Wind power is a rapidly growing source of renewable energy around the world. However, one of the challenges with wind power is that it can be intermittent – the wind doesn’t blow all the time. This means that energy supply from wind farms can fluctuate, making it difficult to integrate large amounts of wind power into the electricity grid. One potential solution to this problem is storing excess wind energy in batteries, which can then discharge electricity when wind generation is low. This article explores whether batteries are a viable option for storing wind power.
What are the benefits of storing wind power in batteries?
There are several potential advantages to using batteries to store excess wind energy:
- Smoothing out supply – Batteries can store electricity when wind generation exceeds demand, and discharge when wind drops, helping to balance out fluctuations.
- Avoiding curtailment – On very windy days, wind farms sometimes have to curtail (limit) power output to avoid overloading the grid. Batteries allow more of this clean energy to be captured and used.
- Shifting supply to peak demand – Stored wind energy in batteries can be discharged at times of peak electricity demand, when prices are highest.
- Enabling off-grid wind power – Batteries allow wind power to be used in remote locations away from the main grid.
- Providing grid services – Batteries can also provide services like frequency regulation to help stabilize the grid.
By helping to smooth out the variability of wind power and shift supply to match demand, batteries have the potential to enable much higher renewable energy penetrations.
What technologies are available for grid-scale battery storage?
Several battery technologies are emerging as viable options for grid-scale energy storage:
Lithium-ion batteries
Lithium-ion batteries have become the dominant technology for electric vehicles and small scale stationary storage. Their advantages include high roundtrip efficiency, high energy density, long cycle life and rapid response times. Tesla’s 100MW Hornsdale battery in Australia and LG Chem’s batteries paired with wind farms demonstrate their viability at grid scale. Costs continue to fall as manufacturing expands.
Flow batteries
Flow batteries store energy in external liquid electrolyte tanks, allowing for flexible battery size. They can have very long lifespans, with the electrolyte easily replaced. Vanadium flow batteries are currently the most mature technology, but research is ongoing into alternative chemistries like zinc-bromine. Startups such as ESS and Invinity are deploying grid-scale flow batteries.
Compressed air energy storage (CAES)
CAES stores energy by using electricity to compress air in underground reservoirs. To discharge, compressed air is expanded through a turbine. While less efficient than batteries, CAES can deliver very long output durations. There are two large-scale CAES plants in operation globally.
Other emerging technologies
There are a diverse range of other battery technologies at earlier stages of development, including sodium-sulfur, zinc-air, iron-chromium and organic flow batteries. Continued innovation and cost reductions are needed for these to compete with the more established technologies above.
What are the main technical challenges of using batteries to store wind energy?
While battery storage holds much promise, there are some key technical hurdles still to be overcome:
Energy density
The energy density of even leading battery technologies remains far lower than fossil fuels. Large areas of land are needed for grid-scale installations holding meaningful amounts of energy. Improving energy density will require ongoing materials research and development.
Lifespan
Most batteries have limited lifespans, varying from around 5-15 years with frequent cycling. Replacing expiring batteries represents an ongoing cost. Research to extend battery life and improve recycling is underway.
Roundtrip efficiency
There are always some conversion losses when charging and discharging a battery. Flow batteries can achieve roundtrip efficiencies of 75-80%, while lithium-ion batteries are typically around 90-95%. Improving efficiency reduces energy losses.
Output duration
The maximum length of battery discharge varies widely by technology. Most can only provide power for up to 10 hours, not the multi-day storage needed to cover longer lulls in wind generation. Longer duration options like flow and CAES batteries help address this.
Cost
Battery storage systems remain a major investment, despite falling costs. Ongoing manufacturing scale-up and technology improvements are needed to make batteries cost-competitive with peaking power plants and other flexibility options.
How much wind energy could feasibly be stored with batteries?
The amount of wind power that could realistically be stored with batteries depends on several factors:
- Cost – As battery costs fall, greater volumes become economically viable.
- Grid flexibility – Storage needs depend on the ability of the grid to balance supply/demand otherwise.
- Location – Batteries co-located at wind farms avoid grid power transfer losses.
- Duration needs – Storing larger shares of wind power requires longer battery output duration.
- Battery recycling – Reuse of battery materials reduces costs and mining requirements.
- Competing flexibility sources – Other options like demand response affect storage needs.
Studies have estimated the fraction of wind generation that could feasibly be stored with batteries to be anywhere from 10-50%, depending on these variables. With continued battery innovation and wind deployment, the upper end of these ranges may ultimately be achievable.
What are some examples of existing wind energy battery storage projects?
While most wind-battery storage is currently at pilot scale, some sizable projects are now in operation:
Hornsdale Power Reserve
The Hornsdale battery in Australia is one of the largest lithium-ion batteries in the world at 100MW/129MWh. It is charged using an adjacent 315MW wind farm and provides grid stability services.
