Everything You Need to Know About Energy Storage

Renewable energy sources like solar and wind are key to transitioning to a sustainable future. But the intermittent nature of these sources creates unique challenges. This is where energy storage comes in. With the ability to capture energy and deploy it when needed, storage technologies allow us to overcome renewable energy’s variability.

In this article, we’ll look at frequently asked questions around energy storage and troubleshooting common issues. By the end, you’ll have a deeper understanding of how these technologies work and their immense value. Let’s dive in!

Why Energy Storage Matters

First, it’s important to understand why energy storage is so valuable alongside renewables. There are three key reasons:

Storing excess renewable energy. When the sun is shining or wind is blowing, renewable systems sometimes generate more power than is immediately needed. Storage allows this excess energy to be captured instead of wasted. The stored energy can then be used later when renewable production falls.
Shifting energy supply to meet demand. Demand for energy is constantly fluctuating throughout the day. Storage enables renewable energy generated at off-peak times to be deployed during periods of high demand. This alignment of supply and demand is crucial for grid stability.
Providing grid services. Energy storage can provide valuable services to the grid, like frequency regulation and voltage support. These services help maintain reliability and resilience.

In short, storage acts like a battery for the grid. It’s a critical enabling technology for scaling up renewables and ensuring our energy needs are met 24/7. Global energy storage capacity is expected to grow from around 10 GW today to over 40 GW by 2025 [1]. Let’s look next at how these storage systems actually work.

How Energy Storage Systems Work

While there are many types of energy storage (which we’ll cover shortly), they all follow a similar process:

Charging: Excess renewable electricity or cheap off-peak grid power is used to charge the storage system.
Storing: Energy is retained in the storage medium until needed. This could be for minutes, hours, or even months.
Discharging: When electricity demand rises or renewable supply falls, the stored energy is discharged to the grid.
Recharging: The cycle then repeats as the storage system charges again.

So in essence, storage involves converting electricity into a storable form, holding it, then converting it back to electricity when required. This provides a reservoir of energy that can be tapped anytime – day or night, rain or shine. The most common storage methods use batteries, pumped hydro, compressed air, hydrogen, and thermal storage. Next we’ll look at the pros and cons of these options.

Types of Energy Storage

Lithium-Ion Batteries

Lithium-ion batteries have become the dominant grid storage technology thanks to their high efficiency (90-95%), low self-discharge, and falling costs [2]. They also provide very flexible siting options. However, their lifetime is limited to around 5-15 years. Prominent examples include the Tesla Megapack and LG Chem RESU.

Lead-Acid Batteries

One of the most mature and inexpensive battery technologies. Lead-acid batteries offer 65-75% efficiency and a lifetime of 5-15 years [3]. However, they have higher self-discharge and lower energy density than lithium-ion. Often used for small scale or backup power applications.

Flow Batteries

Flow batteries store energy in liquid electrolytes externally, allowing for flexible scaling of energy capacity and power output. They can be charged and discharged mostly without degradation, giving a 20+ year lifetime. But they have lower energy density than solid batteries and use expensive vanadium electrolyte.

Pumped Hydro Storage

A mature technology that accounts for around 95% of global energy storage [4]. Excess electricity is used to pump water uphill to an upper reservoir. When energy is needed, water is released through turbines to generate power. High capacity and efficiency, but options are geographically limited and projects can be slow and costly.

Compressed Air Energy Storage

Air is compressed and stored under pressure in underground caverns or pipes. On energy demand, the pressurized air is released to drive a turbine. A fairly inexpensive option if suitable geology exists nearby. But low energy density and low round-trip efficiency of around 50-70% [5].

Hydrogen Storage

Electricity is used to electrolyze water into hydrogen gas that can be stored in tanks or underground. The hydrogen is later converted back into electricity via fuel cells. Benefits include high energy density and unlimited storage duration. But overall system efficiency is currently low. Most hydrogen is produced from natural gas rather than renewables today.

Thermal Energy Storage

Excess electricity heats or cools a storage material so the accumulated thermal energy can be used later for heating/cooling needs. Relatively low cost, but geographic dependent and only suitable for certain applications. Can be daily storage or seasonal.

In summary, batteries offer the most versatility but have limited lifetimes. Pumped hydro provides long duration storage efficiently but requires specific terrain. The optimal solution depends on the scale, location, and application. Now let’s look at the benefits energy storage unlocks.

Benefits of Energy Storage

Energy storage confers multiple advantages to homeowners, businesses, and the electrical grid:

Savings: Storage reduces electricity costs by shifting usage to cheaper off-peak times and storing surplus renewable energy. McKinsey estimates $70 billion in potential annual consumer savings from storage in the US alone [6].
Resilience: Storage paired with rooftop solar provides emergency backup power during grid outages. This is increasingly valuable as climate disasters become more frequent.
Sustainability: Storage enables greater renewable energy penetration and reduces reliance on fossil fuels. It’s a pivotal tool for reducing greenhouse gas emissions.
Revenue: Storage owners can earn revenue by selling services like demand response and frequency regulation to the grid. These services also enhance grid reliability.
Power quality: Storage helps stabilize voltage and frequency levels on the local distribution grid, protecting sensitive equipment.

Thanks to these benefits, behind-the-meter energy storage attachment rate in the US is projected to rise from around 1% in 2020 to nearly 50% by 2035 [7]. Realizing this potential will require overcoming key challenges around cost and battery lifetimes – topics we will explore shortly. First though, let’s address some common questions that arise around energy storage systems.

Frequently Asked Questions

How much does energy storage cost?

