3. Improving pig barn insulation Current systems frequently use fibreglass wool to insulate the pig housing facilities. While this is a cheap (€ 11.3 per m2 good option (U value = 0.33 W/m2
) and K), the study explored the
environmental and economic performance for the more ex- pensive (€ 16.7 per m2 0.16 W/m2
) but also more effective (U value = K) polyurethane boards to improve barn insula-
This pig produ- cer is insulating part of the roof of his pig house.
2. Slurry acidification using sulphuric acid The environmental benefits of slurry acidification are achieved by reducing ammonia emissions. In-house slurry acidification with sulphuric acid was specifically tested, and this study confirmed its large abatement potential for the acidification (-24.6%) and eutrophication (-11.4%) impact categories. Although an automated process, acidifying slurry in pig housing requires a significant investment (~€ 800,000 at year 0), considering the costs for an acidification plant and slurry pumping system, electricity for their operation and the addition of calcium carbonate to counterbalance the acidic effect of slurry when this is applied on fields. According to the study, slurry acidification was the most cost-effective strategy for the mitigation of acidification and eutrophication potential, although they incur additional costs of € 303 per tonne SO2
eq. and € 1,190 per tonne PO4 each category respectively, see Figure 2.
potential, expressed in log10-transformed euros per tonne of
sulphur dioxide equivalents (tonnes SO2 eq.) to capture the the annual abatement potential of each measure considered.
1.00 2.00 3.00 4.00 5.00 6.00
0.00 9.52 0.332 2.03 2.05 0.632 0.540 0.445 0.406 tonnes SO2 eq. abated per year
16 ▶PIG PROGRESS | Volume 36, No. 10, 2020 Acid IVE IVE & ISD ISD IVE & IMIN IMIN IVE & FSR FSR 3- eq. for
tion. The findings showed that this strategy has potential to improve system environmental performance for global warming potential (-1.33%) and non-renewable energy use (-4.37%), by contributing to more stable indoor climate con- ditions and therefore reducing energy consumption for cli- mate control. Furthermore, potential reductions for acidifica- tion (-1.40%) and eutrophication (-0.174%) were identified due to less variability in indoor temperature, which affects ammonia emissions. Although this strategy required a small- er investment (~€ 53,400 at year 0), due to the relatively small abatement potential it exhibited it did not rank particularly high in cost-effectiveness for any of the impact categories it mitigated. However, in addition to environmental impact re- ductions, potential improvements in animal welfare due to the provision of stable indoor climate conditions should be considered among the benefits associated with the implementation of this strategy.
4. Increasing ventilation system efficiency Similar to barn insulation, indoor ventilation rates largely dic- tate indoor climate conditions and also have a direct effect on ammonia emissions from slurry in the building. The study in- vestigated the whole-farm environmental and economic con- sequences of investing in more frequent maintenance (+50%) of the fan system and dusting of the surrounding components (i.e. air inlets, ducts) to achieve a 20% increase in ventilation efficiency throughout production. Interestingly, this relatively small investment (~€ 232,000 over a 25-year time horizon) achieved significant abatement potential across all impact categories tested and ranked among the more cost-effective of options tested. However, it incurred additional costs for the mitigation of all environmental im- pacts assessed. Specifically, for global warming potential and depletion of fossil fuel, where it achieved the largest reduc- tions (-1.79% and -4.60% respectively), it required € 0.03 per tonne CO2
eq. and € 2.29 per GJ mitigated.
5. Removing slurry more frequently Frequent slurry removal is a laborious task; however, it can significantly reduce ammonia emissions at pig housing and improve pen hygiene. The study evaluated the environmental and economic consequences of weekly slurry removal, as op- posed to the monthly removal that represented baseline con- ditions in Danish pig farming systems. This strategy exhibited some abatement potential, mainly for acidification (-1.05%) and eutrophication (-0.202%). However, due to the costs
log10 transformed € / tonne SO2 eq.
PHOTO: KOOS GROENEWOLD
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