Organics AD infinitum

Charlie Flounders, Commercial Manager, Feedstocks at Tamar Energy gives us an update on how the organics/AD market is faring.


Few renewable energy technologies have seen the levels of growth achieved by anaerobic digestion (AD) over the past five years. As an industry, we calculate that AD could: deliver more than 10 per cent of the UK’s domestic gas demand; create 35,000 green jobs; contribute about £3 billion to the UK economy; and produce biofertiliser worth £200 million, in the process recycling essential nutrients. The AD sector has the potential to not only improve the UK’s energy security but also reduce the UK’s total greenhouse gas emissions by over two per cent. Few industries can make a significant contribution to so many national goals.

An eye on the markets: organics/AD

There are now over 150 AD plants treating organic waste in the UK (as opposed to sewage), up from 68 in 2011. Today the AD sector consists mainly of small-scale and on-farm plants (like the one pictured, right). There is an industry-wide generation capacity of 154 megawatts of renewable energy, while capacity for the treatment of food waste stands at approximately 2.3 million tonnes per annum. But there is significant potential for growth; the UK generates over 15 million tonnes of organic waste per year, six million tonnes of which is food waste from homes and businesses. 

In line with the waste hierarchy, waste reduction and reuse should come before recycling and energy recovery, and then the best place for food that is no longer safe to eat is an anaerobic digester or a composting site. There is legislative pressure too: the European Union’s Landfill Directive commits the UK to reducing organic waste to landfill to 35 per cent of its 1995 baseline by 2020 – a deadline that is fast approaching. 

This article was taken from Issue 81

But food waste recycling levels continue to lag behind other recyclables. The key to ensuring more food waste is used to generate renewable energy is segregation. Over 50 per cent of households still don’t receive dedicated food waste collections in England. Food waste is heavy, and, with landfill tax increasing to £82.60 per tonne in April 2015 and total gate fees for landfill at £100 or more, it’s expensive too. It is clear that the landfill tax incentive mechanism is not working as designed, and the AD sector will work to ensure the new government has the facts needed to rectify the existing system or implement a ban on organic waste to landfill. One interesting option could be a national roll-out of the Scottish regulations that already require food businesses producing more than 50 kilogrammes of food waste per week to recycle it.  

Transport costs are a factor if the waste has to travel excessive miles to a food-processing AD plant. We will see more AD plants rolling out close to the waste supply, and as AD infrastructure grows, source-separated collections could offer savings on gate fees alone of over 60 per cent.  

Some have argued that we may face an over-capacity of AD plants due to the number of projects in the planning process. Yet changes to the government’s energy tariff regime make the economics borderline for many small-scale projects, and deploying large-scale AD plants is a complex, capital-intensive, time-consuming process. Moreover, AD plants require 24/7 expertise to operate efficiently. Realistically, many projects will not be built.  

Looking ahead, we will see real development in the market for digestate – the valuable by-product of the AD process. Digestate with the PAS110 quality mark is a nutrient-rich biofertiliser and environmentally-friendly alternative to traditional petrochemical fertilisers. The market is in its infancy, and initial trials within the agricultural sector show very promising results.