Biogas can help reduce greenhouse gas emissions from pig production - both in agriculture and at the slaughterhouse. These are the results of a new scientific report.

Greenhouse gas emissions from pig production can be reduced by up to 20 per cent if animal manure is degassed and the biogas is used to produce electricity and heat. Biogas can offer producers a competitive advantage in relation to consumers who prefer the most eco-friendly meat.

According to a research team from Aarhus University in Denmark, biogas can improve the environmental impact of pork meat because the majority of greenhouse gas emissions occur on the farm, i.e. before the animals get to the slaughterhouse.

The precondition for the Danish calculations is that the biogas is used to power a gas engine producing electricity and that the water used to cool the engine is used to supply heat to e.g. private housing or industrial facilities, and biogas is thus a substitute for fossil fuels in the production of electricity and heat.

Greenhouse gases from agriculture

In 2007, massive potential for biogas was documented in the report 'Environmental Assessment of Danish Pork'.

In spring 2011, scientists Thu Lan T. Nguyen, John E. Hermansen and Lisbeth Mogensen published a revised version of this report. The report describes how greenhouse gas emissions are distributed in the pork meat chain, from agricultural production, to the slaughterhouse and transportation - thus demonstrates why there is such important potential for biogas. The report explains that most greenhouse gases are emitted before the pigs arrive at the slaughterhouse.

According to the new report, greenhouse gas emissions are 3.1 kg of CO2 per kg pork by the time the pork meat leaves the slaughterhouse. Of this total, slaughterhouse production accounts for 0.2 kg, while on-farm production accounts for greenhouse gas emissions corresponding to 2.9 kg of CO2 per kg of pork (carcass weight).

Within agricultural production, 60 per cent of emissions originate from animal feed and 30 per cent from greenhouse gas emissions from the individual pig farms.

Most emissions from a pig farm are methane gas from manure. In terms of reducing greenhouse gas emissions, there is huge potential in degassing manure and utilising methane to produce green energy as a substitute for energy from fossil fuels.

Biogas reduces the environmental impact of the slaughterhouse

According to one of the authors of the report, John E. Hermansen, another significant finding is that production at the slaughterhouse accounts only for 0.2 kg per kg of pork meat (carcass weight). According to the research team, this is because Danish slaughterhouses also utilise parts of the pig that are not sent out to consumers.

"About 25 per cent of the pig is not sent onto the consumer market. These by-products are utilised in biogas production and made into meat and bone meal for use in animal feed. This represents effective utilisation of the by-products as biogas production helps reduce environmental impact," explains John E. Hermansen.

Transportation is insignificant

At the same time, the research indicates that meat transportation has a relatively insignificant effect on overall environmental impact.

If, for example, you transport pork meat 600 km in a refrigerator truck, the resulting greenhouse gas emissions amount to about 149 g of CO2.

In this case, transportation accounts for 4.7 per cent of the total greenhouse gas emissions of the meat on the truck. Slaughtering processes account for 5.6 per cent. The vast majority, 89.8 per cent, of the greenhouse gases emitted from the pork production chain, is produced on the farm.

The authors of the report present several other transportation examples and their principal conclusion is most greenhouse gases emitted from pork meat production are emitted at the agricultural production stage.

And it is therefore here you will find the greatest potential for reducing emissions, and in this context, biogas is the primary potential means to reduce these emissions.

"In 2007 we concluded that degassing manure would reduce greenhouse gas emissions by 20 per cent. This figure still holds water. In this respect, the findings of the new report change nothing," John E. Hermansen explains.

You can download the report 'Environmental Assessment of Danish Pork' here: http://web.agrsci.dk/djfpublikation/index.asp?action=show&id=1115]