Blog: Using slurry to power vehicles and reduce farm emissions

Thursday, 12 August 2021

Ben Williams, Senior Knowledge Transfer Manager, explains how ammonia from pig production could soon shift from being a major emissions problem to providing a solution.

Technology now exists to extract hydrogen from ammonia in slurry and use it to fuel vehicles.

Making this a widespread reality would be revolutionary for both farmers and society and help rewrite the story for livestock farming, which is continually under fire for its environmental impact.

If livestock agriculture can reduce some of its own ‘waste’ emissions and help offset the transport industry’s carbon emissions, then society can see how agriculture is not part of the problem but part of the solution. It’s a move towards net-zero emissions – and towards a more positive narrative around farming’s contribution.

The UK farming industry is already making substantial progress in reducing its ammonia outputs, but it will remain an ongoing concern, with 82% of UK ammonia emissions currently coming from agricultural production. The industry has a target to reduce ammonia emissions by 16% by 2030.

Pig producers have the chance to own the story and present consumers with some solutions. If we don’t act, the reality is that those consumers have the right to choose to walk away from pork and meat products.

Investigating the potential to produce green hydrogen fuel from livestock slurry is one of several projects AHDB is working on to help mitigate ammonia emissions from pig farming. It is a major opportunity for all classes of livestock production, not just pigs but dairy, beef and poultry as well.

Good fuel credentials

Ammonia is an amazing molecule, containing hydrogen in abundance. It is stable at low temperatures, combustible in its current state yet not so flammable it is dangerous. As a carrier for hydrogen, it has an energy density high enough to outweigh some of the concerns about how inefficient the hydrogen economy could be – and there is plenty of ammonia in agricultural wastes.

Companies such as Reaction Engines and Man Energy Solutions have shown that ammonia can replace a range of fuel sources, from jet fuel to heavy fuel oil, while New Holland has a hydrogen-powered tractor.

In short, producing ammonia from slurries can offset carbon emissions elsewhere while at the same time reducing the ammonia emissions from livestock. This is better for human health, better for environmental health and, importantly, a potentially profitable endeavour.

Changing the narrative

Figures are often used to suggest that livestock production is the most damaging industry on our planet, such as the FAO’s Livestock’s Long Shadow report saying that agriculture produces 14.5% of global emissions, with transport at 14%. There have been efforts to communicate the differences in how these figures were calculated, with a full life cycle assessment used for agriculture and the transport figure based simply on direct emissions. However, the bad publicity is already out there. When compared like-for-like, agriculture is responsible for just 5.3% of global direct greenhouse gas emissions compared to transport’s 14%.

The production of green ammonia either as a fuel itself or as a carrier for green hydrogen, therefore, has huge potential to change the narrative.

From a consumer’s point of view, knowing that their pork chops and the sausages grilled on their BBQ also produce the carbon-free fuel in their cars – which no longer have to be converted to hybrids or electric vehicles – would be a huge factor in their purchasing decision. It would allow pork producers and other livestock sectors to secure their ‘social licence’ to keep supplying the consumer.

There is, of course, a catch. One that organisations, including AHDB, will work towards supporting levy payers to overcome. To have a circular economy, whereby producers of food can become producers of fuel, there needs to be solid links with purchasers of fuel.


The logistics of distribution have been developing at pace, and companies such as Air Products have mobile fuelling stations that can enable disparate sites like farms to capitalise on their potential fuel sources. The water treatment sector faces the same issue of splitting solids from liquids and then capitalising on the value of these ‘wastes’.

Facilities already exist to use ammonia as a fuel to generate electricity going into the national grid. Ammonia is also stable enough and dense enough in energy to warrant being shipped in containers.

An energy revolution is needed. If the general public wants to drive an SUV, holiday on the Algarve and purchase avocados to go with their pork tacos, it presents an opportunity the pork sector is perfectly positioned to exploit – enabling people to continue their lifestyle in a carbon-neutral way.

Find out more about hydrogen electrolysis