Biofuels, bonus or bust?

A few years ago biofuels looked like one answer to rising fuel prices. The idea was to grow sugar crops, such as sugar beet, and starchy plants, such as corn, to produce ethanol by fermentation. Alternatively, oily crops like soybeans and rapeseed can provide a diesel-like fuel oil.

Many manufacturers now rate their engines to accept a certain proportion of biodiesel. Most will accept fuels that are 5% biodiesel (B5), and many will go further. John Deere, for example, says fuels up to B20 can be used with all of its Stage IIA/Tier 3 engines. Perkins' aim is to certify all of its engines up to B100.

One caution is that biodiesel is not a like-for-like substitute for petroleum diesel. With prolonged use, biodiesel can damage seals and gaskets, and it can also degrade crankcase oils. It also degrades, especially if stored incorrectly, and delivers slightly different performance than does petroleum diesel.

Just as the industry is adapting to legislative mandates, however, the rationale behind biofuels is being questioned. One problem is that land previously used for food crops now supports bio fuel crops, which has contributed to the worldwide rise in food prices. Another concern is that forested areas have been cut down to plant bio fuel crops, which is hardly a positive environmental step.

Additionally, biofuels are not ‘carbon neutral'. Their cultivation requires machines and chemicals, which means additional energy consumption and emitted carbon dioxide. Their net benefit is a controversial argument, and one that engine manufacturers are quite wisely steering clear of.