Indeed, How Green are Biofuels?

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Written by Sabrina Deparine

Tuesday, 01 September 2009 10:58

Page views: 5647

Country: Asia

While in the process of searching for a good topic on biofuels for this week’s feature on BiofuelsHub, I came across an article entitled “How Green Are Biofuels?”. Admittedly, the article did perk my curiosity primarily because it details the pros and cons and other information about each type of biofuel feedstock.

Indeed, How Green are Biofuels?

Ethanol, one type of biofuels, can actually be derived from several kinds of feedstock. In most cases, it is produced through the fermentation of sugar crops, grains, biomass, and other starches. The following are some of the most popular feedstock being used for ethanol production along with their pros and cons and other details:

• Sugarcane – This is the choice of feedstock in Brazil and in the Philippines. Sugarcane is considered as an efficient feedstock because it is able to yield around 650 to 700 gallons of ethanol per acre. This translates to about 6000 to 6500 liters of ethanol per hectare. In terms of greenhouse gas emissions, sugarcane feedstock produces 4 to 12 kilograms of carbon dioxide per mega joule of energy produced. These emissions already include those produced and emitted from growing, harvesting, and refining phases to the burning of the ethanol fuel. Technically, this carbon dioxide emission figure is better than that of regular gasoline which emits 94 kilograms per mega joule of energy produced. During the planting stage, sugarcanes require high volumes of fertilizers and water but it only requires medium-scale volumes of pesticide and other energy inputs. Best of all, technology required for ethanol production from sugarcane feedstock are readily available and there is no limitation as to where it can be grown.

• Corn – This is the primary feedstock used in the United States. In fact, 95% of ethanol in the U.S. market is made from corn feedstock. It provides an average ethanol yield of about 400 gallons per acre (3,700 liters per hectare). The main reason why the yield is quite low for corn feedstock is because only the starchy part or component of the plant (in this case, the kernel) can be converted to ethanol fuel. In terms of greenhouse gas emissions, corn feedstock can emit as much as 81 to 85 kilograms of carbon dioxide per mega joule of energy produced. It also requires high amounts of water, fertilizer, pesticide, and other forms of energy to grow. By far, the only advantage is that the technology requirements to convert corn to fuel are readily-available and relatively cheap.

• Switch grass – This is highly-favorable for use as ethanol feedstock because it requires low amounts of water, fertilizer, pesticide and other energy inputs to grow. It also has a commendable figure in terms of greenhouse gas emissions, producing -24 kilograms of carbon dioxide per mega joule of energy produced. Most of all, switch grass is not a food crop so it deviates from the issue of ethanol competing against the food supply. This has the capacity to yield about 1,150 gallons per acre per year (10,600 liters per hectare). However, the technology and methodology requirements to convert switch grass to fuel is not yet fully-developed; hence, it is not yet readily-available.

• Other Biomass (e.g. wood chips, agricultural wastes, forest wastes and others) – This is another commendable feedstock because it has low greenhouse gas emission figures. The amount of carbon dioxide emitted per unit of energy produced depends on the type of biomass used and the process employed to convert it to fuel. In terms of energy requirements, biomass requires only low amounts of water, fertilizer, and pesticide. This is also more environment-friendly because it recycles wastes and turns them into something useful. At present, the popularity of biomass as ethanol feedstock is growing but technologies still have to improved and developed.

Based on these comparisons, it can be said that the Filipinos do not have anything to worry about with the mandate on biofuels because the Philippines is on the right track in terms of ethanol and biofuel developments. The country uses sugarcane and biomass as some of the most common feedstock for ethanol production. These are commendable and highly-recommended feedstock.