On the greenhouse effect Monday, March 12, 2007

C.G. Moghe is well justified in calling for a careful discussion of Indonesia's biofuel drive (The Jakarta Post, March 6), but some scientific clarification is required in the interests of informed debate.

In particular, his concern about additional waste heat from burning biofuels, thus adding significantly to the greenhouse effect, is based on a misunderstanding and is therefore misleading. Waste heat is not bad as the greenhouse gases" emitted from burning fossil fuels. Here is why:

The solar energy reaching the Earth every minute is far greater than the heat produced every year by human fuel use. Yet the Earth maintains a near-constant temperature because it radiates a similarly vast amount of energy back out to space.

The balance is dynamic. Any fluctuations are smoothed out over time through the thermodynamic principle that the hotter the body, the more energy it radiates and the faster it cools. On a planetary scale, direct heating caused by human fuel use is short-lived, undetectable and immaterial.

Greenhouse gases, in contrast, accumulate. Well over half of all the carbon dioxide derived from human use of fossil fuels is still in circulation. These surplus gases work like an extra blanket, stifling the Earth's capacity to radiate heat away. This raises the global temperature as a new energy balance is reached. And with greenhouse gases, a little means a lot.

If carbon dioxide levels ever amounted to one percent of the atmosphere simply by following current trends the Earth would reach boiling point. Inefficient fuel use, therefore, is a concern not because it generates heat but because it generates greenhouse gases wastefully. If we had truly carbon-neutral fuels, then by definition these would not contribute to the greenhouse effect by adding extra carbon dioxide to the atmosphere.

This is not the place to review the merits of different biofuels. However, any accounting" would have to include the carbon dioxide and any other greenhouse gases (methane, nitrogen oxide, ozone and so on) released in the production process, such as the considerable carbon released by clearing forests or draining peatlands. They would also have to think about the fossil fuels consumed in preparing the land and growing the biofuel crops, then processing and distributing the biofuel itself.

More than a quarter of Indonesia's palm oil concessions are said to occur on peatlands. The greenhouse gas emissions associated with such developments are vast. One ton of biodiesel from palm oil grown on peat is likely to generate more than 10 tons of carbon dioxide possibly much more - as well as significant quantities of methane, a very potent greenhouse gas.

In contrast, biodiesel from palm oil grown on some of Indonesia's already degraded lands would likely be much less greenhouse-costly and might also offer some environmental and social benefits. These details are of importance too.

The debate on biofuels must not be limited to simply the greenhouse effect and tons of carbon. Thorough research and understanding is required to avoid compounding past mistakes.

DOUGLAS SHEIL Center for International Forestry Research Bogor, West Java