A new study, Storage requirements and costs of shaping renewable energy toward grid decarbonization, published last week in the journal Joule by researchers at the Massachusetts Institute of Technology (MIT), finds that technologies with storage capacity costs below US$20/kWh will make them competitive and enable confidence in a 100% renewably supplied electricity system.
This represents a near 90% reduction in current costs of materials and manufacturing of battery-based energy storage systems (BESS), although the researchers say the target varies with the target output profile of different locations.
“It’s a large drop,” said senior author of the paper, Jessika Trancik, an associate professor of energy studies at MIT, in a statement accompanying publication of the paper, “but some technologies do tend to improve a lot as we’ve seen in the case of solar panels.”
Although costs and calculations in the paper relate to the demand and generation profiles of four US locations — Arizona, Iowa, Massachusetts and Texas — and their various energy markets, the broad outcomes and assumptions are of interest across a spectrum of energy jurisdictions.
Explaining the approach of the study, Trancik said, “Quantifying cost targets for energy storage required a new piece of insight about how patterns of the renewable energy supply, and fluctuations in this supply compare to electricity demand profiles.”
The infrequent but sometimes large shortage events in wind and solar generation “are critical in determining how much storage is needed for renewables to reliably meet demand,” says Trancik. This prompted the study authors to consider 20 years of data revealing disparities in demand and potential renewable supply, and the requirement for energy storage.
What if 5% of demand were met in another way?
The study found another factor could raise the target cost of energy storage to more like $150/kWh: That is, if required supply from wind and solar were reduced by just 5% and met by other sources, this would reduce the cost of required renewable electricity over a 20-year period by around half, allowing for more expensive storage options.
“The trick,” said Trancik, “is to figure out how to supply electricity for the remaining 5% of hours. This could potentially be accomplished with supplemental generation technologies, or perhaps demand-side management. The researchers also conclude that expanding the electricity transmission grid to transport energy and smooth variability between regions will help mitigate renewable energy-supply fluctuations.
Storage, says the paper, offers several advantages over other approaches to addressing the intermittency of renewables. In a statement that will resonate in the Australian context, the authors say storage may require fewer decision makers to agree on transmission expansion, and can be faster and more flexible in its implementation. Storage can also allow for larger quantities of energy to be time shifted when needed than demand-side management, and will likely achieve greater C02 reductions than using back-up generation such as gas turbines.
Where cost targets arrived at in previous studies have been for storage providing energy arbitrage in the electricity system (charging batteries from solar or wind when electricity prices are low for resale when demand and prices are higher), the new study focuses on a future supply system dominated by renewables.
“This work’s novel contribution is to estimate the costs of using wind and solar energy with storage to reliably supply various output profiles,” write the authors.
The solar, wind, battery nexus
Across the states examined, they found that the least-cost energy was generated by a combination of wind and solar — because of their complementary resource availability over time — working in tandem with storage. Researchers point out that while Arizona favoured solar in the mix, Texas leaned into the wind, and the other two states were balanced in their blend of energy resources.
One aspect of the study demonstrated how wind and solar plus storage could be used to provide baseload, intermediate and peak power outputs over a period of 20 years.
It found that, “To provide baseload, intermediate, bipeaker and peaker electricity at $0.10/kWh, with an optimal wind-solar mix, energy storage capacity costs must reach approximately $30–70/kWh, $30–90/kWh, $10–30/kWh, and $10–30/kWh, respectively,” (all values are in US dollars).
What’s in store?
The study also sought to identify the most suitable storage technologies for meeting the general target cost of US$20/kWh. It noted that pumped-hydro energy storage (PHES) and compressed air energy storage (CAES) have low capacity costs, but are limited by available topography offering suitable reservoirs or underground caverns, and their energy density is considerably lower than electrochemical storage.
Electrochemical energy storage systems, on the other hand, have much higher capacity costs, which are exacerbated by degradation over time, and the potential need to replace the storage system, which the paper notes could still make sense if the cost of the technology were extremely low.
