Kathmandu, December 6:

Global warming has been a much debated issue in recent times. Scientists and researchers are putting their hard effort to find a way out in reducing greenhouse gas emission.

Sometime back, biofuel was envisioned an alternative to fossil fuel. But some scientists have raised serious doubts whether it can really be an alternative to reducing greenhouse gas emissions and increasing energy security.

Biofuel can be broadly defined as solid, liquid, or gas fuel consisting of or derived from biomass. Biomass can also be used directly for heating or power.

Biofuel is considered by some of the researchers a means of reducing greenhouse gas emissions and increasing energy security by providing an alternative to fossil fuels. However, Nobel Laureate Paul Crutzen published findings that the release of Nitrous Oxide (N2O) among the commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), can contribute as much or more to global warming than fossil fuel savings due to global cooling. Crops with less nitrogen demand, such as grasses and woody coppice species have more favou-rable climate impacts.

Biofuels are used globally and biofuel industries are expanding in Europe, Asia and the Americas. The most common use for biofuels is in automotive tra-nsport. Biofuel can be produced from any carbon source that can be replenished rapidly like plants. Many plants and plant-derived materials are used for biofuel manufacture.

Source of biofuel

Biomass is material derived from recently living organisms, which includes plants, animals and their by-products. For example, manure, garden waste and crop residues are all sources of biomass. It is a renewable energy source based on the carbon cycle, unlike any other natural resources such as petroleum, coal, and nuclear fuels.

Agricultural products specifically grown for biofuel production include corn, switch grass, and soybeans, primarily in the US; rapeseed, wheat and sugar beet in Europe; sugar cane in Brazil; palm oil and miscanthus in South-East Asia; sorghum and cassava in China; and jatropha in India and Nepal.

Hemp has also been used as a biofuel. Biodegradable outputs from industry, agriculture, forestry and households can be used for biofuel production, either using anaerobic digestion to produce biogas, or using second generation biofuel processes like straw, timber, manure, rice husks, sewage, and food waste.

The use of biomass fuels can therefore contribute to waste management as well as fuel security and help prevent climate change, though alone they are not a comprehensive solution to these problems.

Liquid biofuels have been used since the early days in the car industry. Nikolaus August Otto, the German inventor of the internal combustion engine, conceived his invention to run on ethanol. Rudolf Diesel, the German inventor of the diesel engine, designed it to run on peanut oil. Henry Ford originally designed the Ford Model T, a car produced in 1903-1926, to run completely on ethanol. However, when crude became cheaply available, cars began using fuels derived from mineral oil, petroleum or diesel.

Nevertheless, before World War II, biofuels were seen as providing an alternative to imported oil. Germany powered its vehicles using a blend of petrol with alcohol fermented from potatoes called Reichskraftsprit. In Britain, grain alcohol was blended with petrol by the Distillers Company under the name Discol and marketed through Esso’s affiliate Cleveland.

After the war, cheap Middle East oil lessened interest in biofuels. But the oil shocks of 1973 and 1979 increased interest from governments and academics. The counter-shock of 1996 again reduced oil prices and interest.

In the US, all cars manufactured since 1988 are required to be compatible with fuels containing at least 20 per cent ethanol E20 fuel, and with minor modifications these cars can use 85 per cent ethanol blended with petroleum E85 fuel. Since around 2000 renewed interest in biofuels has been seen.

Biofuels and other forms of renewable energy aim to be carbon neutral. This means that the carbon released during the use of the fuel through burning to power transport or generate electricity, is reabsorbed and balanced by the carbon absorbed by new plant growth. These plants are then harvested to make the next batch of fuel. Carbon neutral fuels lead to no net increases in atmospheric carbon dioxide levels, which means that global warming need not get any worse. In practice, biofuels are not carbon neutral. This is because energy is required to grow crops and process them into fuel. Examples of energy use du-ring the production of biofuels include: fertilizer ma-nufacture, fuel used to po-wer machinery, and fuel used to transport crops and fuels to and from biofuel processing plants. The amount of fuel used during biofuel production has a large impact on overall gre-enhouse gas emissions savings achieved by biofuels.