Proceedings

Innovative flexible renewable electricity generators are essential in the development of decarbonized national power systems. The water industry can make a great contribution to the power network by flexibly generate electricity when needed by the grid. Additionally, an opportunity exists by supporting electricity generation with dynamic biogas production from Anaerobic Digestion (AD) of sewage sludge. Appropriate feeding schedules were calculated and tested in pilot and demonstration scale under high and medium loading condition, both in conventional AD and advanced AD, using Thermal Hydrolysis Process (THP) as pre-treatment.

Experimental results at pilot and demonstration scale establish the technical potential of AD as a provider of flexibility in the water industry. The results demonstrate that flexibilization capability exists for both conventional and advanced AD. Conventional digestion has lower capability and may require pre-defined feeding schedules to support electricity generation. On the contrary, flexible biogas production is an additional benefit that advanced AD provides, as biogas production rate shows a quick response. In all scenarios, the value of the biogas converted into electricity is higher than with a steady operational regime, increasing by 7.1% with THP. Feasibility of demand-driven biogas production is proven at demonstration scale. Full scale application could be limited by asset and extra capacity availability; however the process performance and stability are expected to improve.