Go Coal. Wood-fired electricity produces *more* CO2 for the next hundred years…
Any day now the giant tree-eating-machine called Drax will be shifting back to coal as Greens and politicians realize they’ve made a planet killing mistake. Lordy! At the moment, Drax is supposed to be saving the world and making electricity for the UK by burning trees cut down and shipped from the US.
This temple to carbon neutrality happens to be the largest plant in the UK . It generates about 7% of all the megawatts used there. But a new study by Sterman et al, suggests the Drax plan is backfiring badly.
When is carbon neutrality not neutral? When the carbon debt is not paid off in our lifetimes…
Burning forests instead of coal deposits raises CO2, and in so many ways:
- Wood is a less efficient fuel. Megawatt for megawatt, wood produces more CO2 than coal. In terms of efficiencies, the combustion efficiency of wood is 25% compared to coal at 35%.
- Processing losses to supply wood are around 27%, while losses to supply coal are 11%. (NEA 2011, IEA 2016, Roder 2015)
- This is the slow road to carbon neutrality. It takes 40 – 100 years to grow the trees.
- In a century, lots of things can go wrong. The natural forest may never grow back thanks to disease, development or fires. Cleared land may be converted to pasture. There are many ways to leave a permanent carbon debt.
- If the slow growing hardwood forest is replaced with fast growing pine, the site can only soak up 60% of the carbon “lost”. Oak-Hickory forest stores 211tC/ha compared to 131 tC/ha for pine plantations. A managed plantation can’t store as much carbon as an unmanaged one. After 500 million years of evolution, nature has fine-tuned carbon extraction in ecosystems. In an unmanaged forest, biology fills every carbon-sucking niche and doesn’t leave gaps for heavy machinery.
- If power-stations don’t use as much coal, the coal price may fall, and other people may use the same coal elsewhere anyway.
- The kicker: As long as biofuel use is expanding so are CO2 emissions. All biomass burning from an existing forest creates an immediate carbon debt. And if you are continually chopping down more forests, the carbon debts accrue…
The next pair of graphs shows that Shortleaf Lobilly (a pine) regrows quickly, while Oaks take 80 years to recoup the CO2 lost.
The real kicker
It’s all very well thinking about how long it takes one year’s wood-pellet electricity to become neutral, but power stations need more fuel every year and if we keep razing more land, the carbon debt keeps growing. In the two scenarios below the biomass industry keeps growing linearly every year. But in S8 people settle down on the whole biomass idea and stop razing extra forest in 2050. Even so, the total industry carbon debt keeps accruing for another 56 years until presumably the regrowth reaches a point where it is pulling in more carbon that the yearly raze produces. It takes 144 years after the industry stops expanding before the net carbon debt is back to zero.
What other industry today won’t produce a net benefit (its whole reason for being) for one and a half centuries?
If razing forests for electricity makes any sense at all (in the world of climate voodoo) it only begins to “help”, maybe, in 150 years or more. Would anyone let me buy carbon offset futures for 2168 and get a refund on the RET/carbon tax/electricity bills now? Who are we kidding?
If you believe that CO2 is a threat, then you’d have to also believe that biomass burning makes the next century even hotter than burning coal. Most greens will choose the biofuel. What’s more important – to be pro-climate or anti-coal? We all know the answer to that…
Even under a best case scenario burning wood is “not good” for the climate
The numbers are so clear here, every single pin needs to line up in the right way for forest to be useful as a fuel:
… using wood in electricity generation worsens climate change for decades or more even though many of our assumptions favor wood, including: wood displaces coal (the most carbon intensive fossil fuel); all harvested land is allowed to regrow as forest with no subsequent conversion to pasture, cropland, development or other uses; no subsequent harvest, fire or disease; no increase in coal demand resulting from lower prices induced by the decline in coal use for electric power; no increase in N2O from fertilization of managed plantations; and no increase in CO2 emissions or methanogenesis from disturbed land. Relaxing any of these assumptions worsens the climate impact of wood bioenergy.
It is quite difficult to imagine a way that burning forests for electricity could possibly make sense while the world has hundreds of years of coal underground and thousands of years of uranium and thorium. But if the aim is not to change the climate but to hurt independent companies that stand on their own two feet, then burning wood in power plants is just the thing.
The Australian Climate Sceptics gave the UK govt the Inaugural Gorebel Prize (for inconvenient outcomes) thanks to Drax
The winner of the Inaugural Gorbel Prize is the UK government whose green policies aim to make it uneconomic to burn coal. So the tax-payer funded Green Investment Bank has loaned £100 million to help convert the huge Drax coal-burning power station in Yorkshire to burning “sustainable biomass”. This is part of a huge finance package of one billion pounds to get the biomass green tick, earn renewable energy subsidies, and avoid the need to buy carbon credits.
Where do they plan to get the “sustainable biomass”? Each year 7.5 million tonnes of wood chips will be imported from North American forests to replace 4.5 Mt of coal.
How much land does it take to sustainably generate electricity?
This can only work if we start with a pine plantation or convert farmland (ho ho) into a pine plantation, wait twenty years, and use the wood solely for generation. But how much land will that take?
Other POSTS on BIOMASS
Sterman et al (2018) Does replacing coal with wood lower CO2 emissions? Dynamic life cycle analysis of wood bioenergy, Environ. Res. Lett. 13 (2018) 015007
US EIA 2016 International Energy Outlook (2016) (Washington, DC: US Energy Information Administration) p 276 (www.eia.gov/ outlooks/ieo/pdf/0484(2016).pdf)
Netherlands Enterprise Agency (2011) CO2-tool electricity gas and heat from biomass—version 1.0.1 (Assen, The Netherlands) (www.rvo.nl/file/1252)
Roder M, Whittaker C and Thornley P (2015) How certain are ¨ greenhouse gas reductions from bioenergy? Life cycle assessment and uncertainty analysis of wood pellet-to-electricity supply chains from forest residues Biomass Bioenergy 79 50–63
May 17, 2018 at 12:18PM