Abstract
In the transition to decarbonized energy systems, Power-to-Gas (PtG) processes have the potential to connect the existing markets for electricity and hydrogen. Specifically, reversible PtG systems can convert electricity to hydrogen at times of ample power supply, yet they can also operate in the reverse direction to deliver electricity during times when power is relatively scarce. Here we develop a model for determining when reversible PtG systems are economically viable. We apply the model to the current market environment in both Germany and Texas and find that the reversibility feature of unitized regenerative fuel cells (solid oxide) makes them already cost-competitive at current hydrogen prices, provided the fluctuations in electricity prices are as pronounced as currently observed in Texas. We further project that, due to their inherent flexibility, reversible PtG systems would remain economically viable at substantially lower hydrogen prices in the future, provided recent technological trends continue over the coming decade.
Highlights
The large-scale deployment of intermittent renewable energy sources, like wind and solar, has resulted in a growing challenge to balance energy demand and supply in real time1;2
Since our interest is in the economics of reversible PtG systems, we focus on such systems operating on their own as price takers in a wholesale market for electricity in which prices are determined hourly based on supply and demand
The economic trade-off is principally the same, except that the incremental cost and conversion rates may differ and instead assume the values wh, we, ηh(·), and ηe(·), respectively. Once they are at operating temperature, unitized regenerative fuel cells based on solid oxide cell (SOC) or proton exchange membrane (PEM) technology can rapidly switch between hydrogen and electricity production at full capacity22;27
Summary
The large-scale deployment of intermittent renewable energy sources, like wind and solar, has resulted in a growing challenge to balance energy demand and supply in real time1;2. Integrated PtG systems based on solid oxide cell (SOC) technology are shown to be competitive at current hydrogen prices, given sufficient variation in daily electricity prices, as is already encountered in the Texas market For such systems, it is efficient to mostly produce hydrogen and respond to sufficiently high electricity prices with electric power production. We project that if recent trends regarding the acquisition cost and conversion efficiency of solid oxide fuel cells continue, such reversible PtG systems will remain economically viable even in the presence of substantially lower hydrogen prices in the future This is because the inherent flexibility in these systems enables them to respond to lower hydrogen prices by operating more frequently in reverse mode, delivering additional electricity to the power markets
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