Grand Ridge
NextEra Energy paired a 20MW/20MWh battery with the 202MW Grand Ridge wind farm in Illinois to test smoothing wind power output.
Golden Valley Electric Association
GVEA in Alaska operates a 4MW/16MWh battery storing power from a wind-diesel microgrid, reducing diesel usage.
Groton
Groton, Connecticut uses a 15MW/11.4MWh lithium-ion battery to manage the output of local wind and solar facilities.
As battery costs fall, co-location with wind farms is likely to accelerate. Battery storage also helps mitigate transmission constraints that can force wind curtailment.
Can grid-scale batteries eliminate the intermittency of wind power?
While batteries can help smooth short-term variability in wind generation, fully eliminating intermittency would require weeks of storage to cover the longest lulls. This is not feasible economically or technically today. However, batteries can still substantially increase use of existing wind power assets if applied correctly.
Complementing battery storage with other forms of flexibility – such as demand response, expanded transmission, and smarter grid controls – creates a more reliable system. The challenges of intermittency are also reduced by aggregating diverse wind resources from a broad geographic area.
So while batteries are not a silver bullet, they will play an important role in transforming the limitations of an intermittent resource like wind into a major asset providing reliable low-carbon energy.
What are the environmental impacts of grid-scale battery storage?
Deploying batteries to enable greater renewable energy penetration delivers clear environmental benefits by displacing fossil fuel use. However, some care must be taken to manage potential downsides:
Battery production impacts
Most batteries rely on mineral extraction, which can have habitat destruction and pollution risks. Responsible production and recycling is needed to minimize these impacts.
Toxic materials
Many batteries use hazardous materials like lead, cadmium and acid solutions. These must be handled carefully to avoid dangerous leaks and spills.
Recycling issues
If lithium-ion batteries are not recycled, toxic and rare materials are lost. Developing effective recycling processes is important for sustainability.
Lifecycle emissions
Battery production and recycling still entails some greenhouse gas emissions that partially offset gains during operation. Further improvements in manufacturing and recycling can reduce lifecycle emissions.
While not impact-free, evidence to date suggests battery storage delivers substantial decarbonization benefits when displacing fossil fuels and enabling renewable power.
How quickly could grid-scale battery storage for wind power expand?
The growth trajectory for batteries storing wind energy depends on a few key factors:
Production scaling
Massive factory investments by Tesla, LG, Samsung and others are rapidly expanding battery production capacity. This scaling is critical to achieve economies of scale and lower costs.
Technological improvements
Continued R&D to improve battery performance will enhance the value proposition for grid applications. Higher energy densities, longer cycle life and greater reliability will facilitate uptake.
Policy support
Favorable regulatory frameworks and incentives can accelerate wind-storage projects, as seen in some US states and countries like Australia. Streamlined approvals and grid interconnection processes also help.
Increased wind penetration
As the share of wind power on grids expands thanks to falling costs, so too does the need for smoothing and shifting this generation with storage.
Falling costs
Ultimately, expanding affordable battery manufacturing will be the key enabler for widespread storage of wind energy. Leading analysts predict lithium-ion costs will fall around 50% by 2030.
With these tailwinds, co-located wind-battery systems could grow from a few hundred MW today to tens of GW worldwide by the late 2020s. Realizing these projections requires policies to incentives storage’s multiple benefits.
What are the main alternatives to batteries for grid storage?
While batteries are attractive in many contexts, other technologies also provide large-scale energy storage:
Pumped hydro
Pumping water uphill into reservoirs then releasing it to generate electricity is by far the predominant grid storage option today, representing around 95% of capacity. Locations with the right topology provide enormous storage potential.
Compressed air
Storing compressed air in underground caverns provides long duration bulk storage, albeit with lower efficiency than batteries.
Thermal storage
Molten salt and chilled water tanks are inexpensive options for storing energy from concentrated solar power plants.
Hydrogen storage
Using excess renewable electricity to split water and produce hydrogen fuel provides unique long-term storage capabilities.
Flywheels
Spinning flywheels store kinetic energy for fast response grid ancillary services, but have relatively low capacity.
Depending on local conditions and grid needs, these alternatives may be more suitable than batteries in some scenarios. A mix of complementary storage options is likely ideal.
Conclusion
In summary, battery storage represents a promising solution to the problem of wind power variability, enabling greater use of plentiful renewable resources. While still relatively early in adoption, grid-scale batteries are poised for tremendous growth as costs decline. Realizing the full potential will require deploying batteries in smart, strategic ways that maximize their value to the grid. With well-designed policies and markets, battery storage can play a major role in building out high-penetration wind power worldwide and delivering deep decarbonization of energy systems.
