Pig farm trial shows ammonia emissions drop

Results from a trial monitoring ammonia emissions from pig farms show a reduction in emissions across a range of systems, saving producers millions of pounds in environmental mitigation costs, according to AHDB.

The aim of the accelerated ammonia trial was to collate data to update standard emission factors, which are used to report emissions to air annually under Environmental Permitting Regulations (EPR).

Trial results are not yet publicly available, but they have been used by the Environment Agency (EA) to produce revised emissions factors. Announcement of these is understood to be imminent.

See also: Environmental pig permits: Everything you need to comply

Potential savings

The savings, estimated at £15.3 million, arise from works that would otherwise have been needed under EPR to maintain compliance using standard emission factors on the 200 farms in the UK that currently operate under EPR requirements.

Replacement finisher housing accounts for much of the estimate, along with treating or cooling slurry, adding air cleaning systems and manipulating diets.

Emissions levels

Pig producers must meet best available technique (BAT) associated emissions levels (AELs). If they cannot prove they are doing so, the producers must pay mitigation costs.

AHDB says the trial proves that UK pig housing is fully compliant with BAT AELs. It also allows for updates in regulating the sector through accurate annual pollution inventory reporting and future habitat risk assessments.

Zanita Markham, AHDB knowledge transfer manager, said: “[The trial] demonstrates compliance on all housing types, which is to the industry’s credit. It also sets a benchmark against which we can measure further reductions in emissions in the future.”

New emission factors

AHDB began establishing a monitoring protocol in 2017 and worked with farmers to monitor the different pig systems, housing about 16,000 pig places, for a full year in 2019-20.

The results of the trial provide eight new ammonia emission factors for a range of pig housing types: fully slatted and free farrowing houses, and fully slatted and straw-based dry sow yards, weaner and finisher accommodation.

Until this trial, the EA used emissions factors based on national atmospheric emissions inventory (NAEI) data. But not all these figures met the BAT AELs for pig housing. Natural England also uses the emissions factors as part of planning applications.

Harley Stoddart, AHDB senior environment scientist, said: “Through working with an excellent contractor and group of producers, as well as the EA and Defra, this project has demonstrated the benefits of collaboration by providing robust evidence of ammonia emissions from a wide range of modern pig production systems.”

Regulations controlling emissions

Environmental permitting regulations (EPRs) aim to reduce pollution from industrial activity by controlling emissions. Indoor pig-keepers with more than 2,000 finishing pig places (above 30kg), or 750 sow places (including served gilts), at a site are required to obtain a permit from the EA.

Permitted sites are required to adopt minimum standards and best available techniques (BATs) – management practices, housing systems and methods that minimise emissions and environmental impact.

All pig farms have a duty to decrease ammonia emissions by 16% by 2030. The cuts will be driven by improved slurry management via slurry store covers and treatment.