ENVIRONMENT ▶▶▶
Six on-farm environmental mitigation strategies
BY GEORGIOS PEXAS, NEWCASTLE UNIVERSITY, UK T
he research team evaluated the cost-effectiveness of several environmental abatement strategies relat- ed to pig housing and manure management, using an integrated life cycle assessment (LCA) based
framework that combined whole-farm environmental and economic models. Their findings have been published in the peer-reviewed journal Agricultural Systems. The study simulated the implementation of the strategies and tested their performance based on a 500-sow, integrated Danish pig farming system that produced about 13,000 slaughter pigs annually. The environmental LCA evaluated potential environmental impacts associated with harmful emissions from the pig farming system (e.g. greenhouse gases, ammonia emissions), which are significant contribu- tors to global warming, acidification of ecosystems and eu- trophication of freshwater bodies. The economic LCA com- prised a discounted cash flow analysis of any cost (i.e. capital, fixed and operational costs) and revenue streams (e.g. reve- nues from pig meat sold, manure sold as fertiliser), identified throughout the entire pig production process (cradle to farm gate). The economic performance of each environmental abatement strategy was evaluated on a 25-year time horizon. Six strategies are discussed below. The order is random and does not reflect preferences of the research team.
1. On-farm anaerobic digestion of slurry From an environmental perspective, anaerobic digestion of slurry exhibited great potential to reduce system global warming potential (-3.17%) and improve its performance with regard to the depletion of abiotic resources (-14.7%) and fossil fuel (-33.5%). These benefits arise mainly from the gen- eration of electricity and heat that can be discounted from on-farm energy use, as well as the improved efficiency of the nutrient-enriched digestate as synthetic fertiliser replacement. Considering also the capital and operating costs of a com- bined heat and power plant, and fees for connection to the electricity grid, implementing this strategy may require a very large investment (in this study, € 1.8 million additional invest- ment costs in year 0). However, under certain conditions (de- tailed in the specific assumptions of study) the energy con- sumption and fertiliser discounts may result in increased
Reducing the environmental impact of pig farming systems has been a key sustainability challenge for the 21st
century. Many alternative farm management
strategies can achieve reductions in environmental impact categories. Researchers at UK’s Newcastle University looked at various systems and compared their cost-effectiveness.
whole-farm profitability (+13.2% in this study). The external factors – conditions that can affect this strategy’s economic performance – should be considered prior to its implementa- tion, particularly when comparing its cost-effectiveness in different systems and locations. The most important of these factors include the specific electricity tariffs and the availability of relevant investment support schemes. In this specific case study, anaerobic digestion was identified as the most cost-effective strategy in reducing system global warming potential and non-renewable resource use, generat- ing € 0.2 per tonne CO2
eq. and € 0.05/g Sb eq. mitigated, respectively, as additional farm profits, see Figure 1.
Figure 1 - Cost of abatement for mitigation of global warming potential, expressed in log10-transformed euros per tonne of
carbon dioxide equivalents (tonnes CO2 eq.) to capture the large annual abatement potential of each measure considered.
0.10 0.30 0.50 0.70 0.90
–0.10
206 156 215 275 88.3 114 258 216 200 65.7 150 56.1 tonnes CO2 eq. abated per year
AD & IVE IVE
AD IVE & FSR & AD IMIN AD & IMIN IMIN & IVE & AD
IVE & IMIN IMIN & IVE & FSR & AD IMIN & FSR & AD AD & FSR
IVE & FSR
anaerobic digestion.
▶PIG PROGRESS | Volume 36, No. 10, 2020 15
log10 transformed € / t CO2 eq.
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