TU Delft researchers have proposed a new method for off-grid PV battery-electrolyzer-fuel cell systems in remote areas.
They argue that the system can be a suitable solution in rural areas where transmission and distribution networks are difficult to access.
“The proposed approach takes the load sizing coefficient as a key input parameter, it determines the extent to which hydrogen supplies the load demand in the winter time to match the seasonal imbalance,” the researchers stated, noting that the energy system is intended to serve an energy community consisting of several buildings. “In addition, a rule for choosing the right load factor to achieve specified goals, such as self-sufficiency.”
In the proposed system configuration, the electrolyzer is mostly used with the surplus power of solar electricity in the summer to produce hydrogen, which is then delivered to the compressor, stored in tanks, and used for electricity generation via fuel cells in the winter. However, it is not worth using all the surplus solar energy for hydrogen production, as it would increase the project’s fixed assets.
The innovative part of the system, the research group explained, is that it divides the winter load demand into two parts, one of which is covered by solar electricity and battery storage, while the other is covered by hydrogen in the production of solar electricity. is not available and the battery charge level is less than 40%.
“PV sizing follows the approach that the annual solar production corresponds to the annual load demand,” the researchers emphasized, adding that the battery size is strictly dependent on the days of autonomy of the energy system and the location of the project. “The PV production needed to produce hydrogen is determined by the efficiency of both the electrolyzer and the fuel cell.”
The Dutch group said the system should be sized so that the loss of load probability (LLP), which it defines as the ratio of the load demand that the energy system cannot cover in a year, divided by the total annual load demand, is always equal to zero. “The smaller the LLP, the more stable and reliable the energy system,” it further explained.
The academics carried out a series of simulations and found that the system can achieve levelized energy costs that are still higher than the price of energy in the Netherlands, although it also found that the integration of electrolyser and fuel cells with solar plus storage can increase the reliability and certainty of energy supply.
“However, as technology advances, the cost of hydrogen tanks and electrolysers is expected to decrease, increasing the affordability of this type of energy system,” they emphasized. “Furthermore, the efficiencies of the electrolysis devices and fuel cells also improve at the same time, which also increases the overall efficiency of the system.”
In the future, the researchers said they want to explore cheaper options other than a tank to store hydrogen and reduce the cost of the system. “In future work, it is worth investigating the use of heat to satisfy the heat needs of the end users, so that they also save on heat costs,” they stated.
They introduced a new method “An Approach to Sizing a PV Battery-Electrolyzer-Fuel Cell Energy System: A Case Study in a Field Laboratory”, published recently Estimates of renewable and sustainable energy.