Renewable Energy

Agricultural biofuels

The word biofuel comes from the word biomass (recently living organisms or their metabolic byproducts such as manure from cows). This is a renewable energy source, unlike other natural resources such as petroleum, coal, and nuclear fuels. Like coal and petroleum, biomass is a form of stored solar energy. The energy of the sun is captured through the process of photosynthesis in growing plants.

Agricultural products specifically grown for use as biofuels include corn and soybeans (mainly in the United States), flaxseed and rapeseed (mainly in Europe) sugar cane in Brazil, palm oil in South-East Asia and jatropha (not an agricultural product) in India. Biodegradable outputs from industry, agriculture, forestry and households can be used like straw, timber, manure, rice husks, sewage, biodegradable waste, and food leftovers. These can be converted to a biogas through anaerobic digestion. Biomass used as fuel often consists of underutilized types, like chaff and animal waste. The quality of timber or grassy biomass does not have a direct impact on its value as an energy-source.

Unlike other forms of renewable energy, biofuels do not reduce the amount of greenhouse gases in the atmosphere. Burning biofuel produces carbon dioxide and other greenhouse gases. The carbon in biofuels was recently extracted from atmospheric carbon dioxide by growing plants, so burning it does not result in a net increase of carbon dioxide in the Earth's atmosphere. Therefore, many people believe that a way to reduce the amount of carbon dioxide released into the atmosphere is to use biofuels to replace non-renewable sources of energy. Simply Biofuels do not reduce greenhouse gases when they have become a fuel, instead when it was alive (as a plant or animal) it had reduced the amount of grenhouse gases. Also it does not emit any greenhouse gases, except when it is being made. Yet the amount of gas emitted is still lower than how much the living thing reduced.  Dried compressed peat is also sometimes considered a biofuel. However, it does not meet the criteria of being a renewable biofuel. Though more recent than petroleum or coal, on the time scale of human industrialisation, peat is a fossil fuel and burning it does contribute to atmospheric CO2.

Much research is being done about the use of microalgae as an energy source, with applications for biodiesel, ethanol, methanol, methane, and even hydrogen. Use of hemp is increasing, but politics restrain it. In some industrialized countries like Germany, food is cheaper than fuel compared by price per joule, mostly because fuel is taxed more than food. Central heating units supplied by food-grade wheat or maize are available. The production of biofuels to replace oil and natural gas is in active development, focusing on the use of cheap organic matter (usually cellulose, agricultural and sewage waste) in the efficient production of liquid and gas biofuels which yield high net energy gain. One advantage of biofuel over most other fuel types is that it is biodegradable, and so relatively harmless to the environment if spilled.