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Big Wood

Construction will start soon on a giant wood-fueled power station in Wales. But where will all that wood come from? Where will the ash go? And why not use the waste heat?
By Simon Hadlington
Port Talbot on the coast of Wales, at the western edge of the United Kingdom, is probably not the first place that would spring to mind as the location for a remarkable experiment in renewable energy. The town, once the hub of the United Kingdom's thriving steel industry before recession hit hard in the 1970s and 1980s, has seen more industrially prosperous days.

But Port Talbot could become home to the world's largest power station run on biomass. A 350-megawatt plant-gargantuan by industry standards-is scheduled to move from the drawing board to the building site within the next few months. The plant will be fired by wood chip. The company behind the project is Prenergy Power Ltd., owned by Switzerland-registered Global Wood Holdings, which is partly owned by TMT Co. Ltd., the Taiwanese shipping group.

The Port Talbot plant, scheduled for commissioning in 2010, will produce 70 per cent of the renewable energy target for Wales by providing electricity for around 550,000 homes-half of the households in Wales. The cost of the plant is expected to be around $750 million.

Given that a typical wood chip power plant has a capacity of around 5 megawatts, and a 40-megawatt plant is considered to be large, the scale of Prenergy's ambition is enormous. "It is," says Peter Richards, business manager of Austrian biomass energy company Cycleenergy and an expert on the industry, "something like sending a man to the moon."

Crucial Location
The location of the proposed plant adjacent to a deep water port is crucial to the economics of the project. The plant will require 3 million tons of wood chips annually, which the company says will be imported from a number of countries in North America, South America and Europe. "All the sources will be independently certified as sustainable and we will have an audit trail confirming the source of each shipment of wood chip," Prenergy spokesman John Anderson told Biomass Magazine.

The company is investigating the best way to dispose of the estimated 80,000 tons of ash produced each year. The ash could be used as a soil conditioner or fertilizer for forestry or agriculture, used in the cement industry, or deposited in landfill. "Our preference is strongly for the first option and we are working with forestry experts to develop methods of conditioning the ash to produce the right characteristics to allow it to be easily spread," Anderson says.

Certain aspects of the project have, however, been criticized and some industry insiders remain curious to see how Prenergy will be able to source and transport the vast quantity of wood chips that it will require.

One issue that has been raised is that the plant will provide only electricity, and will not pipe excess heat to local businesses and homes, as combined heat and power plants do. In response, the company says that the infrastructure for supplying heat locally does not exist in the UK in the same way it does in parts of continental Europe. Furthermore, the company says, the plant is designed to generate electricity far more efficiently than smaller plants, with an efficiency of around 36 percent compared with typically 22 percent for small plants.

Concern has also been voiced about the use of shipping, which itself generates pollution, to transport the fuel. Prenergy insists, however, that for a project of this scale water transport represents the most environmentally benign form of transporting bulk quantities of raw material.

In principle, a wood-burning power station is a good idea, says Dan van der Horst, an expert in biomass energy at the University of Birmingham in the UK. "Biomass only reduces carbon dioxide emissions if the energy put into growing the biomass produces significantly fewer emissions that you displace by using biomass as an energy source," he says. "Generally for woody biomass from sustainably managed forestry this is not a problem-as it can be for other kinds of energy crop such as rapeseed, cereals or even short-rotation coppice such as willow or poplar, which require agricultural inputs."

He points out that while shipping the wood chip will produce pollution, the carbon emissions for shipping are often not taken into account when calculating the "carbon advantage" of a fuel source. "Because pollution caused by international shipping does not get ascribed to any single country, it tends to be ignored by people considering only national targets for reducing carbon emissions," says van der Horst.

Wasting Heat
Of far more concern to van der Horst is the fact that the new plant will not be using its excess heat. "My big concern with generating electricity from wood is that if you are simply lighting a big fire under a big boiler solely to produce electricity, you are losing 60 to 70 percent of useful energy through heat loss," he says. "One way of dealing with this is to use the heat to heat homes, but the energy markets in the UK tend not to favor this kind of approach and energy providers claim it is simply too expensive to install the necessary infrastructure. But if you do not use this heat you waste two-thirds of your biomass energy."

For van der Horst, the most efficient way to turn biomass into electricity is to burn it together with coal in coal-fired power stations. "This directly displaces coal, which is the most polluting fossil fuel," he argues. "A brand new biomass plant producing only electricity is a bad idea."

Cycleenergy's Richards, meanwhile, will be watching the progress of the new plant with fascination. "The project is particularly interesting because of its phenomenal size," he says. "If you consider that 200 megawatts of renewable energy through biomass is considered a typical target for a country trying to stimulate this form of energy generation, that is equivalent to 50 plants each of 4 megawatts capacity. So one single plant of 350 megawatts is unbelievable."

Transporting the fuel is clearly an issue, says Richards. "There was a case of a 50-megawatt wood-burning plant in Hungary, which required 14 truckloads of fuel a day," he notes. "For a plant of 350 megawatts bringing the fuel by land would be exorbitantly expensive, so it is quite clever putting it on a port. But nevertheless the sheer logistics remain interesting."

Håkan Ekström, an expert on the global wood trade at Wood Resources International in Seattle, points out some of the challenges that could face the new project. "If they need to import 3 million dry tons of wood fiber it sounds like a huge project," Ekström told Biomass Magazine. "The volume is slightly less than what the entire Swedish pulp industry is consuming in one year, or twice the chip volume the German pulp industry is consuming. Japan is, by far, the largest chip importer in the world and they import 13 million dry tons per year.

"So entering this market to purchase 3 million tons sounds like a difficult task, but it all depends on what they are willing to pay for the wood. And it is not going to be easy to find that volume of certified wood unless they plan to chip pulpwood and that would be really expensive."

Simon Hadlington is a journalist who covers biofuels from his base in York, United Kingdom.
 

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