Sustainability
We operate in a material world. And as you'd expect, in taking care of water - one of life's essentials - we're careful to make plans and build systems that add up. So you can count on us to be fastidious and measured in our use of resources.
Our aim is to engineer for efficiency, design out wastage, and champion in the skills and learning needed to get this right.
As much as our business is rooted in the natural environment, we also depend on extensive, connected, and carefully calibrated systems of engineered infrastructure, plant, and machinery. Thinking in systems is part of our worldview - so it’s only natural for us to engineer for efficiency, to design out wastage, and to find smart ways of making the most of the materials under our stewardship.
Thinking about waste as just a resource in the wrong place opens up a world of opportunity.
By adopting a circular economy approach in all areas of our business, we are able to use less of the world’s finite material resources and reduce the impact of their extraction on nature and biodiversity; generate cost savings; reduce waste; and lower our greenhouse gas emissions.
Our material footprint as a company combines three key activities.
First, like many other businesses, our facilities management, fleet, office and IT needs.
Second, our construction and civil engineering work - digging, building, repairing, shifting large amounts of earth, and deploying construction materials at volume to keep our water and sewage networks running.
And thirdly, we are a waste processor at heart - we take sewage and food waste from homes and businesses, and convert them to biosolids with beneficial nutrients for farmers.
Our priorities for making the most of our resources
For many years we have been a leader in converting sewage to energy and fertiliser using anaerobic digestion, and we are now applying this expertise to food waste too. We know that emerging technologies will allow us to extract even more value from waste, and this will continue to be a core focus for our innovation and investment. In the rest of our business, our comprehensive waste audit data provides the starting point for pinpointing areas of focus for our zero landfill aspiration, and we now need to maintain our efforts to meet the government’s ambition of zero avoidable waste by 2050.
But we know that landfill diversion is only part of the picture. As much as we can, we need to use less and utilise our existing resources better. Understanding in more depth the relative impacts of different waste categories will allow us to prioritise our actions as we look to reduce overall waste generation in addition to optimising end of life. We will increasingly look upstream to our supply chain to identify opportunities to reduce material use and source more sustainably.
Our priorities are:
Turning waste into resources and energy
Making our material use 'circular'
Embedding circular economy principles
Our overall ambition is to embed and apply circular economy principles across the business:
- Through our design and procurement processes, we will identify opportunities to use less
- What materials we do need, we will source responsibly, minimising environmental footprint
- We will recover resources and energy from waste water
- We will make maximum use of all of our assets, repairing and extending life where possible
- At end of life, where others see waste, we see opportunity, to recover, regenerate and create value
Turning waste into resources and energy
As a water company, one of our biggest waste streams is sewage from homes and businesses. The sludge produced as part of our wastewater treatment process makes up 55% of our total audited dry waste.
Our two biggest opportunities for valorising’ sewage are:
- Using waste to generate energy
- Extracting valuable products from waste
Using waste to generate energy
We realised 50 years ago that sewage sludge was in fact a valuable product that we could use to generate renewable energy.
Today we are the UK leader in the production of biogas from sludge through anaerobic digestion. In addition, our UK award-winning food waste and green waste recycling business Severn Trent Green Power processes a quarter of the UK’s food waste using AD and composting, and together our bioresources and food waste plants make us the biggest AD operator in the UK.
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).Across Severn Trent group we generate renewable electricity and gas equivalent to 53% of Severn Trent Water’s electricity use.
We will continue to invest in expanding and improving our AD operations, including upgrading from conventional digestion to a Thermal Hydrolysis Process (THP). This uses heat and pressure to break down the sludge before digestion, resulting in a more efficient process, an enhanced product and higher gas yields.
Our AD operations produce around 145,000 dry tonnes of treated biosolids
Extracting valuable products from waste
Sewage sludge contains far more potential than just the energy that can be generated. Our AD operations produce around 145,000 dry tonnes of treated biosolids which we send to agricultural land as fertiliser, reducing the need for production of conventional fertiliser, a significant source of greenhouse gas emissions.
Our food waste plants, too, produce a digestate rich in nitrogen, potassium, phosphate and other trace elements that is highly valued within the agricultural community. Our composting facilities produce a soil improver that is PAS 100 and Compost Quality Protocol certified.
In addition, we are creating opportunities to recover other resources from sludge, such as nitrogen, ammonia, phosphorus, nutrients and cellulose. We already have a full scale plant that recovers nitrogen and phosphorus in the form of struvite at Nottingham wastewater treatment works and we have delivered a range of demonstration scale trials of other sustainable solutions for nutrient removal such as ion exchange and algal bioreactors.
Recycling grit and screenings is another area of focus where we know there is potential for improvement through composting or use in construction.
The more efficiently we can extract valuable products from waste, the more we are supporting the delivery of a circular economy that protects the earth’s resources and environment.
