Environmental Assessment of Danish Pork

by 5m Editor
24 May 2011, at 12:00am

Using the attributional approach as prescribed in the PAS 2050, the environmental impact of each kilo of Danish pork leaving the slaughterhouse is estimated to 3.1 kg CO2e in global warming, 243 g NO3e in eutrophication, 56g SO2e in acidification, 21 MJ primary non-renewable energy, and 5.8 m2a in land use, according to Thu Lan T. Nguyen, John E. Hermansen and Lisbeth Mogensen of the University of Aarhus, Denmark.

The aim of this report is to present an environmental profile of Danish pork through a life cycle assessment (LCA).

In LCA two different approaches are often used: an attributional approach and a consequential approach. Basically, the attributional approach describes the resources used and emissions engendered to produce the product in question (here one kilo of pork), whereas the consequential approach accounts for the resources used and associated emissions when producing one kilo of pork more.

This choice of methodologies impacts on the results, since the attributional approach uses information of impacts related to, for example, the specific feed production, whereas the consequential approach relies on data on, for example, the environmental cost to produce the feed necessary for the production of one extra kilo of pork.

Both methods are being used and a previous life cycle assessment of Danish pork used the consequential methodology. However, the Publicly Available Specification for documenting the global warming potential or the carbon footprint of a product, (PAS 2050), requires the attributional approach to be used.

In the present report, therefore, the assessment used both methods. The PAS 2050, in addition, has the option of including the impact on the global warming potential of land use changes following the production of feed. The basis for doing this is, however, not sufficiently developed, and therefore this aspect was not included in the present work for any of the methods. If included, the global warming impact would be higher.

The environmental assessment was performed using data representing the typical Danish pork production in 2010 on the one hand, and on the other using data from the 25 per cent of Danish pig herds with highest technical efficiency in terms of piglets per sow and feed use per kilo of pork produced. Based on the historical development, these herds will, in a few years time, be representative of the typical Danish pig production. The assessment was performed as if the pig production were a landless business where all feeds etc. need to be imported and all manure exported. The methodology used ensures that the results will not differ from a situation where the farmer produces part of the feed and uses part of the manure for this purpose on his own farm.

The environmental impact was expressed per ‘one kilo of Danish pork (carcass weight) delivered from the slaughterhouse’.

Five impact categories were considered: global warming potential; acidification; eutrophication; non-renewable energy use, and land use.

Table S1 summarises the environmental performance with respect to the five impact categories expressed in equivalents (e) of the respective impact category.

As shown in the table, the estimated environmental impact is higher when using the consequential approach than when using the PAS 2050. This reflects primarily that the average feed cereals produced under Danish conditions are estimated to have a lower environmental impact than what is estimated for the marginal production of cereals on the world market, partly due to higher yields per hectare and partly due to stricter environmental regulations in Denmark, which in particular decrease eutrophication and global warming impacts as well as land use requirements.

Compared to earlier results for Danish pork based on 2006 data and using the consequential approach, this work is based on updated emission coefficients and housing conditions, which makes a comparison difficult. Nevertheless, the global warming impact was slightly lower in the present work (0.2kg CO2e per kilo of pork) probably reflecting the improvements that have taken place in cereal production and pig rearing in the period.

The environmental burden of the pork is primarily related to the farming stage and less so to the slaughtering stage product. Thus, less than 0.2kg CO2e per kilo of pork (or six per cent) is related to the slaughtering stage. Therefore, increased efficiency in the primary stage impacts considerably on the total environmental impact of the pork. This is illustrated also in Table S1, which shows that the pork from the 25 per cent of pig herds with highest technical efficiency has an eight to 10 per cent lower environmental impact than the average.

Table S2 shows the contribution of different key elements to the different environmental impact categories at the farming stage expressed per kilo live weight of pig leaving the farm. Total impact per kilo live weight is estimated at 2.2kg CO2e for the typical Danish production after the PAS 2050 model. As the table shows, ‘feed use’ and ‘on-farm emissions&sdquo; are the two major contributors at approximately 60 and 30 per cent, respectively, of the total impact, whereas ‘transport of feed’ and ‘on-farm energy use’ are minor contributors.

The major contributor to feed use impact is cereal, which illustrates the importance of having a very environmentally efficient cereal production.

The main contribution to ‘On farm emissions’ is from methane emissions from the manure and – to a lesser extent – N2O emissions. These emissions can be reduced by manure management procedures and represent as such an improvement potential. For acidification approximately one-third of the total impact is related to the on farm emission of NH3 illustrating the importance of efforts to reduce this.

The manure produced results in emissions at the farm but it also has a value as a fertiliser, thus substituting synthetic fertiliser. Danish regulations stipulate that 75 per cent of fertiliser nitrogen has to come from manure on a total nitrogen basis. Even though there are higher transport costs related to manure handling and that field emissions are relatively higher using manure, because the substitution rate is not 100 per cent, the net effect is a saving due to saved CO2e emissions related to fertiliser production. In the typical case, the net effect is a saving of 0.03kg CO2e per kilo of pork produced.

A recent literature review arrived at a reference value of the climate impact associated with the primary production of one kilo of pork of approximately 3.3kg CO2e per kilo carcass weight leaving the pig farm. In this assessment of typical Danish pork, the researchers arrived at a value from 2.9 to 3.3kg CO2e per kilo of carcass weight leaving the farm, lowest with the attributional approach, which is the approach mostly widely used in different studies, thus well below the reference value given in literature.

Table S3 shows that total emission of pork after transport in three situations based on the PAS 2050 approach. It appears that the cooled transport situations hardly changes the total impact compared to Table S1. The freezing followed by intercontinental transport mainly increase energy use (27 per cent), followed by global warming (16 per cent) and acidification (14 per cent).

Further Reading

- You can view the full report by clicking here.

May 2011