More on biofuels.

• Author: Firn, Richard D.

"The future of biofuels is cellulosic fuels ... they do not compete for prime cropland ... and even restore degraded lands ...." I was saddened by these quotes from Raya Widenoja's response to Heinrich Smith's timely criticism of biofuels [January/February "From Readers"] because the quotes were based on the new hype that cellulosic fuels will simply use "waste" biomass. There is no waste cellulose. Every cellulose molecule is fuel for some organism and that organism undoubtedly lies at the bottom of some food chain. Consequently the use of crop waste, forest waste, or any other carbon source currently unexploited by humans simply increases the share of the global carbon cycle that humans use. Can you seriously argue that there would be no ecological consequences?

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Worldwatch biofuels research associate Raya Widenoja responds: Second-generation biofuels based on biomass from perennial crops such as prairie grasses, or from woody crops or wood waste, can be used to provide energy and build carbon levels in soils without requiring external fertilization, pesticides, or irrigation. Biomass from many perennial grasses can also be produced and harvested sustainably on fragile and erodable soils that would not tolerate most food crops. Biofuels can also be derived sustainably from waste materials such as sawdust, scrap wood, and urban waste. The emphasis here, however, is definitely on "can" Second-generation biofuels can also be grown in large monocrops using high fertilizer and chemical inputs and irrigation in systems that are unsustainable.

Biofuels can certainly be derived from "agricultural wastes" that are actually not wastes but needed compost sources. The prime example of this is corn stover. Because corn is such a fertilizer- and water-intensive crop, research indicates that removing more than a quarter of the stalks and leaves (from most soils) will degrade soil quality. There are, however, other agricultural wastes that can be used sustainably for energy production without soil degradation, such as citrus peels, nut shells, spoiled fruit, and rice straw. The stalks of sweet...