  An energy storage technology is valuable if it makes energy systems cheaper.
Traditional ways to improve storage technologies are to reduce their costs;
however, the cheapest energy storage is not always the most valuable in energy
systems. Modern techno-economical evaluation methods try to address the cost
and value situation but do not judge the competitiveness of multiple
technologies simultaneously. This paper introduces the market potential method
as a new complementary valuation method guiding innovation of multiple energy
storage. The market potential method derives the value of technologies by
examining common deployment signals from energy system model outputs in a
structured way. We apply and compare this method to cost evaluation approaches
in a renewables-based European power system model, covering diverse energy
storage technologies. We find that characteristics of high-cost hydrogen
storage can be more valuable than low-cost hydrogen storage. Additionally, we
show that modifying the freedom of storage sizing and component interactions
can make the energy system 10% cheaper and impact the value of technologies.
The results suggest looking beyond the pure cost reduction paradigm and focus
on developing technologies with suitable value approaches that can lead to
cheaper electricity systems in future.