“Scenarios in which renewable resources grow to meet a majority of society’s energy needs require finding ways to make a fluctuating renewable energy supply reliably meet demand,” concludes the paper. “Shaping renewables output to match the traditional grid roles of baseload, intermediate, and peaker plants is one possible solution.
“We find that achieving ultra-low storage energy capacity costs is one path for renewables plus storage to cost-competitively fill this role.”
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Your article highlights the missing link in alternative energy. Electrolysis cost reduction in hydrogen extraction and solving the psi cascading refueling heat miasma is also a solution begging for resolution.
Vanadium redox batteries solve most of these problems.
Scalability, instant charge discharge etc, vanadium is expensive but redt energy has started a lease program as the vanadium is fully recoverable after the batteries end life 20+ years, they have just installed one in England.
It kind of depends if you already have a gas turbine just sitting there (using fossil gas to balance power, as many people seem to do). If the gas turbine is what you usually use, then you already have the gas turbine.
This reduces the cost of conversion to hydrogen, and back again. However, the difficult part is pricing the electricity variably, so that when there is an extreme demand, power generators can sell this to the utility grid at a high price; but crucially – that the cost savings of reduced intermittency and infrastructure overcapacity are factored in to the cost of both the electricity itself (the slightly higher output price, which can be $60/MWh with an overall input price of $40/MWh) and the cost of hydrogen which is produced in periods of low demand and priced accordingly. This should achieve a cost of about $1/kg, or $9/mmbtu.
So we can see that depending how electricity is priced, both stable electricity output and low cost gas turbine power can be provided – knowing that hydrogen storage in volume is not expensive.
This methodology relies on a 50% average capacity factor, 25% annual utilisation rate of the electrolyser, and an electrolyser price of $500/kW.
I hope people start looking at hydrogen more, because often, you may not need a hydrogen price as low as this; perhaps for an industrial user, or for various transport applications.
Batteries are only suitable for short term storage and extremely expensive for long term storage.
In Germany they develop PtG with storage in deep earth cavities. That offers a cost effective solution for long periods without wind & solar (seasonal dips).
They have already >20 PtG pilot plants at MW scale running, and plan to start with regular rollout in 2024. As they may need it in 2030 when wind+solar will produce >50% of all electricity.
An pilot with storage: https://www.unternehmen-region.de/de/weltneuheit-kavernenspeicher-fuer-gruenen-wasserstoff-2463.html
The problem with saying that other sources can generate energy 5% of the time, is that the backup doesn’t have to just generate 5% of the power 100% of the time, it has to generate pretty much 100% of the power, 5% of the time. If it was 5% of the power it would be easy, for 100MW you would install 95MW of wind and solar and 5MW of backup (nuclear / fossil / hydro). But because it’s 5% of the time, it means you have to install 100MW of wind and solar and still close to 100MW of backups. You save fossil fuel when there is wind and solar, but you cannot close any of the traditional power plants. If you look at germany, there are times where their entire wind generation goes to 4% of installed capacity. When that happens they need the regular grid powering 96% of the demand. So what sounds like a 95% renewable mix on paper becomes in reality a 100% renewable + 100% non-renewable mix, at least in terms of installed capacity. For countries that are heavy on coal it is great for climate change to use some wind and solar some of the time to keep the coal only as backup, but is it really feasible to maintain two electricity grids in parallel. In the US there is a lot more land available compared to Europe, so there is probably more we can do there. But it looks like storage still has to become much cheaper before we can see a more meaningful transition, and especially the phase-out of traditional power plants.
This is right ,what you want to say through this article.But batteries are only suitable for short term storage and so costly for long term storage.
Batteries are only suitable for short term storage and extremely expensive for long term storage.
In Germany they develop PtG with storage in deep earth cavities. That offers a cost effective solution for long periods without wind & solar (seasonal dips).