In Helsinki the energy company claims to reach 90% of overall efficiency with chp.
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They have also added "district cooling" where the cooling of houses produces heat for heating.

In Helsinki area they are building a new chp plant that burns household waste. When burning waste they get about 18-25% of the input energy (fuel) as electricity and 60-70% as heat. In another plant using natural gas they get 41% as electricity and 50% as heat. In the country there is more demand on electricity than heat, so when burning waste the smaller electricity production must be compensated. The overall efficiency of the whole energy sector is extremely difficult to describe, understand and optimise.