Australia’s ‘dirtiest’ power station considers ‘clean energy’ biomass burning option

Drax currently consumes more than 3 million tonnes of wood pellets each year. Mr Brack says 5 million tonnes of carbon emissions are generated by burning those pellets, and they’re currently ‘missing’ on global accounts.

He says it’s partly because biomass emissions are treated differently to other carbon emissions. He says the problem is not currently being dealt with because it’s so complex, and also because so many other issues on the table as the world negotiates a new post-2020 global climate treaty.

In America, 46 US senators recently wrote to the US Environmental Protection Agency supporting biomass energy. The senators say that the ‘carbon neutrality of energy from forest biomass … has been repeatedly recognised around the world’.

But that’s under challenge.

William Schlesinger, president of the Cary Institute of Ecosystem Studies in Millbrook, New York, says: ‘In the US right now there are about four or five analyses that all conclude that if you look at the 20 to 50 year time horizon … that burning woody biomass is actually not helpful to mitigating climate change. It actually releases more carbon dioxide into the atmosphere than if you continue with coal.’

He says burning old or slow growing forests creates a ‘carbon debt’ that takes too long to pay back.

‘When you cut down a forest and burn it, you release all the historical carbon that forest has accumulated for many years,’ he says.

‘You release that all that once into the atmosphere. At the end of that day the forest no longer exists. It contains no carbon. All the carbon is in the atmosphere. It takes multiple decades for the regrowth of that forest to re-accumulate the carbon dioxide from the atmosphere. If you’re concerned about carbon dioxide emissions over the next 10, 30 or 50 years as a determinant of climate change, that’s a really unacceptable form of energy.’

Last year, Dr Schlesinger organised nearly 100 scientists to sign a very different letter to the US EPA.  The letter called for stricter guidelines on the use of biomass for power generation.

Dr Schlesinger says there are lessons for Australia.

‘I think Australia ought to look very carefully at how long it takes for the forest that are being harvested to supply biomass energy for power plants, how long it takes those forests to re-accumulate the carbon that’s being released with a single harvested burning,’ he says.

‘If it’s more than 20 to 30 years, one should seriously question whether that’s helpful to climate change treaty negotiations and protocols.’

So far, the US biomass industry has largely been export focused, driven by demand from power stations in Europe and the UK for wood pellets.

But like in Australia, the clean energy rules are changing and Dr Schlesinger says US power utilities are ready to move on biomass.

‘Right now the US doesn’t have any government mandated rewards for switching to biomass. But I think a number of the electric utilities see that on the horizon. They’re trying to get out in front of the game, essentially,’ he says.

‘Certainly in the south-eastern United States, there’s a number of the electric utilities there that have retrofitted some of their power plants so that they can burn both wood or coal. I think as President Obama’s Clean Power Act becomes enforced‚Äîwhich will give mandates to the individual states to cut their carbon dioxide emissions‚Äîthat the interest in biomass will explode.’

In addition to the argument over the climate credentials of forest biomass, green groups in the US accused one of the major US wood pellet exporters, Enviva, of environmental vandalism.

Enviva says that the company uses timber which doesn’t otherwise have a value or a market, such as old plantations established for the pulpwood market. Enviva did not respond to several requests from the ABC for an interview.

Dr Mary Booth, director of the Partnership for Policy Integrity says: ‘The Dogwood Alliance is a group in the United States that has been doing some fantastic work, actually tracking these logging trucks back and forth between the areas that are being cut and to the plant. They’ve documented with photographic evidence that (Enviva is) harvesting huge, huge trees from lowland swamp forests, really beautiful old trees that are being cut down and pelletised.’

‘These trees are … performing a vital function. When you cut them and you burn them, no matter whether they’re merchantable or unmerchantable, you’re taking forest carbon where it’s locked up safely and you’re turning it into atmospheric carbon.’

There are parallels of the international debate about the carbon neutrality of biomass burning in Australia.

Professor David Lindenmayer, from the Australian National University’s Fenner School of Environment and Society, is well known for his opposition to native forest logging. He says that the 100-year carbon time frame that United Nations organisations and national governments are working on is flawed.

‘When we look at what happens to carbon when it’s burnt‚Äîwhether it’s coal or a tree or what have you‚Äîour analysis shows that about 60 per cent of the carbon emissions fraction is reabsorbed back into the earth system after 100 years. But the remaining 40 per cent stays in the atmosphere for another 2,000 years. So there is no way that emitting carbon through emissions this way can be regarded as renewable energy. It just simply can’t. 

