Is clean energy from biomass a myth?

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The European Union has set a general aim to increase renewable energy production so that it accounts for 20 % of all energy production. This means wind, biomass, hydroelectric and solar-derived energy sources. There is very little unharnessed hydroelectric capacity left in Europe, and most of the remaining possibilities for dams and artificial lakes are in environmentally important areas. Flooding them to generate electricity is controversial and would undermine the efforts to preserve the scarce remaining natural environment.

Both wind and solar are available in parts of the region to an economically feasible extent, but both sources suffer from the fact that energy production is not even and continuous. Greater use of solar energy especially for low-energy purposes such as warm water production is to be encouraged, for example in the Mediterranean countries, but it is of much less value in the north. In these regions, the wind also tends to be weakest when the January temperatures are at their lowest.

The uncertainty and uneven production of other forms of renewable energy have increased the hopes of resorting to bioenergy to balance the equation. The question has to be asked – is it available in the quantities needed, and if it is, what would be its safety record?

There have been four major paths for utilising bioenergy. The simplest is to use wood for heating homes. The second one is to use biomass (wood, pellets, biological waste) in regional power plants, often in cogeneration of heat and electricity, the third is to produce ethanol from biological material to be used as a biofuel in motor vehicles, the fourth is to produce diesel or gasoline from forestry biomass or other sources of biomass.

Many environmentally thinking families have thought that heating their homes with wood logs would be more environmentally friendly than the other alternatives.[1] There are two problems in this approach. First, the efficiency of producing energy in a fireplace is poor, somewhere between 10 to 60%. The rest of energy goes up the chimney to be blown away by the wind. The percentage can be improved by sophisticated furnace technology and the use of wood pellets, and then it is possible to achieve 70–90%. The other problem is high fine particulate matter emissions.[2] In Finland, a country of forests, the percentage of fine particulates produced by local wood burning is as much as 25% of total emissions, while the percentage of energy produced is less than 5%. Fortunately much of the emissions are in the countryside and not in towns where they can represent a serious health risk. Clearly, wood burning in traditional fireplaces in the home is not something to be recommended in densely populated areas.

The second possibility of using wood, pellets or other biomass in well controlled regional power plants clearly has more in its favour. The efficiency of power plants co-generating electricity and heat may even exceed 90% with the best of conditions. At present, this is by far the most efficient method of using bioenergy. Furthermore, particulate emissions can be controlled much better than in other forms of using bioenergy.

Bioethanol created a series of unexpected consequences that should not have been so surprising at all. Whether produced from sugar cane or corn, bioethanol competes with food production. The question is: can we afford to reallocate food production capacity for energy production? Moreover the efficiency of the production is such that it is unlikely to be profitable without huge subsidies.

Setting administrative requirements for using a certain percentage of bioethanol in automobile fuels may be another example of how governments should not operate. Politicians and bureaucrats should set general aims, with the prime aim being to decrease carbon dioxide emissions. There are thousands of scientists and engineers in Europe who can then determine how best to decrease the emissions, and the chances are fairly slim that politicians and bureaucrats behind their desks in Brussels would think up a better technical solution than these scientists and engineers.

The fourth alternative to produce liquid fuels from solid organic material is not new. The Fischer-Tropsch synthesis was described in 1920s, and the Germans scaled it up to mass production level during the Second World War when oil imports were impossible but plenty of coal was available. In the long run, this is probably the most promising technology to produce liquid fuels for cars, unless advances in hydrogen and battery technology will make it obsolete.

The problem with all synthetic fuels is that some energy has to be used for production of the fuel. For example, this is very clear with bioethanol. Therefore, in principle, the less the fuel has to be processed, the better for the overall efficiency. Therefore at least for the time being, the best way of using bioenergy is to use it as a solid fuel in regional energy plants for cogeneration of heat and electricity at very high efficiency rates.

Bioenergy is not a magic wand which would solve all our energy problems. There are many health problems involved, and at present the efficiency of most forms is far from satisfactory. Some forms are feasible for use today, notably biomass used to cogenerate heat and electricity in well-planned power plants.

Notes and references

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