The Anaerobic Digestion Guide: A Sustainable Solution for Future Farming

Green initiatives are currently bombarding us, everywhere we look we’re being told how to shrink that carbon footprint, reduce emissions and work towards a cleaner tomorrow, with an increasing sense of urgency. The thing we’re not often told is, is it all actually working? Are our efforts really contributing and are these solutions really the be all and end all, the right path for an effective, greener future? With waste to landfill falling rapidly in recent years and recycling plants springing up left, right at centre, there’s definitely good news to be found in our efforts – so where could we improve? In 2008, farming and land use managed to output 48.4 million tonnes of carbon dioxide equivalent, making for 7.7% of the UK’s total Greenhouse Gas emissions. The modern day solution might well be anaerobic digestion.

How Anaerobic Digestion Works

The process of anaerobic digestion (AD) involves the breakdown of organic materials without the use of oxygen. Micro-organisms instead ‘digest’ this material and thus produce biogas. The plant and animal materials, often referred to as biomass, needing to be broken down are placed within a digester, a specifically constructed tank, and are left there whilst the micro-organisms complete the break up process.

The Products of AD

This then produces two elements – a methane gas referred to as biogas, and digestate, the remaining physical material. Biogas is often used as a renewable energy for generating heat and power, sometimes being used to power the digesters themselves making for a truly sustainable system, and even being converted into Compressed Natural Gas for use in CNG vehicles.  With up the physical solids being significantly reduced (often up to around 85%) the digestate left over is especially rich in nutrients and as such makes for an effective and ecological fertiliser, and in some situations it can be combined with other materials and composted or used to amend soils.

Future Farming?

Already AD is installed and functional in many farms across the UK and the world, but why would farmers invest in the technology? Whilst anaerobic digestion has a place in the food and waste industries, it lends itself naturally to farming by both the materials it produces and the significant impact it can have environmentally. The target has been set for the agricultural sector, with the Government expecting an 11% reduction in greenhouse gases by 2020, and it seems AD may actually be the answer, providing an attractive proposition on our farms due to the financial benefits that will give returns and help shrink running costs and energy bills. And when it comes to making a real environmental difference, AD ticks boxes as well providing:

• Methane – AD collects the extremely potent greenhouse gas that is methane and instead outputs a carbon neutral renewable energy.
• Nitrogen – From the digestate utilized as a fertilizer, the nitrogen is a comparatively more effective plant nutrient.
• Pollution – Feedstock can be reduced in  polluting strength by up to 40% via the use of AD, whilst polluting farm odour can be reducing by up to 80%.
• Pathogens – Salmonella is a pathogen that can often appear in feedstock –with AD this is significantly reduced overall.
• Weeds –  Weed seeds are killed in AD which means less chemicals will be required to tackle them.

Ultimately, farming needs to make some big changes in the coming years, and whilst many farmers are still on the fence about going ahead and investing in something as drastic as anaerobic digestion, its many direct financial benefits, plus the impact it will have on the overall environmental output of the farm make it a potential solution for sustainable farming for years to come.

This article was written by Rob Vicars of GTS Maintenance, experts in the field of anaerobic digestion and nitrogen purging. For more of their industry expertise, or to find out how their services can help, visit their website today!