In an effort to further reduce its carbon footprint, Southern Water is turning to sewage to boost renewables generation. At present, the water and sewage company generates 17 percent of its electricity demand from 16 combined heat and power (CPH) sites, with total renewable electricity generation currently totaling 48.3GWh. With new Veolia combined heat and power (CPH) engines installed at its treatment facilities in Hampshire and Kent, Southern Water will be well equipped to expand its renewables portfolio.
The new projects at Hampshire and Kent have seen Veolia implement project design, installation and operation of biogas cogeneration units, which converts wastewater from Southern Water’s 39,000 kilometers of sewage networks into biogas through anaerobic digestion (AD).
On their own, the new systems have the potential to reduce the company’s carbon footprint by 3,600 tons and in conjunction with existing CHP systems purchased by the firm, could reduce CO2 emissions by 8,800 tons. This equates to the removal of 5,800 cars from the road.
“Recent estimates show that biogas from the sludge resource could deliver an estimated 1,697GWh each year — enough electricity to power over half a million homes. This latest extension of the use of CHP by Southern Water clearly demonstrates its commitment to further the sustainability of the water industry,” said Veolia COO Gavin Graveson.
Approximately 190 wastewater sites across the UK now use on-site biogas production methods. Yorkshire Water’s Knostrop site in Leeds is one of the most ambitious. By 2019, the new facility is expected to process 131 tons of dry sludge per day, generating 55 percent of the site’s energy requirements and helping achieve 94 percent recycling of the region’s sludge by 2020.
The biogas captured by the AD process at Southern Water’s sites will provide electricity to power the company’s wastewater treatment operations. Any surplus electricity will be fed to the grid and heat recovered from the CHP units is used to speed up the AD process.
“The capturing of biogas is a double win because not only do we collect free fuel but we also prevent the release of methane which has a global-warming potential 25 times more potent than carbon dioxide,” said Martin Ross, Southern Water’s energy manager.
While biogas is gaining momentum in the UK, research from the UN University’s Institute for Water, Environment and Health has pointed to biogas providing as providing a viable solution for curbing emissions in developing countries. Safely obtained biogas from human waste could generate electricity to power all of the households in Indonesia, Brazil and Ethiopia combined.