Using waste to generate energy One of our biggest waste streams is sewage from homes and businesses – the sludge from our waste-water treatment is 55% of our total dry waste. We realised 50 years ago that we could generate renewable energy from this. We exported 245 GWh of green gas and generated 319 GWh of electricity from 35 Anaerobic Digestion ('AD') sites this financial year, enough to power around 90,000 households with electricity and 18,000 with gas for a year. This generation replaces fossil fuels that otherwise would have been required, and avoids 19,000 tonnes of carbon dioxide equivalent (CO2e). We use this energy to power our sites wherever we can. We continue to invest in our AD operations, and we’re upgrading from conventional digestion to a Thermal Hydrolysis Process (‘THP’). This uses heat and pressure to break down the sludge before digestion, which is more efficient and yields more gas. Extracting valuable products from waste Sewage sludge ends up as more than just energy. Our AD operations produce about 145,000 dry tonnes of treated biosolids a year that can be used as agricultural fertiliser, reducing the need to produce conventional fertiliser, and the greenhouse gas emissions associated with that. Our food waste plants, too, produce a rich digestate (the residue after gas is created), highly valued by agriculture. Our composting facilities produce a certified soil improver. We are also looking at other opportunities to recover resources from sludge. At our Nottingham waste-water works, we recover nitrogen and phosphorus in the form of struvite, which has potential for fertiliser use. We have run demonstration trials of other nutrient removal outcomes, such as producing ion exchange and algal bioreactors. Fertilising innovation We’re working with CCm Technologies to test production of a high-grade fertiliser pellet that uses biosolids, recovered ammonia and CO2 from our waste-treatment plants. It’s win-win-win – a saleable product, a fertiliser that helps reduce nutrient run-off, and avoids emisions. Making our material use circular We continue to work with Bureau Veritas to audit our different waste streams to give us better visibility. This year we diverted 87% of our audited waste from landfill. We achieved a 100% landfill diversion rate for Bio Solids. We are now also setting demanding targets for reducing material use, and reusing, recycling and recovering across all waste streams. We prioritise this based on evidence of each material’s relative impact and environmental importance. Office and facilities management We already achieve up to 99% diversion from landfill in some categories of facilities waste such as sanitary waste. In practice, improving this across the board means: being selective and prudent in procurement and use of materials, ensuring items are produced sustainably; prolonging the operational life of everything we use; and preserving as much value as we can when things reach the end of their useful life. Sometimes it means targeting materials specifically for their prominence or the effect they have culturally – for example removing single-use plastic cups and bottles from our head office, a practice we’ll extend to other sites (though COVID-19 safety practices have made this more difficult this year). Or increasing the rate of paperless billing from the current 42%. Civil engineering Waste tonnage is a crude measure of the impact on the environment. So we are building on the data collected from our Scope 3 emissions mapping to identify and target the highest-impact areas of our material use. For example, embedded carbon is a bigger issue with some materials, and we look to reduce the greenhouse gas emissions associated with concrete and steel through: looking to source low-emission product; reducing material use by re-thinking asset design and management; finding ways to extend the life of our infrastructure; and working extensively with our contractors and suppliers to influence their operations, a major challenge we’re at the early stages of addressing. While our business is rooted in the natural environment, we depend on systems of engineered infrastructure, plant and machinery. Thinking in systems, it’s only natural for us to engineer for efficiency, design out wastage, and find smart ways of making the most of our resources. 1. Excludes waste infrastructure 2. Waste Electrical and Electronic Equipment Total waste 2020/21 tonnes of CO2e avoided by using waste to generate renewable energy landfill diversion rate for our audited waste streams 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 8 9 0 % Looking after the world around us Making the most of our resources