Cogeneration for a CO2-free city
About this good practice
The technology targets the global energy crisis and the challenge of global climate changes. The mechanical-biological unit is powered by sewer gas, produced by the treatment of anaerobically stabilized sludge, which is a by-product of wastewater treatment. While replacing fossil fuels for sustainable fuels, the technology exploits biogenic carbon, which would otherwise get released into the atmosphere without utilization. The Central Wastewater Treatment Plant receives wastewater from 98,7 % of the City of Ostrava (almost 300 thousand inhabitants, incl. food industry and coking plants) and has the potential capacity of covering up to 638,850 inhabitants. Thus, the cogeneration plant of Ostrava is ready both for adding the whole conurbation to its network, and for a clean, carbon-neutral development of the city. Cogeneration is a way, how to produce electricity and heat and, at the same time, how to reduce the carbon footprint. Ostrava decided for a sustainable energy policy by using renewable energy resources.
The cogeneration process is an integral part of the wastewater treatment. Costs cannot be particularly specified.
Evidence of success
Ostrava´s plant produced 2.7 mil. m3 of sewer gas, which was subsequently used to produce 5.1 mil. kWh of electricity. The manufactured electricity amount of 5.1 mil. kWh is equal to 43.6 % of the total energy consumption of the plant. In 2016, the facility treated 31.9 million m3 of waste water, incl. over 533,000 m3 of concentrated waste water from the coking and heating industries and 189,000 m3 of other concentrated waste water. A total 27,090 t of dewatered sludge was produced.
Potential for learning or transfer
The replacement of fossil fuel (natural gas) for renewable fuel (sewer gas) leads to an explanation of biogenic carbon. The biogenic carbon would otherwise get gradually released into the atmosphere without utilization. The cogeneration technology helps to transform Ostrava and its conurbation from a coalmining region into a CO2-free, dynamic society. The joint production of electricity and heat by the means of cogeneration is an up-to-date solution for post-industrial areas.