Author: Will Gorman Published: 5/20/2021 Utility Dive
The following is a contributed article by Will Gorman, graduate student researcher in the Electricity Markets and Policy Department at Lawrence Berkeley National Laboratory.
Developers are increasingly adding batteries to new renewable power projects, to make “hybrid” power plants that can deliver power more consistently, and at higher-value times.
While wind and solar resources are location-specific, batteries can go practically anywhere — including in pockets of the grid where storage adds a lot of value.
But our team at Berkeley Lab wanted to know which is better — putting batteries with the generator at hybrid plants or putting them where they deliver the highest value to the grid?
Generation + Storage
The rapid growth of solar and wind is having a growing effect on grid operations and on the value of wholesale power by time of day and location. California’s solar-driven “duck curve” is the most prominent example, as solar generation dominates the market during the day but fades as the sun goes down.
Developers are adding batteries to their solar projects to shift generation into the evening, to capture higher power prices during the “head of the duck.” Wind projects too can use batteries to smooth power output and avoid congestion.
In many cases the batteries are located with and integrated into the renewable power project, as a hybrid power plant. Wind and solar plants are located to take advantage of strong winds and sunshine, with plentiful land and good grid connections. But batteries can be put practically anywhere, like in high-value locations where they can provide additional values to the local grid, such as voltage support, congestion relief and resilience. With the right controls, they can also provide system-wide benefits, such as capacity and load following.
We wanted to know where batteries should be located to provide the highest value, and how are developers making the decision. Do hybrid renewable-plus-battery power plants provide more value than independently sited installations?
Using wholesale power market prices from 2012—2019 across the seven main U.S. independent system operators (ISOs), a new study compares the market value of hybrid projects to the value of the same generators and batteries deployed separately.
The study finds that adding four-hour duration batteries sized to 50% of the capacity of a wind or solar project raises the value by $3-$22/MWh depending on the year and region, with an average value of $10/MWh. The highest boost occurs in California ($15/MWh), where the value of adding storage to solar rises in tandem with increased solar penetration.
But an even higher value comes from siting the same batteries separately, in a nearby high-value location. This strategy results in higher value than co-located projects in nearly all markets and years, ranging from $2 – $50/MWh, with an average value boost of $12.50/MWh. The highest values are found in constrained regions, like New York’s Long Island, while lower values occur in Texas in certain years of the study period.