Рубрика:
63
land cleared. In terms of habitat loss and carbon debt, one of the worst offending
biofuels is palm oil. Biodiesel from palm oil is cheaper than from any other crop, and
palm oil export from Indonesia is set to be a major contributor to EU targets. But the
expansion of oil palm plantations, replacing mature rainforest, has been an ecological
disaster. Clearance often involves burning vegetation or draining peatlands,
increasing Indonesia’s CO2 emissions such that it is now the third highest globally.
Creating palm oil plantations destroys land with some of the highest biodiversity in
the world, and contributes to the loss of habitat of many animals including the
orangutan, which is threatened with extinction, as it loses habitat and is also killed as
a pest of the young oil palms. Like all monoculture, the plantations are vulnerable to
disease which can spread easily from plant to plant across the whole area. Palm oil is
not even particularly efficient to produce and use – grown on regular rainforest it has
a carbon debt of 86 years, and on peat forest this rises to a massive 423 years. By
increasing the market for biodiesel from palm oil, we are promoting all this
destruction just to fool ourselves that we’re making a difference to emissions.
Much research has been done and is ongoing to overcome these problems: avoiding
dependency on food crops, and increasing the efficiency of fuel production to reduce
the amount of land required. Second generation biofuels use biomass like straw,
grass, and woodchips and are based on the structural compounds cellulose and lignin
which are present in large amounts in plants compared with sugars and oils. This
contributes to their improved efficiency – for example, a 50% reduction in emissions
is achieved using ethanol produced from grasses grown on the American prairies
compared to 20% from corn. They can be produced from waste material, or crops like
Miscanthus that can be grown on marginal land, so they are likely to have a much
lower impact on food security and habitat loss. To generate liquid fuels, the long-
chain carbohydrates in the biomass must be made available for fermentation. This is
technically difficult and requires considerable energy inputs in itself, but research is
ongoing to make the process more efficient, such as investigating the processes which
allow termites to digest wood.
Perhaps one of the most exciting developments in liquid biofuels has been the use of
algae. The attractive thing about algae is that they are not food crops and they do not
have to grow on land that could be used for food crops. Algal culture in custom-built
open ponds or closed bioreactors could be sited on any land, including waste or
industrial sites, marginal land or desert. Another benefit is that algae have a much
higher growth rate than multi-cellular plants, making them “the most prolific energy
conversion systems on the planet”, and many species are able to produce long-chain
hydrocarbons which need minimal processing to be used as fuel; they produce and
excrete diesel. Certain varieties are also capable of producing hydrogen, which could
be used as a fuel.
So, while ongoing research could uncover important players in the future energy
mix, many of the currently available sources of biofuels do little to reduce emissions
and could actually exacerbate problems with food security and habitat loss already
caused by global warming – the very things that biofuels are trying to address. Both
governments and consumers need to become aware of the difference between ‘good’
and ‘bad’ biofuels, rather than just equating ‘biofuels’ with ‘green’. There is little
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