Lithium-ion battery prices have declined nearly 90% over the last decade, from around $1,100/kWh in 2010 to $130/kWh in 2021 [8]. However, full installed system costs for large-scale storage are higher, typically ranging from $400-800/kWh today. The U.S. Department of Energy has set cost targets of $100/kWh for battery packs and $300/kWh for full systems by 2030 [9].

What is the return on investment for storage?

Payback periods for storage systems vary widely based on the application, electricity prices, incentives, and revenue streams. For commercial systems paired with solar, payback of 5-10 years is common. But in some markets returns can be achieved in under 3 years. Revenue from grid services can improve ROI.

How long will my energy storage last?

The lifetime of lithium-ion batteries ranges from 5-15 years before significant degradation depending on usage and operating conditions [10]. Some manufacturers guarantee 70-80% remaining capacity after 10 years. Other technologies like flow batteries can last 20 years or longer. Proper maintenance and operation within safe temperature/voltage ranges helps maximize battery life.

Can I install storage on my own?

Some small plug-and-play battery systems are designed for customer self-installation. However, given electrical safety risks and technical considerations, most homeowners prefer to have storage installed by experienced professionals. Any work should comply with local permits and building codes.

Are there special needs for siting or maintenance?

Proper ventilation, temperature control, and protection from weather/physical damage are key for optimal storage performance and safety. Lithium-ion batteries in particular can become unstable if overheated. Regular maintenance checks should be performed and some components may require periodic replacement.

Now that we’ve covered the basics, let’s turn to troubleshooting common issues that can arise with energy storage installations.

Troubleshooting Energy Storage Systems

While modern storage systems are generally reliable, problems can occasionally occur just like with any complex technology. Some typical troubleshooting scenarios include:

Reduced Storage Capacity

Potential Cause: Battery degradation due to age, heavy usage, or exposure to extreme temperatures. Internal faults or impurities within a battery cell.

Solution: First check the system monitoring platform for diagnostic details on the battery state of health and whether specific cells are underperforming. If faults are identified, battery replacement or cell swapping may be necessary. Also verify that the climate control system is functioning properly.

System Not Charging

Potential Cause: Disrupted connection between solar panels, inverter, and battery. Malfunctioning inverter or charge controller. Blown fuse. Battery management system error.

Solution: Check all connections and fuses. Inspect inverter and charge controller for faults or error signals. Reset battery management system. Contact installer if hardware replacement is needed.

Battery Not Discharging When Needed

Potential Cause: Discharged battery. Battery management system restricting discharge due to overheating or voltage/current limits. Home energy management system misconfiguration.

Solution: First check battery state of charge and temperature. Override discharge restrictions if safe and appropriate. Reconfigure home energy management settings as needed. Identify and address any system control failures causing abnormal operation.

Communication and Monitoring Failures

Potential Cause: Faulty sensors providing system performance data. Loose wiring connection. Software bug. Internet/network interruption at site.

Solution: Inspect sensor and wiring connections. Verify software is up to date. Reboot network hardware and confirm internet access is available. Check provider’s system status page for any service disruptions. Contact technical support if the problem persists.

Safety Hazards

Potential Cause: External damage to battery enclosure or internal cells. Signs of overheating. Smoke or unusual odors. Detection of gas leakage if hydrogen storage is used. Strange audible noises from system.

Solution: Immediately power down system and disconnect from energy sources if any safety issue is observed. Ensure area is ventilated and contact fire safety authorities if significant overheating or smoke has occurred. Follow precautions and contact qualified personnel for inspection before restarting system.

While we’ve covered a wide range of potential issues here, every situation is unique. Staff responsible for operations and maintenance should have proper training to diagnose and respond to problems. When in doubt, consulting the system installer, manufacturer and other technical experts is advised. This can minimize safety risks and prevent minor issues from escalating into major failures.

Looking Ahead

Energy storage remains a dynamic field with much room for continued innovation. However, it is already clear that storage is transforming the capabilities of renewable power. Market growth is accelerating globally as costs decline and supportive policies expand. Realizing energy storage’s immense potential will require holistic power grid planning and investment in complementary flexible resources like demand response. There also remain open research questions around topics like battery recyclability and second-life reuse.

While challenges persist, the overarching trend is clear – we are entering the energy storage era. The technologies outlined in this article will play an indispensable role in enabling the sustainable, reliable grid of the future. They provide one of our most potent tools for achieving a swift and just transition to renewable energy while meeting society’s growing electricity demands. We hope this overview has enhanced your understanding of how energy storage systems work and the critical services they provide. Please explore the rest of our site for more details on how innovative technologies like these are powering our clean energy future.

References

[1] International Renewable Energy Agency, “Electricity Storage Valuation Framework: Assessing system value and ensuring project viability,” 2020.
[2] U.S. Department of Energy, “Energy Storage System Safety: Technical Aspects and Best Practices,” 2020.
[3] Zhang et al, “Review of Existing Peer-Reviewed Lifecycle Analyses of Energy Storage Systems,” Energies, 2020.
[4] Electric Power Research Institute, “Electricity Energy Storage Technology Options,” 2010.
[5] OECD/IEA, “Electricity Storage and Renewables: Costs and Markets to 2030,” 2020.
[6] McKinsey & Company, “The value of energy storage,” 2020.
[7] Wood Mackenzie, “U.S. Energy Storage Monitor,” 2021.
[8] BloombergNEF, “Battery Pack Prices Fall to an Average of $132/kWh,” 2021.
[9] U.S. Department of Energy, “Energy Storage Grand Challenge Roadmap,” 2020.
[10] DNV GL, “Battery Performance and Lifetime: A Practical Guide,” 2019.