Spotlight: innovation
A lot of what will be needed to solve the climate and nature emergencies hasn’t been invented yet. So we know we need to innovate. This is relevant across all pillars of our environment strategy. And all parts of our business.
That’s why we’re committed to creating the conditions required for innovation to happen. Our open innovation model allows us to actively seek and bring new ideas into the
water industry. We bring in research skills from universities or license our intellectual property to manufacturers, to enable them to deliver new goods and services into the
water industry. A good example of this is our new £5m Resource Recovery and Innovation Centre near Birmingham, which is a testbed for new technologies and processes, open
for collaboration with technology providers, academics and others.
The outcomes of innovation can be highly technological, or they can be simple - ‘appropriate’ technology. Either way, we embrace innovation as a critical part of our route to the future.
LeakFinder ST. Detecting and pinpointing leaks quickly and without having to resort to multiple excavations will be critical to our ability to conserve water resources and reduce disruption to our communities and customers. LeakFinder ST is a new patented technology, developed with our technology partner Echologics, which integrates sophisticated echolocation and computer processing technologies to help us quickly and cost effectively map leaks across our network.
Phosphate Socks. These don’t involve complex or sophisticated technology. But they are a highly effective solution to the important and expensive problem of phosphate run-off from agricultural fields, into watercourses. Phosphate Socks are large, long fabric bags, containing material which absorbs phosphorus and sediment. They are easy to deploy strategically near to watercourses, to intercept flow lines of potential phosphorus run-off. And they’re cost-effective. Our trials have suggested they could remove up to 99% phosphorous in run-off. This could save us £13M in capital costs in just one catchment!
Scaling innovation requires investment
We are now in a position to tap into additional sources of debt funding to support our sustainability ambitions, through our Severn Trent Sustainable Finance Framework. In March 2020 we completed our first debt issue under the framework, which was used to assist in the development of our Severn Trent Green Power business. In June 2020 we issued our first sustainable bond, with a value of £300m, used to finance green and social projects across the business.
Making our material use ‘circular’
We are now bringing the circular economy thinking and approach from our AD operations and applying it to the rest of our business.
We are already making good progress in reducing waste to landfill, diverting 87% of our audited waste from landfill. But we are now going beyond this by exploring how we can set ourselves targets not only for landfill diversion but also for material use reduction, reuse, recycling and recovery across all waste streams.
We guide and prioritise this based on evidence on their relative impact and environmental importance. The two largest areas of our business that this applies to are:
- Office and facilities management
- Civil engineering
Office facilities and management
We already achieve up to 99% diversion from landfill in some categories of facilities waste. Improving on this means ensuring that we are working as high up the waste hierarchy (reduce, re-use, recycle) as possible. In practice this means:
(1) being selective and prudent in our procurement and use of material resources,
(2) prolonging the operational life of everything we use, and
(3) at end-of-life, we preserve as much value as we can. (It also means looking at provenance; that is, how what we use is sourced and manufactured, to ensure that it is sustainably produced using the earth’s resources judiciously.
We will put our principles into practice in all parts of the business, in some cases targeting materials specifically for their prominence, and their potential to effect culture change. So we have removed 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).
There are other areas too, where we can work with our customers to reduce waste generation, such as increasing the rate of paperless billing from the current 42%.
Civil engineering
While waste from office and facilities is associated with some of our highest value and impact waste - such as cabling, and rare earth metals components in electronics, our capital works - construction and maintenance activities - use the largest volumes of material. Of this, excavated highway waste is one of our most significant categories of waste by weight - around 87,000 tonnes a year - and we currently divert two thirds of this away from landfill, a figure we are working to increase.
However, waste tonnage is only a crude measure of the impact of material use on the environment. We use data to actively target the highest impact areas of our material use. So for example, we will specifically target the GHG emissions associated with concrete and steel through: (1) developing opportunities to source low-emissions product sources, (2) reducing material use through re-thinking asset design and management, and (3) finding ways to extend the life of our infrastructure through technology and good stewardship.
Working in this way requires evidence and analysis. So we will build on our Scope 3 emissions assessment to gather other relevant data to allow us to assess the most impactful areas for action.
Putting the circular economy into practice across our business will also mean working extensively with our contractors and suppliers to influence their operations. This is a big challenge, and one where we are early on in the journey. Our ambition is to create an approach that can be embedded across working practices, policies and procedures. This will include supplier selection processes and contractual criteria, as well as engaging in joint initiatives and partnerships to push innovation in key areas.
Making the most of our resources: our to do list
- Zero avoidable waste to landfill
- Build on our waste audit by identifying the most impactful waste reduction opportunities
- Create and embed a circular economy approach across the business
- Assess supply chain material use and identify key opportunities for improvement
- Identify opportunities and approaches for working with suppliers and contractors
- Continue to invest in innovation to drive extraction of resources from sewage sludge
If you'd prefer, you can download a PDF version of Caring for our Environment [PDF].