Renewable energy is one of the hottest topics widely discussed in the media right now - the newest UK government pledging to transform carbon emissions and reach Net Zero by 2030 - with much debate around whether new zero-carbon goals are actually achievable in such a short space of time, and what could be done to reach such an ambitious deadline? 

Alongside all of this comes the question of what, of all energy resources available to us right now, could be considered renewable, sustainable, efficient and economical; used to move us further towards those zero-carbon goals? 

Is woody biomass really renewable?

We’ve written before on a handful of subjects around burning wood: ‘Wood burning stoves: more polluting than a Waste to Energy plant?’ and ‘Is biomass carbon neutral?’ , exploring its impact on the environment. But, what if we take the questions one step further and ask the very direct but seemingly controversial question: is woody biomass really renewable? 

Google this question and you’ll find multiple articles confirming that, indeed, biomass, woody biomass and burning wood is indeed considered to be a renewable energy source due to the fact that wood is organic and part of the carbon lifecycle. 

This, however true to some degree, does feel somewhat simplistic in view and doesn’t necessarily take into account the entire cycle of burning wood; from growing enough trees to satisfy demand, to the emissions released into the atmosphere when such material is burnt for energy. 

The reality is that, although wood is an organic energy source, burning wood produces a lot of carbon dioxide and - actually - burning wood is widely considered to produce more CO2 than burning gas & oil. 

The typical composition of woody biomass

Knowing this, looking deeper into the composition of woody biomass specifically, we see the following [typical] components: 

• Carbon
• Hydrogen
• Oxygen
• Nitrogen
• Sulphur
• Moisture
• Ash
• Chlorine 

All of which will be released into the atmosphere upon burning said biomass, making the smoke emitted from wood burning especially complex in its make up; this not including the over 100 hazardous chemicals found in wood smoke that are toxic and carcinogenic, meaning that the issues with wood burning are not simply contained to greenhouse gases, but extend to a myriad of environmental risks. 

But trees absorb CO2…!

Of course, where trees are part of the carbon lifecycle and wood is an organic material, there is an argument to suggest that, well, trees absorb carbon! So, additional carbon released into the atmosphere by burning wood will be absorbed by surviving trees. Alongside this, more trees can be planted in order to absorb or offset carbon emissions. 

And, whilst this is partly true, in reality, you’d need to plant at least 15 - and up to 83 - trees to offset 1 tonne of CO2 per year. 

Biomass plants in the UK

There are several wood-fired biomass plants in the UK, including one plant in North Yorkshire that provides 11% of the UK’s ‘renewable power’; enough electricity to power 5 million homes across the nation and, compared to burning coal, the biomass pellets this plant burns reduce 80% of carbon emissions. 

What makes this particular project interesting, however, is the fact that the plant utilises bioenergy with carbon capture and storage (BECCS) in order to capture and store the carbon emitted, rather than allowing it to be released into the atmosphere. 

A forward thinking solution to a known issue, this is a great way forward for wood-fired biomass plants and something that should be positively recognised. 

Is the term ‘renewable’ too vague? 

If burning wood is known to pollute the atmosphere with copious amounts of CO2 and other toxins, why is it - and woody biomass - considered to be renewable? 

Looking at definitions of renewables and renewable resources, we can determine the following as a truth: 

Renewable energy is energy derived from natural sources that can be replaced by natural ecological cycles or sound management practices.

Of which, wood can slot very nicely into this category. 

But, perhaps the term ‘renewable’ - or the definition of the term ‘renewable’ - is just a little too vague? And, perhaps, we need to focus more on the idea of ‘clean’ or ‘low-carbon’ energy going forward, especially in the midst of the new UK government’s ambitious Net Zero plans? 

In summary 

Whilst technically woody biomass may be widely considered to be a renewable energy source, burning any amount of wood releases a lot of carbon emissions into the atmosphere and can easily be seen as polluting or damaging to our environment - contributing to the problem, rather than the solution. 

Attached to CCUS technologies, however, wood-fired biomass plants can significantly reduce their carbon emissions whilst providing a valuable and powerful source of electricity to millions of homes across the UK. But, an airtight plan does need to be put into place regarding what can be done with carbon once it is captured in order to put it to meaningful use. 

Woody biomass is undoubtedly a controversial subject in many circles and, whilst it may be better for the environment than burning coal, still can have a negative impact. Perhaps, then, definitions of renewable energy are simply too vague and we need to move towards clearer terms in order to categorise energy and new energy resources? And, perhaps, we need to view woody biomass and wood-fired biomass plants as an adequate middle-ground between a polluted past and a clean(er) future?