Waste to energy efficiency improvements: Integration with solar thermal energy.

Hybridisation of waste to energy with solar facility can take competing energy technologies and make them complementary. However, realising the benefits of solar integration requires careful consideration of the technical feasibility as well as the economic and environmental benefits of a proposed system. In this work, a solar-integrated waste-to-energy plant scheme is proposed and analysed from an energy, environmental and economic point of view. The new system integrates a traditional waste-to-energy plant with a concentrated solar power plant, by superheating the steam produced by the waste-to-energy flue gas boiler in the solar facility. The original waste-to-energy plant - that is, the base case before introducing the integration with concentrated solar power - has a thermal power input of 50 MW and operates with superheated steam at 40 bar and 400 °C; net power output is 10.7 MW, and the net energy efficiency is equal to 21.65%. By combining waste-to-energy plant with the solar facility, the power plant could provide higher net efficiency (from 1.4 to 3.7 p.p. higher), lower specific CO emissions (from 69 to 180 kg MWh lower) and lower levellised cost of electricity (from 13.4 to 42.3 EUR MWh lower) comparing with the standalone waste to energy case. The study shows that: (i) in the integrated case and for the increasing steam parameters energy, economic and ecological performances are improved; (ii) increasing the solar contribution could be an efficient way to improve the process and system performances. In general, we can conclude that concentrated solar-power technology holds significant promise for extending and developing the waste to energy systems.