Large Combined Heat and Power Plants for Sustainable Energy System

An energy supply based on 100% renewable energy in Denmark is the official goal for the Danish energy policy towards 2050. A smart energy system should be developed to integrate as much supply from fluctuating renewable sources and to utilise the scarce biomass resources as efficiently as possible. CHP (combined heat and power) plants in Denmark will change their role from base load production to balancing the fluctuation in renewable energy supply, such as wind power and at the same time they have to change to renewable energy sources. Some solutions are already being planned by utilities in Denmark; conversion of pulverised fuel plants from coal to wood pellets and a circulating fluidised bed (CFB) plant for wood chips. From scientific research projects another solution is suggested as the most feasible; the combined cycle gas turbine (CCGT) plant. In this study a four scenarios are constructed to analyse how the different alternatives influences the energy system. The scenarios are analysed in the energy systems modelling tool EnergyPLAN both from a technical energy systems perspective and from a market economic analysis with focus on the electricity exchange potential of the scenarios. The scenarios are assessed on their total socioeconomic costs and the biomass consumption. The CCGT CHP plant is concluded to be the most feasible of the assessed types considering both a technical analysis and a market economic analysis with electricity exchange. It is also concluded that the current economic framework for large CHP plants generates a mismatch between socioeconomy and business economy as well as an unsustainable level of biomass consumption and it is recommended to revise the regulatory framework.