Thoughts for…

June 2017

Can Anaerobic Digestion play a significant role in the achievement of Paris Agreement targets?

Very recently the international effort to reduce greenhouse gas emissions has figured significantly in press coverage for, frankly, baffling reasons. The Paris Accord of December 2015 was playfully described by Francois Hollande as “the most beautiful and the most peaceful revolution” that Paris had ever experienced (ha ha!), and at the time he was right. But then Donald Trump was elected and made the staggering decision last month to withdraw the U.S. from the accord. So the second-biggest polluter in the world positioned themselves on the side lines while the rest of us do all the work.

Focus in the UK has been on the installation of solar panels and wind turbines in an effort to make our contribution to global targets. If you speak to most lenders (and I’ve spoken to a few) you will find that the vast majority of them have not lent to a business or an individual who is installing an anaerobic digestion (AD) plant, and have no policy around it. That is a real shame because the potential that AD has to reduce greenhouse gas emissions is quite something. An anaerobic digestion plant is roughly 90% efficient. A 100kW small-scale plant (which can generate the electricity needed for around 100 homes) produces as much electricity as a 300kW wind turbine or 900kW solar array per year. Most technologies are weather and condition dependent and efficient during their optimum times. Great. But AD plants work 24/7, 365 days a year, and are largely only dependent on their component parts. So who has the upper hand?

CO2 and reducing the carbon footprint is big business. It’s now the norm to refuse to buy certain products purely on the basis of the distance that they have travelled. And that’s all good. But did you know that methane, the smelly gas that we all produce and which cattle produce in shed-loads, is 20 times more harmful to the atmosphere than CO2? Yep, that’s right! So consider that AD is the only renewable technology that handles methane emissions and the conclusion is clear. Not only can it be a way of handling methane-rich waste (slurry) but add to that, generating energy through AD offsets the need for fossil-fuel generated energy, and using digestate as fertiliser offsets the need for petrochemical based fertilisers, and the place for AD as a component solution to the greenhouse gas emissions problem is clear.

So why isn’t AD a more widely recognised solution? AD is hugely popular in Germany, Sweden, India and China (for very different reasons, granted), and is not a new concept within the UK either, so that question can be a puzzler, until you realise that the answer is simply education and the absence, until now, of any need for an alternative. Essentially, most people don’t know what anaerobic digestion is or can’t overcome their initial misconceptions of it as a thoroughly unpleasant and smelly waste of time, and why would we need an alternative when we have our lovely, reliable fossil fuels? Overcome those two issues and then we have money to deal with.

There has been a huge leap forward in numbers of AD plants in the UK during the last 3 years from around 130 to 540, but this level of growth isn’t maintainable without further significant improvements in understanding, and consequently, funding. And that is the key. So the answer is that AD could make more of an impact that any other renewable technology, given the chance.


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