The process of distilling whisky creates by-products
that can be a feed source for sheep and cattle.
This report looks at the entire lifecycle impacts of using some forms of these by-products in renewable energy, traditional animal feed or concentrated dark grains animal feed.
The initial report was published in November 2017, and shared with key stakeholders. We were asked what happened when only draff was produced (i.e., no pot-ale), which prompted a further analysis.
We found a negligible difference between the renewable energy and animal feed scenarios. However, when draff was used to produce renewable energy to replace heavy fuel oil, this had a significant benefit over its use as an animal feed.
- All three scenarios were found to have a net beneficial climate change impact, offsetting GHG emissions by avoiding the production of energy, animal feeds and/or fertilisers by other means.
- The renewable energy scenario offset the largest amount of GHG emissions overall.
- While the two animal feed scenarios perform better in certain life-cycle phases, such as capital burdens and material use, the generation of renewable energy avoids a significant amount of carbon through the offsetting of grid electricity and heat.
- The sensitivity of these results to some underlying assumptions was tested during the study:
- it was found that switching the offset cattle feedstock from rape meal to soya bean meal slightly increases the GWP benefits for the two animal feed scenarios;
- including woodchip co-firing significantly increases the GWP benefits for the renewable energy scenario;
- assuming that any heat produced would offset heavy fuel oil (rather than natural gas) improved the GWP results for all three scenarios to varying amounts.
- However, the overall positioning of the three scenarios was unaffected by the sensitivities modelled; the renewable energy scenario remained the most favourable.