Supporting Scottish Water in achieving net-zero emissions by 2040
Scottish Water has committed to achieving net-zero emissions across all operational and capital investment activities by 2040. Ramboll has been a partner to Scottish Water Horizons Ltd (a commercial subsidiary of Scottish Water that works to encourage growth and invest in renewable technologies) since 2009, supporting the company with projects that will help them achieve their net-zero goals.
When the client says it better
Scottish Water Climate Emergency Response
Scottish Water, publicly owned by the Scottish Government, operate a significant number of water and wastewater treatment sites as well as supplying water to over 2 million properties and running all logistics and supporting services.
In April 2019, the Scottish Government declared a Climate Emergency Response and committed Scotland to achieving net-zero greenhouse gas emissions by 2040.
The Scottish Water route map includes increasing the amount of renewable energy generated and/or hosted on their sites, leading on biogas generation and the recovery of heat from wastewater.
Eight projects over ten years and the journey continues
During ten years of collaboration, Scottish Water Horizons Ltd and Ramboll have worked on eight projects. From a client-supplier relation, the collaboration has developed into a partnership based on trust with regular discussions and brainstorming new ideas on how to achieve the net-zero goals.
One of the first projects performed by Ramboll for Scottish Water Horizons Ltd was the Dalderse Anaerobic Digestion feasibility study. The project was one of the first steps in the development of the biogas industry within the UK. Water companies which already had anaerobic digesters on site were in a good position to improve and invest in their existing assets. Biogas as a renewable fuel not only had environmental benefits, but could offer a financial incentive, by savings in vehicle fuel or by sales to the gas grid, to those who invest in it. Ramboll considered all the available biogas upgrade technologies in order to determine the most appropriate technology for this facility.
Bringing the Scandinavian model into play
Inspired by the Scandinavian model where more and more utility companies are looking into innovative ways of recovering energy from wastewater, Scottish Water Horizons Ltd engaged Ramboll in another pioneering project, Stirling Energy Centre and district heating network (DHN), that enabled the delivery of low carbon heat across the large area of Stirling.
Put simply, a system was created to extract natural heat from sewage and convert it into usable low carbon energy to power the DHN. The Energy Centre was designed to use heat from several generation units comprising a combined heat and power (CHP) unit, with electrical output used to power a ‘SHARC’ sewage heat recovery system. The system also integrates heat from boilers using biogas generated from the existing anaerobic digestion plant. The heat produced from the CHP and the heat recovery units is then distributed to consumers in a low temperature (60/40) district heating network. The large sewer heat pump was the largest installation in the UK, and the first to supply multiple customers via a district heating network.
Hydrogen playing a great role in achieving the net-zero goals
Scottish Water Horizons Ltd and Ramboll are currently investigating, through an innovative hydrogen project, the opportunity to use final effluent, which is discharged to watercourses, to produce hydrogen and to decarbonize Scottish Water’s vehicle fleet while feeding the oxygen into their aeration lanes to enhance biological treatment processes.
The carbon emissions savings associated with switching from diesel to hydrogen for transportation fuel were estimated using diesel vehicles as the counterfactual. The estimate was that Scottish Water’s transport fleet could save 82% of carbon emissions which would equate to 1.4% of overall Scottish Water carbon emissions by 2040. The project could achieve a financial payback, but this would be improved if on-site renewable electricity generation could be included.