Wind power plant and power-to-gas system coupled with natural gas grid infrastructure: Techno-economic optimization of operation

In this work, the coupled operation of a wind park and a hydrogen power-to-gas (P2G) technology is addressed in order to improve dispatchability and profitability of the wind resource. Among many available storage technologies currently under development, the P2G was chosen because of its large storage capacity and fast response. In particular, oppositely to traditional storage approaches, the solution that considers the direct injection of hydrogen in the natural gas grid infrastructure could reduce investment costs and improve the renewable fraction of fuels. Economic optimal operation and installed P2G power are calculated solving a mixed-integer linear programming (MILP) problem. Performances of the main component (electrolysis unit) are modeled, including additional costs for start-up and partial load operation losses. Technical limits on both electric and natural gas grids are also included. Some assumptions on the economic rules governing the electric grid unbalance are made, according to possible evolutions of the regulation framework focused on EU and Italian system. The simulation is performed on hourly basis, assuming realistic forecasted and real power production profiles from an actual mid-size (30 MW) wind power plant, together with prices of electricity markets and gas production. A sensitivity analysis is also performed varying both economic and technical parameters. Whereas in some scenarios the technology is profitable with the current investment costs, a reduction of electrolyzer costs down to expected mid-term targets would lead to a stronger competitiveness in each scenario. The study aims at identifying the influence of main technical and economic parameters on the effectiveness of the power-to-gas technology. Results show how the proposed solution allows better exploiting the wind resource, although the net electricity production can decrease due to the production of hydrogen, suggesting the possibility to substantially oversize the wind park in order to cover the same electric load.