Over 20 years ago I had a meeting with Age Jongbloed of the Dutch Directorate for Agricultural Research. We talked about the total amount of energy that goes into pig farming, on things such as feed, electricity and heating. And how, in the summer when it’s warm, we have to take the heat out of the sty through ventilation… Only to use more energy again in the winter to keep the pigs warm. Jongbloed said: ‘If there was some way for us to collect and use the energy we consume on feeding them, virtually no further energy would be necessary for keeping pigs.’ He had a point. But back then, we didn’t know how to achieve that.
Now, thanks to the new manure fermentation system we’re developing in our flagship farm, we’ve found the answer. The solution came from our decision to start removing the manure daily. In my last blog I explained how, in our new sty, we are keeping the pigs’ toilet and living areas separate. Prior to that the pigs had a semi-closed floor, so they were actually living on top of their own mess. In the new set-up there is a closed floor, and the pigs go to the toilet in a specially designated area, which is emptied daily. This is better for both animal welfare and human health, for example because the odours can’t get back into the sty. It’s also very good for the environment because you’re preventing nuisance odour emissions, and you can use the manure to generate sustainable energy for the farm. The advantage of daily manure removal is that this ‘fresh’ manure contains lots of undigested nutrients which can be turned by bacteria into methane (CH4) or biogas. These substances are lost if you leave manure where it is, unused, for a few months. Previously we were able to obtain 10m of biogas from 1m3 of manure, but since we’ve switched to daily manure removal, this has risen to 50m3 of biogas.
Here’s how it works. The fresh manure goes into our new mono-digester, which turns the carbon chains, such as starches or sugars, into methane (CH4) or natural gas. Through cogeneration we can then convert this biogas, so that we can use it for electricity and heating.
It’s a great system which is perfectly in line with the KDV energy fund principles. A system that requires a fair investment to put in place, but ultimately pays for itself through energy savings for the pig farmer. If a farmer buys in electricity, it costs around 15 euro cents per kilowatt (including tax and other costs). But farmers with this manure fermentation system can avoid these costs altogether. Plus they’re no longer dependent on the electricity grid.
How far have we got?
We’re ready for this new system. We’re still going over the final financial risks with the government, then in May we’ll be able to start building the digester and the co-generator, which we’ll be able to install this summer. We’ll let you know how we’re getting on in these blogs.
Three advantages of a manure fermentation system with daily manure removal
- Animal welfare and animal health: the manure is not directly below the pigs, so odours and bacteria don’t come back into the sty.
- Human health: with immediate fermentation you ensure that all kinds of bacteria don’t come into contact with any antibiotics that may also be excreted by the animals. This means bacteria can’t mutate, which would encourage resistance development.
- Environment: with daily manure removal there are no nuisance odour emissions and you generate sustainable energy, so you don’t have to buy in fossil fuels (gas and electricity) for the farm.