Using renewable energy sources can reduce your dependence on the electrical grid. But the difficulty of predicting the ebb and flow of available power can make it hard to budget for electricity costs.
If your building is on target for net zero energy status, that calculation is all the more important because a day that’s hotter or colder than expected can drive up your energy consumption, which may not be fully covered by your on-site renewables.
Many new renewable energy installations incorporate energy storage systems from the start for this exact reason.
Energy storage systems can help with the production vs. consumption hurdle by storing energy in a battery, flywheel or other technology. That’s better than releasing it during peak consumption hours or when less grid electricity is available – for example, during a power outage.
Discover which energy storage system is best for you by starting with your energy bills. Know the sources of your costs, including any demand charges you’re paying and when your peak energy use occurred. You want to be able to shift your usage of your saved energy to overlap with your peak use.
“There are four key value drivers” behind the decision to invest in energy storage, explains Dan Svejnar, vice president and head of commercial for North America for Centrica Business Solutions. “Typically there’s an economic reason to do it, a potential resilience reason, an opportunity to resolve deferred maintenance issues or a sustainability angle. It’s about understanding which one of those buckets you fit into.”
Renewables and Energy Storage Systems
Energy storage systems can take several forms, according to the Department of Energy. The most common ones include:
These solutions rely on stored potential energy and include pumped-storage hydroelectricity, in which stored water is released through turbines to produce electric power and compressed air energy storage, which heats and expands highly pressurized air to drive a generator.
Flywheels, rotating mechanical devices that use their spinning force to drive turbine-like devices, convert their kinetic energy to electricity, according to the Energy Storage Association.
There are many types of batteries that can be utilized in building energy storage systems, from flow batteries like redox fuel cells, solid-state batteries like lithium ion products and hybrids like the lead-acid type most commonly associated with car batteries.
“In terms of energy storage, batteries are probably 90 to 95 percent of what you see out there as it relates to commercial buildings,” says John Merritt, director of applications engineering for Ideal Power, a power conversion company that offers solar power and energy storage together.
“The one you’ve probably heard of the most is lithium ion or a derivative of it. They have very high energy density, which means you can put a lot of battery into a building without it needing much space. A typical battery rack would be about the size of a Coke machine.”
There are two strategies for storing thermal energy.
Technologies like molten salt storage store the heat from concentrated solar power, then later convert it into superheated steam to power a conventional steam turbine.
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Others, like ice storage, simply eliminate one source of energy consumption by using grid electricity to make ice during periods when energy is cheap (namely, at night) and then use the ice as the source of cooling rather than the HVAC system’s compressor.
No matter the storage mechanism, solar energy is the most popular renewable energy source to pair with storage. That’s partially because solar power has become so affordable in recent years and partially because so many incentives are available.
“In California, the sweet spot is when you pair solar and energy storage. If you can demonstrate to the California Energy Commission’s liking that the energy you’re putting in the battery comes from the sun, not from the grid at night, you can get some pretty nice incentives on both the storage piece and the solar piece that you couldn’t get from storage or solar alone,” explains Merritt. “There’s a rush to combine the two.”
How Energy Storage Systems Save You Money
Pairing renewable energy with an energy storage system can save you money in many ways.
The most common is to allow your building to rely partially on stored energy during the part of the day when power from the electrical grid is most expensive. Don’t underestimate the avoided cost of downtime, though.
“If the grid goes down, solar does you no good at all because the solar system is not designed to provide backup power. Solar equipment alone can’t make a grid when the grid is absent,” Merritt says. “The majority of storage equipment that has been installed today can’t benefit the building when the grid goes down either. Backup power is an increasingly large part of the delivered value of a building.”
[Related: Smart Grid Initiative: Financial Benefits for Building Owners]
Fuel – like in your generator – has a finite life and if an outage lasts for a while, you run the risk of depleting your fuel. Installing an energy storage system can make fuel last longer and offers redundancy on backups for the most critical equipment, like lighting, computers, cash registers or gas pumps.
“You want to back up the critical circuits so that business can continue until the grid returns, and you want to be able to support the critical loads for some time,” Merritt explains. “Most outages are for hours and minutes, not days, so you can prevent the need for running a generator and avoid worrying about it not starting.”
Find Your Optimal Energy Storage System
Discover which energy storage system is best for you by starting with your energy bills.
Know the sources of your costs, including any demand charges you’re paying and when your peak energy use occurred. You want to be able to shift your usage of your saved energy to overlap with your peak use.
Merritt also recommends Energy Toolbase, a resource that analyzes your bills and your potential benefit from renewable energy and energy storage systems based on your billing data, utility and rate plan. If you’re not comfortable doing the initial analysis yourself, consider reaching out to an integration company that specializes in installing solar power and energy storage systems together.
One such provider, Geli, offers an online tool for designing energy storage projects and a project scorecard to help you prioritize projects based on economic outcomes.
Implementing smart storage strategies like these can make your renewables more reliable and positively impact your peace of mind and bottom line.
Research your options and make the decision that makes the most sense for your building, location and goals, then invest in reliability. The grid – and your budget – will thank you.
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