Thames Water do not just provide water for 9 million people in and around London but also recycle the wastewater of around 14 million people. This sewage has a very large potential for creating electricity via anaerobic digestion (AD). Thames Water, who have embraced AD technology, create 40% of the water industry’s renewable energy by these means and consider themselves as ‘market leaders’ in this field.
The seven step process Thames Water implement to transform waste to electricity begins with waste water being pumped to a local sewage treatment plant. Here, it is then left to settle before going through various cleaning techniques until the water is ready to go back into a watercourse whilst the waste is put into a digester. Here it gets heated, in an oxygen free environment, until it naturally breaks down (anaerobic digestion) which in turn produces biogas which is used to fuel engines. These engines drive generators that produce electricity whilst the heat created from the engine is diverted back to the digester to heat other biodegradable materials. This electricity is used by Thames Water on site so that less electricity needs to be bought from the National Grid.
Thames Water currently generates 15% of the electricity they consume through their sewage treatment AD plants. This figure already reflects the national target set by government to be reached by 2020. This also gives Thames Water an annual saving of £15 million off their electricity bill which results in, “downward pressure on customers’ bills”. Plans for a £250 million investment to increase renewable energy generation to 20% are already in place.
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