Biomass bummer: carbon mitigation could increase ozone

Trees make isoprene makes ozone

A team from Lancaster University has poured cold water on Europe’s increasing plan to increase the biomass it uses in electricity production, saying that that while non-fossil fuels can improve the carbon picture, it comes at the cost of air quality on the ground.

The problem, according to research led by professor Nick Hewitt, is that many of the forest crops that are favoured for biomass can increase ozone down at ground level.

In a study to be published Nature Climate Change, Hewitt’s team found that poplar, willow and eucalyptus trees – all fast-growing and relatively high-yield sources of biomass for conversion into fuel – emit high levels of isoprene while they’re growing.

Hewitt told Reuters that when it mixes with other pollutants in sunlight, isoprene forms ozone.

Ozone causes an estimated 22,000 deaths annually in Europe, the Reuters piece notes, and Hewitt believes a European plan to expand tree plantations under a plan to ramp up its biomass use could add another 1,400 deaths to the list.

He also fears that ozone from the plantations could reduce wheat and maize output “by $US1.5 billion since ozone impairs crop growth”.

He suggests that trees could be genetically engineered to reduce isoprene emissions, and states that plantations should be located away from urban pollution. ®

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