Biomass Power is way to go

Hobart Mercury
Saturday 16/5/2009 Page: 6

FOR two main reasons, we must seek alternatives to fossil fuels. First, by burning these carbon sources, which were generated millions of years ago, at a rate faster than the earth can reabsorb the carbon dioxide emitted, we are causing global warming. And, second, we will, sooner or later, run out of these amazing energy-dense fuels that have driven modern industrialisation and development.

One potential solution to both of these problems is biofuels. Although fossil fuels, loosely speaking, are biofuels in that they were produced by plants and algae a long time ago, when we talk about biofuels we really mean crops that are grown specifically to make fuel that can be used immediately.

The range of biofuels is enormous because virtually any kind of crop can be used and processed in several ways. Starches in grains, like corn, can be fermented into ethanol. Cellulose, the main component of wood or straw, can be converted by enzymes to ethanol. Oils, in grains such as canola, or in micro-algae, can be converted to biodiesel.

Ethanol and biodiesel can be burnt directly as fuel in specially designed or modified internal combustion engines. Another path to take is the burning of biofuels in simpler, unprocessed forms, such as wood or straw, to generate electricity, which could then be used to charge batteries in electric cars. Although biofuels were initially seen as a save-the-world technology, the reality seems somewhat less perfect.

The biggest problem with biofuels is that there simply is not enough arable land on this planet to grow enough food and fuel to satisfy our appetites. Given the way the global economy works, this might even lead to people starving in developing countries while grain is diverted to run cars to run kids to football matches in our part of the world.

So, for biofuels to be seriously considered as an alternative to fossil fuels, we need to know the most efficient way they can be used. That way, whatever land we do use to produce them, the negative effects can be minimised and the benefits, in terms of offsetting climate change, can be maximised. A new study, just published by a group of researchers from the United States and published in the latest issue of the journal Science, was designed to achieve this objective.

The researchers compared the production of ethanol from cellulose, probably the best way to make ethanol, with the production of electricity using biomass at the power plant. They took into account all the fossil fuels that went into the production of the biofuel, the production of the vehicles-either internal combustion or electric - and the efficiencies of all the steps.

Largely because an electric motor is about three times more efficient than a combustion engine per hectare of crop grown, the use of biomass-electricity and electric cars gives 80% more transportation kilometres than the liquid fuel-combustion engine system. The biomass-electric system also had twice as large an impact on reducing greenhouse gases per hectare of land cultivated.

Given the advances in battery technology that are being achieved, and that electric vehicles are quiet and clean, the study really suggests we should be developing our biofuels and transport system in this direction.