Archive / Magazine / Society / How green is biofuel? / Article | 24/09/2008

The dream of clean energy

A beginner's guide to biofuel: Where does it come from? How is it produced? What is its technical potential?

Whether the discussion is about environmental protection or about combatting climate change caused by greenhouse gases, increasingly the key issue is energy. Because the transport sector has the highest energy requirement, is almost completely dependent on oil and is also growing rapidly it is held responsible for the most alarming scenarios concerning the future of our planet.

Photo: AP

In response biofuels have been developed as an environmentally-friendly substitute for oil. But are they really the answer to all our problems?

From rapeseed to soya beans

Biofuels are liquids or gases produced from biomass that can be used to drive combustion engines. Particularly in the transport sector they can serve as a substitute for fossil fuels. Petrol can be replaced by ethanol obtained by fermenting saccharose (from beetroot or sugar cane) or starch (from wheat or maize). Various seeds containing oil like rapeseed or soya beans or the fruits of the oil palm can be used to produce a diesel subsitute. By means of a process known as transeterification – which involves a reaction with methanol – these oils are transformed into a compound that can be burned more efficiently.

Zero CO2 emissions

From a technical point of view biofuels work well. And the scarcer oil becomes the more economic they are. They are considered to be the energy of the future to replace diminishing oil and gas reserves. Moreover, they do not harm the environment: although like fossil fuels they emit CO2 when they are burned, the process of photosynthesis necessary for producing biomass absorbs the same amount of CO2 as is emitted during combustion, thus resulting in zero CO2 emissions.

Production problematic

On account of their real life cycle assessment, however, there is some controversy about whether increasing the use of biofuels would really bring benefits because the energy needed for growing biomass (agricultural machinery, fertiliser etc.) and for processing it must also be factored into the equation. For this reason net production is much lower than gross production. Net production per hectare for ethanol is good, but the concomitant agricultural and industrial processes require a lot of energy. The cultivation of rapeseed oil requires little energy, but gross production is low. The European average for net production is about one ton of oil per hectare. Under these circumstances about 20 percent of agricultural land would have to be set aside in order to replace a significant proportion (the EU's goal is 10 percent) of the fossil fuels currently used for transport with biofuel. This goal is, however, incompatible with the requirements of other agricultural production, particularly food production. In the European Union of twenty-five states about 5 percent of agricultural land was used to produce biofuels. Germany and France are still the main producers of biofuels.

Imports from tropical countries

The introduction of quotas requiring a certain amount of biofuel to be added to fossil fuels will inevitably mean that large amounts of ethanol derived from sugar cane and palm oil will need to be imported from tropical countries, above all Brazil and Southeast Asia. This would involve turning large areas of rain forest or savanna into arable land, which would in turn lead to the emission of large quantities of CO2. This is not compatible with the goals set for combatting climate change. The other major problem is that production of biofuels has to compete with food production, which is already scarcely able to meet rising world demand.

Energy use in the society of the future

There are three possible approaches for the future. The first would be to make radical changes in agricultural practice, trade routes and infrastructure in order to reduce the need for transport. Even though there is no doubt about the wisdom of this approach, it runs counter to current developments. Nevertheless, rising energy costs may eventually result in an automatic reduction in transport use. A second solution would be to promote alternative forms of transport: switching to public transport, electric cars, cars that use very little fuel, cycling and walking could lead to a swift reduction in the amounts of energy consumed. Finally, it is possible to produce biofuels from wood, straw and waste from the cellulose industry. A lot of research is currently being done in this area but it cannot be factored into the energy equation until it has been fully evaluated by scientists.

Paul Mathis

Paul Mathis, born in 1938, is an agronomist and holds a science doctorate. He has done research in the fields of bio-energy and photosynthesis. He ...
» to author index

Further articles on the subject » Environmental Policy, » Energy, » Agriculture, » Science / Research, » Europe, » Global
More from the press review on the subject » Environmental Policy, » Energy, » Agriculture, » Science / Research, » Europe, » Global