Capacity planning of wind-photovoltaic-electrolysis-battery system coupling renewable fuel synthesis

The wind-photovoltaic-electrolysis-battery (WPEB) system coupling fuel synthesis by supplying hydrogen and electricity simultaneously can reduce the carbon emission intensity of renewable fuels. However the capacity planning method is rarely reported, this work takes WPEB system coupling renewable methanol synthesis as an example. The business mode and the effect of load profile shape on the capacity configuration are first studied. Then, a two-stage capacity planning method is proposed to improve system performance: At the 1st stage, the capacity configuration is performed using 5 typical load profiles, and the case with minimum net present cost (NPC) is regarded as a pseudo-optimal solution. In the 2nd stage, the wind & solar power profile of the pseudo-optimal solution is standardized and the shape is used to build a variable renewable energy (VRE) flowing load profile as model input, the capacity planning result in the 2nd stage is regarded as the optimal case. The main conclusions are summarized below: (1) The WPEB system has five revenues from selling electricity, methanol, oxygen, CO2 trading in China certified emission reduction (CCER) market and carbon emission allowance (CEA) market. (2) Deep valley load profile obtains the lowest NPC of 2.7656 billion¥ and greatest internal rate of return (IRR) of 6.8843 % among 5 typical profiles. (3) The two-stage planning method can further decline the NPC to 2.2018 billion¥ and boost IRR to 10.5583 % by employing demand-side flexibility. (4) The sensitivity factors contributing to IRR orders from high to low are methanol price > O2 price > CO2 price of CCER > unmet H2 penalty > electricity price.