‘It’s a long-term carbon emission that has long-term impacts on Australia’s climate and on the world’s climate,’ says Professor Lindenmayer.

In Australia, the CSIRO and researcher Fabiano Ximenes from the NSW Department of Primary Industries have been trying to calculate the carbon life cycle of a logged forest.

‘What we’ve found is that a lot of the times the published research tends to overlook a lot of the essential components of the carbon cycling forest products. So they do a very good job of looking at the forest carbon side of things but I think they are quite a few omissions when it comes to tracking the fate of carbon in wood products, and that’s where I think there’s a big point of contention.

‘The latest work that we’ve been doing suggests that if you do take those things into account, if you look at the carbon storage in wood, if you look at product substitution impacts, and if you look at the fossil fuel displacement impacts of using biomass or bio-energy, when you combine those things with the carbon that’s actually stored in the forest in a production scenario, then you see that after multiple rotations you get a better … a more beneficial greenhouse outcome than if you are measuring a forest for conservation purposes only.’

Image: A handful of wood pellets, similar to those needed to fuel co-firing power plants. (Andrew_Writer/Flickr.com CC BY 2.0)

In Australia, biomass from sewage digesters and landfill gas already generate around 200 MW of electricity‚Äîabout one-fifth of a medium sized coal fired power station. Sugar cane mills also generate smaller amounts of power by burning bagasse, the waste from sugar cane.

Tasmanian resources minister Paul Harriss said recently he wanted to see a wood pellet plant and biomass plants established in the state.

‘Across Europe and the world, biomass is widely accepted as carbon-neutral and considered environmentally green energy. In Bavaria, there are over 700 small biomass plants dotted around the country,’ he says.

‘Now that’s with a forest industry about the size of Tasmania’s, yet here in Tasmania we have very few biomass plants.’

Stephen Schuck, from Bioenergy Australia, says Tasmania generated the only renewable energy credit from native forest biomass before the practice was banned in 2011‚Äîa decision recently reversed by the Abbott Government.

‘It was generated in the Huon Valley at an isolated power supply … My understanding is that renewable energy certificate costs an awful lot of money‚Äîover half a million dollars‚Äîto set up a dual-fired gasifier into a diesel generator. It was more to prove the concept that native forest biomass could be used. That half a million dollars cost was for a $50 or $60 certificate … developing the technology and installing the technology around it, and getting their bearings with how gasifiers worked.’

Dr Schuck says biomass for co-firing trials with coal has also been done by major electricity generators, for example Delta Energy in NSW.

‘A few years ago, Delta announced that that were heading towards a larger project which would involve a getting farmer groups to grow oil mallee eucalypts in central New South Wales, to coppice the biomass and produce wood pellets,’ he says.

‘They wanted to introduce these pellets in higher percentages with coal for co-firing. Their eventual target was somewhere around about 20 per cent ,which would convert a 500 megawatt unit at a power station to a 100 megawatt renewable energy plant.’

With no price on carbon and Renewable Energy Certificate prices falling, Dr Schuck says the project was put on hold.

‘The actual technology is probably the easy bit,’ Dr Schuck says. ‘The fuel procurement side‚Äîbasically procuring long-term supplies of biomass at the right quality and quantities‚Äîis probably the more problematic area.’

Australia’s biggest biomass project, at Albany in Western Australia, has solved this problem by sourcing its feedstock from eucalypt hardwood plantations that were originally established under the troubled Managed Investment Schemes.

Plantation Energy, which badges itself as Australia’s largest manufacturer of clean and renewable energy, uses only plantation stock, thus avoiding the debate about the best use of native forests.

Founding director Gavin Harper says markets are opening up in Japan and Korea for sustainably produced wood pellets for biomass power plants.

He says the company is named Plantation Energy for a reason. ‘It’s really important for internationally traded carbon credit certificates, whatever they’re called in different parts of the world, (they) really have to be supported by a certified sustainable management process which is very strictly controlled.  That comes down to not just the way the trees are planted, but what kind of land they’re planted on, so you’re not displacing food production.’

Mr Harper says Plantation Energy has also been speaking with Australian electricity generators about using the plantation pellets locally. ‘We’ve had dialogue with generators here in the west for a number of years, there is a lot of interest, it hasn’t happened yet, the numbers aren’t quite there, there is certainly some co-firing happening in the eastern states. I think that will be a trend that grows.’