Slurry Cooling

Exploring the benefits and reducing ammonia

What if we told you, cooling slurry in storage is reported to reduce ammonia emissions by up to 75% and the heat extracted can be used to heat livestock housing, thus reducing energy costs and the use of gas and oil?

There’s a number of proven options available to help you reduce ammonia emissions and comply with forthcoming compliance targets for environmental permitting. Slurry cooling and slurry acidification both reduce ammonia emissions ‘at source’ which, in turn, can lead to improved health and performance of the animals and reduced odour emissions. Storage covers are another option for compliance in reducing emissions.

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

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.

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

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.

What does the clean air strategy mean?

  • Low protein feeding of livestock
    • Already generally applied
  • Low emissions slurry spreading
  • Covering slurry stores
  • Low ammonia emission building types
    • Pigs already are generally applying Best Available Technique (BAT)

The technique involves cooling the surface of slurry in underfloor stores to 12°C or less (optimum of 10°C), by pumping cold water through a heat-exchange system.

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.

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.

Reusing the heat requires a heat pump which 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.

We recommend that you start with calculating the amount of heat needed, which can then be used to determine the scale of the cooling loop required to supply it.

Cooling systems bring most benefit when installed in a fully integrated unit, incorporating the full pig production cycle.

The low-density polyethylene pipes for the cooling and heating loops are cast in the concrete floors of new builds, with a spacing of 35–40 cm between pipes.

Note, cooling is not effective for large volumes of slurry, so it needs to be installed in housing systems where slurry is removed frequently.

Pipes are connected to a heat-exchanging device (pump or plate) to recover process energy, which might be used for heating other parts of the farm, particularly for farrowing and weaner accommodation.

The heat, in the form of hot water, is normally between 35–50°C. Moving heat in this form over any distance is expensive, which means that heat is better used close to the source.

Some European installers anticipate that the cost of an installation can be recouped from savings in energy costs in less than five years. This estimate appears to take into account some subsidies and low-cost loans but does not take into account RHI payments i.e. ROI may be increased when factoring RHI payments.

Name

Telephone

Website

Alternative Heat Ltd

11 Burrenreagh Road Castlewellan, County Down BT31 9HH

Northern Ireland

02843 770700

www.alternativeheat.co.uk

Baystar

Beechover Court, Forest Road Colgate

Horsham

RH12 4SY

01293 851459

www.baystar.co.uk

Calibrate Energy Ltd

West Ditchburn Farm Alnwick Northumberland NE66 2UE

01665 578638

www.calibrateenergy.co.uk

Earth Source Energy

Unit 6 Silver Birches Business Park Aston Road

Bromsgrove Worcestershire

B60 3EU

0330 22 33300

www.earthsourceenergy.co.uk

Ember Energy

1 Fleming Street Darvel Ayrshire

KA17 OED

01563 501582

www.emberenergy.co.uk

Finn Geotherm Ltd

Wood Farm, Deopham Road Attleborough

Norfolk

NR17 1AJ

01953 453240

www.finn-geotherm.co.uk

JKN Renewables Ltd

Office Suite 4

The Gables Business Park Belton Road, Epworth Doncaster

DN9 1JL

01427 874308

www.jknrenewables.co.uk

Q-Gen Heat Pumps Ltd

St Pegs Mill, Thornhills Beck Lane Brighouse

West Yorkshire

HD6 4AH

01484 475808

www.q-gen.co.uk

Yorkshire Renewable  Energy Systems

Evans Business Centre Monckton Road Wakefield

West Yorkshire

WF2 7AS

07766 555550

www.yres.co.uk

 

Manufacturer

Name

Telephone

Website

Alto Energy Ltd

Hexagon House, Avenue 4 Station Lane, Witney Oxfordshire

OX28 4BN

01993 220699

www.altoenergy.co.uk

Dimplex UK Ltd

Millbrook House, Grange Drive, Hedge End

Southampton

S030 2DF

0844 8793588

www.dimplex.co.uk/heat-pumps

 

Kensa Heat Pumps

Mount Wellington Chacewater

Truro

TR4 8RJ

01872 862140

www.kensaheatpumps.com

 

Klimadan

A/S Jylland, Rømersvej 30 7430 Ikas

Denmark

+45 96277070

www.klimadan.dk

Pellon Group

Oy Yrittäjäntie 10 62375 Ylihärmä Finland

+358 6 4837 555

www.pellon.fi/en

Star Renewable Energy Thornliebank Industrial Estate Nitshill Road

Glasgow

G46 8JW

0141 6387916

www.neatpumps.com

Vaillant Group Ltd Nottingham Road Belper

DE56 1JT

01733 596109

www.vaillant.co.uk


Discover more about slurry

Tips, tools and advice on slurry and manure management to help dairy, pig and beef farmers to reduce costs, add value and protect the environment.

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