be divided into direct and indirect sources. Direct emissions refer to those resulting from land clearing, agricultural inputs such as fertilizers , or management practices undertaken in the process of growing or harvesting a biomass crop. Indirect emissions are associated with market-driven land use change.
These are the emissions that occur when forests, grasslands, or other ecosystems are cleared to produce crops or other commodities to compensate for land that has been diverted to energy production. The effects are difficult to quantify or attribute, making indirect emissions from land use change ILUC a very controversial subject.
Finally, it is important to remember that biomass markets will add value to biomass products, residues, and productive lands. This value will help improve the economic viability of working lands and act as a positive incentive to help preserve farms and forests from the accelerating threat of urban and suburban sprawl — the greatest land use impact.
Bioenergy Biofuels and Biomass. How will we efficiently grow, collect, transport, and convert the bulky, dispersed biomass required for cellulosic biofuels? Why aren't more farmers collecting agricultural residue or growing crops to make biofuels right now?
Can we use municipal solid waste and other urban wastes to produce fuel? What is the Department of Energy doing to help the U. When will we see the substantial commercial production of cellulosic ethanol and hydrocarbon biofuels? Various techniques are currently being developed to produce second generation biofuels. However, it is uncertain when such technologies will enter production on a significant commercial scale. The conversion of cellulose to ethanol involves two steps. The cellulosic and hemicellulosic components of the plant material are first broken down into sugars, which are then fermented to obtain ethanol.
The first step is technically difficult, although research continues on developing efficient and cost-effective ways of carrying out the process. Lignin cannot be converted to ethanol, but it can provide the necessary energy for the conversion process.
Gasification is a technique that converts solid biomass such as wood into a fuel gas. Gasifiers operate by heating biomass to high temperatures in a low-oxygen environment releasing an energy-rich gas. This gas can be burned in a boiler, used in a gas turbine to generate electricity.
Biodiesel production is essentially concentrated in the European Union. Table 1: Biofuel production by country, Large-scale production of biofuels from crops requires large land areas to grow them, which generates increasing competition for natural resources, notably land and water. Crop yields per hectare vary widely depending on the type of crop, the country and the production system. Currently, ethanol production from sugar cane and sugar beet produces the highest yields per hectare.
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