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June 22, 2010

Biomass, which includes plant waste, wood, and other organic material, is considered a model green fuel because of its low-carbon properties. But what potential does it really hold in generating clean energy?

A farmer on a tractor in India
An Indian farmer with a load of harvest waste to be converted into bioenergyImage: atmosfair/kptl

In the northern Indian state of Uttarakhand, environmentally-friendly fuel is literally strewn all over the roads in the form of pine needles. The state has a mild climate, ideally suited for pine trees. The trees shed their needles once a year, carpeting the ground with the perfect material for making briquettes of fuel.

The use of biomass such as the pine needles in India is one way of generating green energy. The method reduces the use of fossil-based fuels such as coal and lowers greenhouse gas emissions.

Valuable waste

Biomass includes food crops such as canola and corn, but also wood, plant waste, straw and other organic material. They're used to generate electricity in waste incineration plants.

A canola field
Canola is a common fuel crop which often competes with grain for food productionImage: Jürgen Uting

Biomass is typically described as "carbon neutral." Proponents say it's a simple and proved renewable technology based on natural cycles.

The scientific principle behind biomass is the carbon cycle. As they grow, plants absorb carbon dioxide. The carbon builds tissues and feeds the plant while the oxygen is released. When plant material is burnt the carbon recombines with oxygen. The resulting carbon dioxide is released back into the atmosphere. The contribution of biomass to the greenhouse effect is therefore far less than for traditional fossil fuels.

Thus whether the pine needles in Uttarakhand decompose naturally or are burned - the carbon emissions are the same.

That's not the case with oil and coal. These fossil-based fuels and the carbon they contain are stored for millions of years under the ground. Burning such conventional fuel releases carbon emissions that interfere with the natural carbon cycle, damaging the climate.

Another advantage of biomass is that it's a renewable source. It's available in regular intervals - during harvests - as an energy source.

Biomass has limited potential

But several experts have pointed out that the potential of biomass to generate energy is limited. Daniela Thraen, who heads the bioenergy systems research area at the German Biomass Research Center (DBFZ) in Leipzig, said that biomass can at the most meet 10 to 15 percent of the world's energy needs.

According to Thraen, who is also the spokeswoman for the bioenergy department of the Helmholtz Center for Environment Research in Leipzig, there's a high potential for biomass in Eastern Europe, South America and Australia, and to an extent in North America. That's because these places have enough land and relatively small populations, she said, adding that fuel crops for biomass production would not compete with food harvests for scarce farmland.

Brick kiln workers gather biomass briquettes
The use of biomass fuels has made life easier for workers in a brick kiln in North IndiaImage: Christoph Kober

Densely populated regions such as Southeast Asia, on the other hand ,aren't ideal for biomass production, according to Thraen. While Africa isn't as densely populated and has plenty of arable land suited for biomass fuel crops or crops grown specially for use as environmentally friendly fuels, the continent's agricultural production is too weak, the expert pointed out.

She added that she didn't see any potential for biomass production in Africa that wouldn't compete with food crop production. And biomass energy production remains controversial because of concerns it could divert agricultural production away from food crops in poor countries.

The "food versus fuel" debate escalated in Germany in 2007. At the time, the rising global demand for fuel crops sent prices for wheat, corn and rice skyrocketing and food became hugely expensive in poor nations.

That fueled a public controversy over whether it makes sense to convert edible grain which should be feeding hungry humans into bio-fuels in order to power cars.

Readily available green energy

Thraen said that one particular advantage enjoyed by biomass is that it stores energy which - as opposed to sun and wind - is always available when it's needed.

"The potential for bioenergy thus probably lies in complementing wind and solar energy," Thraen said. "If the wind isn't blowing, you can offset it with bioenergy."

Thraen added that in future biomass could take the place of fossil-based fuels such as kerosene that can't be replaced by other renewable energies.

Clean and green waste

Bernd Bilitewski, head of the Institute for Waste Management at the Technical University Dresden said that biomass holds huge potential in other areas too.

He pointed that in Germany for instance, 12 million tons of unused organic waste is partially disposed off even though it's ideal for generating bioenergy. "These waste products must be used before we begin to work on other competitive products."

A close-up of hands that hold wood remains
Wood remains are used as briquettes or pellets to generate energyImage: BMU / Bernd Müller

He added that there was plenty of agricultural land that couldn't be used for food and animal feed production but was perfectly suited for the cultivation of fuel crops. That includes land previously used for mining as well as areas polluted by industries, he said.

Bilitewski said that Germany today hardly had a waste incineration plant that didn't use the energy generated through waste. But he added that bioenergy sources could still be used in a much more efficient way.

Concerns regarding waste burning center on the alleged poisonous gases released during the process. But Bilitewski rejected the concerns, saying that regulations and controls for waste burning were much too stringent and the technology was so sophisticated that it ruled out any poisonous residue being released into the air.

The waste management sector, he said, is considered one of the biggest contributors in Germany to lowering carbon dioxide emissions. According to him, around a fifth of the carbon cuts that Germany is committed to achieving under the Kyoto Protocol by 2012 comes from the waste management sector alone.

Author: Martin Schrader (sp)
Editor: Mark Mattox

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