A couple of weeks ago I went to visit one of the few emerging biogas plants in the country.
At Biogen (www.biogen.co.uk), near Bedford, they take in 30,000 tonnes of food waste and put it in large anaerobic digestors (ADs). Actually, they have to remove the packaging first, but the principle is pretty simple.
The digestors are really silos designed to speed up the rotting process and collect the methane that’s released. The brilliant thing about it is that all the gas can than be used for electricity generation – or even for vehicle fuel..
Good composting doesn’t just mean throwing your food waste into a composting bin and forgetting about it, which is pretty well what I do. It’s actually quite important to get a reasonable mix of wet and dry material and even to turn it over on occasions. Getting it right, not only means that it will produce lovely, rich organic matter to put on your garden but will also reduce your carbon footprint.
It’s not just the CO2 being released into the atmosphere but methane too – which is about 24 times worse in terms of its global warming impact. Most of the food we throw away in this country ends up in landfill sites, where methane emissions are a real problem. Not so long ago all these gases were allowed to waft up into the atmosphere or were simply burnt off with flares to stop explosions.
Nowadays, most dumps will be scattered with gas collectors that siphon off some of the methane and use it to make electricity. But this isn’t a very efficient process, which is why there’s strict European legislation aimed at reducing the amount of biodegradable waste going to landfill – and hence the amount of gas from rotting waste that adds to the blanket of greenhouse gases warming our planet.
A couple of weeks ago I went to visit one of the few emerging biogas plants in the country. At Biogen (www.biogen.co.uk), near Bedford, they take in 30,000 tonnes of food waste and put it in large anaerobic digestors (ADs). Actually, they have to remove the packaging first, but the principle is pretty simple. The digestors are really silos designed to speed up the rotting process and collect the methane that’s released.
The brilliant thing about it is that all the gas can than be used for electricity generation – or even for vehicle fuel. And what’s left behind is a great fertiliser – so almost nothing is actually wasted.
I was shown around the plant by Dan Poulson who’s been recruited by the founder Andrew Needham to help him expand the business. Expansion should certainly be encouraged. Dan and I worked out – back of an envelope type calculations – that if half the food waste in this country went to AD instead of landfill it would save the equivalent of nearly 10 million tonnes of CO, which amounts to the greenhouse gas emissions of around 1 million people (900,000 to be more precise).
The family interest in AD, at the Bedford farm, started from pigs. They have 23,000 which produce about 12,500 tonnes of potent slurry. Thinking about what to do with this led them to explore the potential of biogas. But it didn’t initially look like an attractive option because the payback period on investment was a couple of decades. That’s what made them think about taking in food waste too.
There are still very few councils who are collecting separated food waste – and those that do generally compost it. That’s better than chucking it in with all the other stuff we throw away but not nearly as good as an AD system. Biogen are already working with Luton, Mid Bedforshire and Ealing councils but don’t plan to stop there.
Given the benefits, it seems completely crazy that this idea has taken such a long time to be taken seriously. Over the next few years there’s likely to be an explosion (no pun intended) of interest in biogas. We should be encouraging it as much as we can – and certainly not complaining when asked to separate our food waste.
As for me, I’ve got to improve my composting techniques because a local AD system in South Somerset is not yet on the cards. But I hope the local council will get a move on and that they won’t be on their own.
Full article originally published on Telegraph online..
