Slurry cooling

What if we told you, cooling slurry in storage can reduce ammonia emissions by up to 75% and the heat extracted can be used to heat livestock housing? Find out how you can implement slurry cooling.

• Slurry cooling in storage can reduce ammonia emissions by up to 75%, helping to protect the environment and in-line with the 25 Year Environment Plan
• Your energy costs, and the use of gas and oil, can be reduced; energy extracted from slurry cooling can be used to heat livestock housing 
• Slurry cooling and slurry acidification both reduce ammonia emissions ‘at source’. This can lead to improved health and performance of the animals
• Reduced ammonia in barn atmosphere can benefit farm workers 
• Reduction in odour up to 15%

The UK has legally-binding, international targets to reduce emissions from 2005 levels by 8% by 2020, and by 16% by 2030.

Ammonia (NH₃) emitted from livestock manure is not only an odour concern; it is of environmental and human health concern. It also represents financial losses through increased fertiliser cost. Keeping ammonia in organic fertiliser (slurry), locks in nitrogen.

Ammonia in the atmosphere causes acidification of rain (acid rain) and can react with atmospheric sulphur dioxide to form fine particulates (PM10 and PM2.5) which are harmful to health. These particles eventually find their way into the human blood stream. In response to this, the UK government published the Clean Air Strategy in 2019.

• Low protein feeding of livestock
• Low emissions slurry spreading
• Covering slurry stores
• Low ammonia emission building types
• The Best Available Techniques (BAT) in pig farming is, in general, already being applied

There are several proven options available, such as storage covers, to help you reduce ammonia emissions and comply with forthcoming compliance targets for environmental permitting. 

Our slurry cooling guide helps you look for practical details on slurry-cooling technology. It covers how the technology works and how to install it. The key points are summarised below, along with a comparison of how cooling systems compare with slurry acidification.

Commercial units generally achieve a 30–50% reduction in ammonia emissions from buildings.

Cooling the slurry, in combination with a partly-slatted floor system, gives the best ammonia reduction, at 75%. The cooling circuit is usually installed in or on the floor of under-slat slurry storage.

The BAT document references Danish tests which have shown that ammonia volatilisation is reduced by 5–10% for every degree the slurry temperature is lowered (499, AgroTech 2008). The cooling effect is also influenced to some extent by flooring type, area and pen design.

Reusing the heat requires a heat pump that works on the same principle as refrigerators, making use of small temperature differences that transfer a small amount of heat energy from one place to another.

This is a Best Available Technique because it makes use of both ends of the process – first to reduce emissions by cooling slurry and then to heat water. It qualifies under the Government’s Renewable Heat Incentive (RHI) for quarterly payments over 20 years, based on the amount of heat generated.

Listen to our podcast with Ben Williams, our Knowledge Transfer Senior Manager, who speaks to three industry experts about some of the work that has been taking place to help farmers become more energy efficient as we move towards net zero.

Find out about the potential for releasing energy from slurry, the scope for improving energy efficiency on farm and how to make the most of renewable energy sources.

Featured guests: 

• Jon Foot, Head of Environment, AHDB
• Jon Swain, Senior Consultant, NFU Energy
• Martin Barker, National Pig Sales Manager, Duynie Feeds