This article was published by The Energy Mix on April 4, 2024.
A new study out of Stanford University that tested combinations of hydropower, batteries, and green hydrogen as storage options for global grid stability pinpoints conventional hydropower as the lowest-cost pathway for Canada.
Canada needs neither batteries nor hydrogen fuel cells for grid electricity storage because of the country’s “immense hydropower output and abundant wind resources as well,” study author Mark Z. Jacobson, a Stanford engineering professor, told The Energy Mix.
“Hydropower is basically a big battery on its own,” he explained. “It can be used for either baseload power or to provide grid backup.”
For a country like the United States—plus several others—a combination of battery storage and hydrogen fuel cells can help make a low-cost, reliable transition to a 100 per cent clean energy grid, according to PV Magazine.
In most cases, the lowest system cost comes from a combination of the three: hydro, batteries, and hydrogen storage, the study found, after modelling and comparing the costs of power supply, storage, and demand response for 24 world regions covering 145 countries over three years.
Conventional hydropower with green hydrogen storage was never found to be the least-cost combination in any region.
But in four of the 24 regions, only conventional hydropower was needed.
Jacobson explained how that could play out in Canada. Citing International Energy Agency data, he said supplying all energy needs with wind, hydropower, and solar photovoltaics would reduce the country’s total energy demand by about 61.5 per cent. Some 22.7 per cent of that reduction would come from eliminating the energy needed to mine, refine, and transport fossil fuels and uranium, 6.1 per cent from energy efficiency improvements, and 32.8 per cent from the higher efficiency in replacing things like fossil-fuel powered cars and furnaces with their electric counterparts.
“The resulting energy for all purposes in Canada would be met primarily by onshore and offshore wind, solar PV in utility-scale plants and on rooftops, and existing hydropower,” Jacobson said. “The hydro would be the main electricity backup source,” while batteries and green hydrogen could be helpful but are not necessary.
Conventional hydropower with battery storage was the least-cost combination in five of the remaining 20 regions, where the ratio of required storage capacity to peak discharge rate is low. A combination of all three delivered the lowest cost in the other regions (the majority), where the ratio is usually high.
According to the study, the ratio determines whether green hydrogen storage helps lower cost, based on the ratio of battery storage capacity to the peak discharge rate and the way the costs and efficiencies of hydrogen compare to battery storage. Generally speaking, battery storage has the higher round-trip efficiency (the percentage of electricity put into storage that is later retrieved) and the lower cost of discharging energy, while green hydrogen storage has a lower storage capacity cost. When the amount of storage capacity is closer to peak discharge rate (a lower ratio), batteries are used for both peaking and storage. The batteries are therefore only storing energy for a shorter time period and, in these cases, green hydrogen’s lower efficiency and higher discharge costs only make a system more expensive.
But when the ratio is higher, the higher storage capacity cost of batteries can be offset by adding in some green hydrogen that can store energy at lower cost over longer time periods.
“In sum, when the ratio of the battery storage capacity to the actual peak discharge rate needed in a region is high, a combination of [battery storage] for most peak discharging and for some storage capacity, and [green hydrogen storage] for the remaining peak discharging and most storage capacity is beneficial,” finds the study. The ratio is higher in regions with low hydropower resources, weak wind or solar resources, or low peaks in demand.
The overall results “provide countries with concrete evidence and the confidence that 100 per cent clean, renewable grids not only lower costs but are also just as reliable as the current grid system,” Jacobson told PV Magazine.
He added that electrifying all energy sectors as much as possible is an important first step because globally, “the efficiency of electricity over combustion reduces energy demand by 38 per cent.”
Be the first to comment