Techno-economic evaluation of bio-CLC: Assessing the Nordic policy situation

Negative emissions have been considered necessary in order to limit the temperature increase to 1.5°C as set in the Paris Agreement. Bioenergy combined with carbon capture and storage (BECCS) offers an attractive way to generate these negative emissions while simultaneously providing energy. One of such technologies is chemical-looping combustion of biomass (bio-CLC), which has been considered to economically outperform its alternatives such as oxy-fuel combustion. The Nordic district heating networks provide a suitable investment environment for CLC: the combined heat and power (CHP) plants already utilize large shares of biomass, which is only to be increased due to expected changes in legislation such as phasing out coal. The paper has two key objectives: to discuss and evaluate policies to further boost the development of BECCS, and to evaluate the feasibility of CLC installation in two alternate CHP plants under both the existing and introduced policies. The techno-economic evaluation is carried out in a generic Nordic district heating system in varied market scenarios using a cost-optimization model based on mixed-integer linear programming (MILP). As the main results, the existing policy framework (EU ETS) and an additional carbon tax were found insufficient to achieve positive net profit for the CLC investment. Adding an incentive for the negative emissions while generating heat or power was discussed be complex, with the latter also appearing ineffective due to relatively low district heat demand in the studied system. The investment was found to be feasible in a scenario in which the negative emissions were subsidized at 50 €/ton, while compensating CO2 transport and storage costs for the plant owner nearly led to positive net profit. The former option can be considered to be simpler to implement to the existing legislation, while the latter would potentially have a smaller risk to lead to excess utilization of biomass resources.