The carbon-neutrality and renewability of biomass come under fire

“Biomass is a clean, renewable energy source.  If trees and crops are sustainably farmed, they can offset carbon emissions when they absorb carbon dioxide through respiration,” (1) says a recent article in National Geographic.  Sentiments such as these have altered the energy landscape.  In Europe, where politicians boast of its leadership in wind and solar power, biomass now covers close to half of the EU’s renewable energy consumption.  And by biomass, of course I’m referring to wood, although the former resonates better with most readers.

Many environmentalists and utilities love wood for various reasons.  Greens point to the much touted carbon-neutrality of biomass, claiming that new growth forests can simply reabsorb the carbon released by burning wood.  Power companies love the fact that wood can be burned alongside coal in a process called co-firing.  Due to co-firing, many coal plants will remain open as Europe tries to conform to stricter renewable energy requirements.  By 2020 the EU plans to meet 20% of its energy consumption through renewable resources.  Without wood, it would fall way short of its target.  Moreover, biomass provides steady, base-load power, whereas wind and solar remain intermittent. 

The proponents of biomass have won huge monetary gains.  Subsidies in the EU have soared.  Drax, one of Europe’s largest coal-fired power stations, plans to convert three of its six boilers to burn wood, and will receive a subsidy worth $68 per megawatt hour paid on top of the market price for electricity (2).  This will allow Drax to almost triple is pre-tax profit from 2012.  It’s not hard to see why utilities champion wood.   

Demand for the stuff has grown exponentially.  Imports of wood pellets into the EU rose by 50% in 2010 alone and global trade in them could rise five- or sixfold from 10m-12m tonnes a year to 60m tonnes by 2020 (3).  As firms and governments comb the planet for more trees to chop down, people have begun to question whether biomass deserves the label “renewable.”  It seems silly to think that forests will grow as quickly as we intend to remove them. 

The carbon-neutrality of biomass has also come under intense scrutiny.  Tim Searchinger of Princeton University calculates that “if whole trees are used to produce energy, as they sometimes are, they increase carbon emissions compared with coal (the dirtiest fuel) by 79% over 20 years and 49% over 40 years.” (4).  Additionally, the extraction and transportation of biomass requires the use of fossil fuels, so carbon is not just released at the power stations, but also at several points along the supply-chain. 

The EU’s desire to increase its share of renewable energy resources is noble, but the practical application of its policy has been quite the opposite.  Biomass subsidies prolong the use of coal, deter investment in wind and solar farms, and create and ever-increasing incentive to harvest more forests.  In the end, the use of wood in power generation may elevate carbon emissions, rendering biomass the most un-renewable of all our renewable resources. 






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