The Trouble with Biomass

Biomass is the term used for burning vegetation (mainly cropped trees) for the production of electrical energy and heat. Although not exactly the poster boy of Renewable energy, Biomass is actually the largest contributor to renewable energy generation worldwide.

Here is the energy share from Germany for 2014. ( from

Notice that the largest contributor to Germany's renewable energy mix comes from biomass.

In the UK it is no different. Even old coal plant like DRAX is turning to burning imported wood pellets from Virginia to replace coal because it is “Green” (and also attracts massive government subsidy)

But how “Green” is Biomass? How much CO2 (and other pollutants) does it mitigate?

How much does it reduce pollution from the dominant , ugly and disgracefully growing German addiction to Coal? In the UK - how much does it actually reduce CO2 (and pollution) output from DRAX?

An alarming report from the RSPB (Royal Society for the Protection of Birds) calls the whole Biomass methodology into question ( See Here ) This is explored further by this article (plus references on the CO2 Science Website in this Article Here

First lets look at the model that biomass implements. Biomass is a mostly a euphemism for burning wood.

The idea is that a forest plantation is cut down and burnt to generate power and/or heat. Of course this generates CO2 and pollutants, but if the forest is re-planted then it should, over a number of years lock down the CO2 as the forest grows.

Then when the forest reaches a certain maturity and so stops absorbing CO2, it can be cut down again and the whole cycle repeats. Do this over a sufficiently large forested area and you end up with a CO2 neutral energy generation.


Unfortunately the main underlying foundations of this model look increasingly wrong with disastrous consequences.

The trouble with the Biomass model is two-fold.

First it assumes that a forest stops being a net absorber of CO2 when it reaches maturity.

In fact a mature forest continues to lock down CO2 in leaf litter (that turns to peat) Dead standing and fallen trees take very many years to decay as they are naturally replaced. In fact the CO2 lock down from a mature forest is significantly more than that from a mere 20 year old plantation that has ironically been deemed mature enough to be cropped for energy production.

Secondly: The whole forest maturity thing is just plain wrong.

The Biomass concept of a mature forest or plantation is dictated by an illusionary time scale. It has nothing to do with the reality of Carbon lock down. The twenty year maturity figure on which the cropping cycle is typically based is out by a factor of five (at least)

The net result from these two problems is that relatively little carbon gets sequestered down by newly planted forest. Meanwhile thousands of Hectares of mature forest is destroyed for a momentary gain.

Renewable Energy may be fashionable. But its Biomass bedrock is in fact little better than Amazonian Slash and Burn.

So how bad is it really?

From the above RSPB report, generating energy from biomass is considerably worse than even burning even Lignite.

The cyclic burning of 20 year old Conifers generates 180% CO2 of burning hard coal or about 172% CO2 of burning lignite (not shown on graph) 

It is difficult to express how awful this is.

The RSPB report indicates that if you want Biomass CO2 equality with coal you need to give the conifers plantations around a 100 year lifespan. So essentially just to stand still on emissions you need to increases the area of mono-culture forest by a factor of five.

This is terrible.

I must admit, cynical as I am of renewable energy, I never-ever thought biomass could ever be as bad as this.

Biomass has been revealed as a terrible counter-productive catastrophe driven by fashion and pseudo-science. It is making the situation worse not better.

From these figures we can estimate that Biomass (KWh for KWh) produces about 4 times the CO2 of fracked gas - the current Bette Noir of the Greens. Even if you adopted a 100 year cropping cycle Biomass would produce twice as much CO2 as gas.

Nuclear (the ultimate monster of Green nightmares) is at the very least an order of magnitude less polluting than biomass (yes – read that again)

In fact (and I NEVER thought I would say this!) Germany and UK would be more environmentally friendly, produce less CO2 and less other pollutants by burning coal rather than biomass.

Prove me wrong.

But more importantly prove these guys wrong - if you can.


Flaxen Saxon said...

I can't disagree and I've got a Masters degree in Ecology. The supposed 'green' alternatives only work because of government subsidies. Fossil fuels are a hard act to follow. As for locking down carbon and releasing it into the atmosphere- I suspect the so called problem is overstated. The carbon cycle will go on regardless of what the 'green loonies' profess. It would take a massive pertubation to cause an increase in C02 levels which would then have an impact on global weather systems. As I've stated before, the future lies with nuclear energy. I can see my old Ecology Professor shaking his head in frank dismay. Sorry Prof.

BilloTheWisp said...

Thanks for the comment.

I must admit I was rather shocked when I first read the RSPB report. I thought initially that they were perhaps over-stating their case. But the references from the RSPB report and the CO2 Science site look solid.

Very depressing.

To substitute biomass for coal makes no sense. To substitute biomass for gas/nuclear is simply insane.

I expect though it is much more fashionable.

Philip Sargent said...

The RSPB report was the first time this really hit the headlines in the UK. DECC then created a model and wrote a substantial and detailed report on about 30 scenarios of US woody biomass being used to generate electricity in the UK. This was published (report, model and data) last July:

BilloTheWisp said...

Thanks for the comment and link. After cruising through the link it appears the document that is the basis of the DECC calculator is on the DECC site at

Very interesting reading.

I have only partially been through it but it looks like the DECC model, to an extent, backs up the RSPB paper for established forests and even some existing plantations (depending on plantation cropping age). The main scenarios I have come across that the paper produces to show a CO2 benefit involve wood waste and dead trees that are otherwise scheduled to be burned at the roadside.

As to the current American pelletised wood imports to the UK the report states:
In all cases, the energy input required to produce the electricity from North American pellets is greater than electricity from fossil fuels and other
renewables (except the most energy-intensive PV systems) and nuclear.


I appreciate that there are some scenarios where burning biomass (i.e. rubbish - wood waste etc) is beneficial but it seems unlikely that the main production from cropped wood would be CO2 beneficial whether it comes from German or American forests.

Thanks again for the link. I'd be interested in your take on this.

Philip Sargent said...

Sorry, I am not a policy official and so cannot comment.

Note that the energy input number is nothing much to do with the carbon emissions for any one scenario.

More recent published studies you might find intersting include this (difficult) paper and this easier read

BilloTheWisp said...

Point taken about the energy input (read in haste - regret at leisure) I take this is really the energy input in the processing/transport of the wood into fuel. It will be a contributor to the overall emissions from the fuel but will be a small part of the total.

However, The BEAC paper does appear to do little to undermine the RSPB report. In fact it does add some weight to it in places. While there are scenarios where biomass is less polluting than coal (a bad comparator - gas or nuclear better) there are arguably more realistic scenarios that are considerably worse.

I find it difficult to find much comfort in Mackay & Stephenson's BEAC report. It may give quite a few different scenarios but it most certainly does not counter (or set out to counter - to be fair) the RSPB report.

Thanks though for the links - I have yet to explore the last two but I will within the next week or so.