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By Claus Felby
Bioenergy has become one of the hot topics in the
quest for new sources of renewable energy, and not
without reason. Every year plants on the surface
of the earth use their photosynthesis to convert
solar energy into biomass at an amount, which equals
more than five times the world’s current energy
consumption. If we can tap into this source of solar
energy and harvest say just 5% of the biomass, we
will be able to cover a substantial part of our
energy supply with renewable bioenergy such as heat,
power and transportation fuels.
Already approximately 10% of the world’s energy
consumption is covered by biomass, mainly wood used
for cooking in third world countries. But also in
the industrialized part of the world biomass is
increasingly used as energy source.
In the United States and many other countries bioethanol
as gasoline replacement has grown at an astonishing
rate, American output of maize based ethanol is
rising at 30% a year. Bioethanol is produced from
the conversion of starch from corn or sucrose from
sugar cane into ethanol by a relatively simple fermentation.
However, at the current growth rate, within a few
years the ethanol industry will begin to experience
problems of feedstock shortage. In order for 25%
of the nations transportation fuel supply covered
by biofuels, a current target, a new technology
which can convert cellulose the most abundant source
of sugar into ethanol must be developed.
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Courtesy
of Vestas A/S
One of the many types of biofuels, ethanol is
typically made from corn or sugar cane and is
mixed for gasoline engines. |
In the United States large research programs have
been launched to establish cellulosic bioethanol
with a clear aim of putting a commercial process
into operation by 2012. Also other bioenergy types
such as waste to heat and power and biogas are being
developed as potential sources of energy.
It may be worth looking to our allies on the other
side of the ocean, as on the shelf solutions to
some of the technologies may already be available
in Denmark.
Already 20 % of Denmark’s heat and power supply
is from biomass. The bioenergy is in the form of
co- firing of coal and biomass at central power
plants or conversion of manure and household waste
to biogas which is used for electricity generation
or for gas-driven buses and trucks. The Danish companies
BioScan and Niras are both ready with turn key biogas
plants, which can be adapted to a wide range of
biomass sources ranging from manure to household
waste and distillers grain.
Recently the world’s largest pilot plant for
cellulosic bioethanol has been build and operated
by Elsam Biosystems an affiliate to the largest
Danish power company DONG Energy. They have developed
what appears to be a very promising simple and reliable
technology, which can bring cellulosic ethanol just
a few years away from full scale commercial operations.
An important lesson to be learned form Denmark
is that by integration of bioenergy for heat and
power, bioethanol and biogas, not only can the economy
be improved, but also the energy balances are much
more favorable contributing substantially to the
energy output from biomass.
On an annual basis, more than 3 million tons of
biomass is used for combined heat and power production
in the Danish energy sector. The main sources are
straw, wood and household waste. A key part of the
supply is based on contract delivery with the farmers.
Experience shows that the system logistic setup
works well and can secure a stable year round energy
supply.
Like other countries Denmark confronts the challenge
of a balanced biomass supply, if the full potential
of bioenergy is to be realized. Not only security
of biomass supply for energy must be fulfilled,
but also the supply of food and feed crops must
be maintained. This requires a close cooperation
between the energy and agricultural-sector.
If current agricultural practice is maintained,
it will be difficult to keep the balance between
biomass for food, feed and energy. Fortunately such
tolls as breeding, inter cropping, and proper eco-system
management can bring us a long way towards a sustainable
biomass supply.
The future prospects for bioenergy are bright,
but require that the biomass supply is well structured
and planned; otherwise imbalances between food,
feed and energy will limit bioenergy to a small
niche. But for now the bioenergy leaders are full
of optimism, and believe that they can overcome
the challenges ahead.
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DENMARK
