Smart waste heat use in the future energy system in Finland

We introduce a general idea of how to estimate the possibilities of the utilisation of waste energies in the energy system, and we demonstrate the possibilities by simulating the Finnish energy system with alternative scenarios of renewable power and other production. Waste energies mean here such energy flows, which have wrong quality, timing or placement compared to the energy needs. They may result from e.g. the need for regulating thermal power (with ramping constraints), overproduction of wind or solar power and the non-flexible nuclear power. This situation already occurs in Central Europe, where the power system is not always able to utilise the wind and solar electricity available. In the Finnish case the existing and possibly newly built combined power and heat plants are potentially important in balancing the system, in addition to hydropower, and they play a central role here. Nordic countries have very ambitious targets concerning especially wind power. This means that on the Nordic market, there will be increasingly periods when there is a large amount of wind power available simultaneously in several countries. Finland is thus here considered an island with no transmission to the neighbouring countries. This minimises the risk of transferring the balancing problems to the other countries and e.g. overestimating the regulating possibilities of hydropower. Concerning the use of waste heat, we discuss the possibilities of not only demand side management, but also heat storages, replacement of direct fuel use for heat by other heating methods, biomass drying and even snow melting in cities for improved pedestrian safety and to avoid handling and space costs. We show that combining these can offer a system that can profitably absorb a high share of non-flexible power production and result in a heating system with very low CO₂ emissions, also supporting the CO₂ reduction of the rest of the energy system. The energy efficiency of a system must be judged in the right context concerning the energy quality, timing and the rest of the system. Flexibility of the system could be one indicator of energy efficiency.