Energy systems are facing a great challenge to meet strict CO2 reduction targets. This goes hand in hand with the need to integrate massive amounts of renewable energy into the electrical power grid. However, the inherent stochastic and intermittent nature of renewable energy sources, such as wind and solar, make it increasingly difficult to balance electricity production and demand. To tackle these issues, the surplus electrical power from renewable energy sources can be converted to green hydrogen via water electrolysis. This can serve as a large-scale long-term (seasonal) energy storage method, facilitates stabilizing the future power grid with 100% penetration of renewable energy, and provides large industrial clusters with green hydrogen.
Such large-scale green hydrogen production, along with supplying off-shore wind production, needs to be smoothly integrated into the power system via advanced power conversion and grid technologies. To make green hydrogen technology more competitive, the Levelized Cost of Hydrogen (LCOH) must be reduced by a factor of 3~4. As one of the critical parts of a water electrolysis plant, the power electronic converters and the grid integration contribute to approximately 15%~20% of the total costs of the whole water electrolysis system for both alkaline and proton exchange membrane (PEM) water electrolysis technologies. Moreover, as the major power processor, the power electronic converters also have a great impact on the overall energy efficiency, especially considering the varying renewable sources as the power supply. Therefore, power electronics is a non-trivial cost-reduction driver for large-scale green hydrogen production through water electrolysis and for seamless grid integration.Challenges
In order to scale up the green hydrogen production, more efficient power conversion is required at a higher power rating and higher voltage level. Compared with state-of-the-art low-voltage (below 1 kV) power electronic technologies, the emerging medium voltage (MV) power electronics can perform significantly higher power conversion at improved efficiency, reduced volume, and reduced cost, thus enabling green hydrogen production via water electrolysis at multi GW level. However, to significantly reduce the LCOH and to make green hydrogen more competitive, more innovation needs to further reduce the capital cost (CAPEX) and operational cost (OPEX) of the power conversion system for water electrolysis.Objectives
The overall objective of this proposal is to explore the new circuits and the design rules to drive a significant cost-down of the medium voltage power electronics converter systems for large-scale hydrogen production through water electrolysis. The more specific objectives are given below:
- Explore new topologies for MV power electronics converters, resulting in high efficiency and cost reduction for large-scale water electrolysis.
- Explore new design rules to meet dielectric and galvanic isolation requirements and the flexibility required from the grid side and electrolyser side.
- Propose novel control options to fulfill the modularized control functionality, and to meet steady-state and dynamic control performance in large-scale water electrolysis.
The expected results of the PhD project will be as follows
- Novel cost-effective topologies for MV power electronics converters with modularity, scalability, and high efficiency.
- New optimization algorithm to fully explore the design space of MV power electronics converters and to identify the optimal design options.
- Novel modularized control of MV power electronics.
- Down-scaled experimental prototype for validation.