Using Batteries as a Renewable Energy Source, Part 2

By Vernon Trollinger, March 21, 2017, Energy Efficiency, Green

Welcome to Exploring Renewable Energy Technology from Bounce Energy! Because the ERCOT portion of Texas can be thought of as a “walled garden,” renewable energy sources in Texas now make up a significant portion of the energy supply mix. It’s also a dynamic technology with new innovations, discoveries, and issues arising every week. Each month, we will examine the latest news in the industry to better understand what (if any) changes might come to the Texas energy supply.

Batteries Required —Part Two

If you’ve ever heard a discussion about renewable energy, you’ve probably heard someone retort, “What are you going to do when there’s no sun or the wind doesn’t blow?”

One answer is to use batteries. While last month we covered utility-scale cell-type metallic batteries, such as lithium ion and flow batteries, not all methods of storing energy look like batteries. This month, we’re going to look at some other ways of storing Texas energy that can be used to generate electricity.

Using Batteries as a Renewable Energy Source, Part 2 | Bounce Energy Blog

Pumped Storage — Currently, in terms of real estate, it’s the biggest energy-storing technology that’s capable of generating hundreds of megawatts (MW) of electricity. Very similar to a hydroelectric dam in that water flowing downhill spins a turbine to generate electricity. But instead of the water flowing away down a river, it collects in a retention pond or lake. At the end of the day when electricity rates fall, all the water is pumped back up to the top of the dam. There it waits until prices are high enough to for the water to be used again. There are two types of pumped storage; a closed loop system (such as the one described) and an open loop system that is connected to a naturally flowing body of water, such as a lake or river. Currently, Texas has no pumped storage projects, although the Lower Colorado River Authority operated one in the past between Inks Lake and Lake Buchanan. While the Texas State Energy Conservation Office points out the state’s hydropower capacities are small and probably face economic and environmental challenges, pumped storage could provide a valuable zero-carbon alternative to natural gas peaking plants.

Compressed Air Energy Storage (CAES)— Texas is littered with underground salt domes that have been turned into caverns for storing huge amounts of natural gas and oil. CAES works by using low cost late-night wind power to run giant air compressors to pump air into a salt cavern. The air is kept there under pressure until day time electricity prices are high enough to release the air to spin up turbines that generate electricity. Texas currently has two CAES projects. The first is APEX’s Bethel Energy Center about to begin construction at Tennessee Colony in Anderson County. The facility is planned to have a generation capacity of 317 MW and an air/energy storage capacity of 30,000 MWh. The plant is expected to be on-line by 2020. The second is Chamisa Energy’s proposed 270 MW facility in Swisher County, Texas.

Using Batteries as a Renewable Energy Source, Part 2 | Bounce Energy Blog

Flywheels— Flywheels have been around for almost two hundred years because they store energy by converting it into rotational energy. Once they are in motion, flywheels will stay in motion, and they keep all that stored energy. Once these were giant metal wheels that supplied smooth power to industrial mills, they were only able to safely spin at a few thousand RPMs. Modern flywheels are made of carbon fiber, housed in vacuums to reduce air-drag, and use magnetic bearings to achieve speeds in excess of 16,000+ RPMs. Fitted with electromagnets, they can be used as back-up power systems to generate electricity when the power to the motor that spins them is cut. They can achieve energy efficiency of up to 90%, consuming only 10% of the energy to spin them up to speed.

Because flywheels are able to provide consistently reliable speed over time, coupling in them to intermittent generation such as wind and solar helps smooth out voltage spikes and stabilize frequencies, keeping the electricity properly conditioned for grid-use. In Texas, three flywheel projects are storing approximately 5.6 MW. The the biggest is a 4.8 MW flywheel being used in Austin Energy’s new control center to provide additional power backup reliability.

Using Batteries as a Renewable Energy Source, Part 2 | Bounce Energy Blog

Thermal Energy Storage — The one thing Texas understands is summer heat and how important air conditioning is to keeping modern life livable. Unfortunately, summer air conditioning bills can go through the roof, especially for corporate headquarters. Around 25 years ago, JC Penny installed a thermal energy storage system in its 1.8 million square-feet corporate headquarters in Plano, Texas, to help cut back its energy usage. Installed by Calmac, the building’s cooling system is designed to make ice at night when electricity rates are lowest. The ice is then used to keep the building cool during the day. It makes LOTS of ice, 2.4 million pounds —but that’s equivalent to 4MW of cooling. Calmac has installed ice-cooling systems in 200 other locations in Texas. Retrofitting a large commercial building can provide a 33% ROI within 3 to 4 years.

In Austin, several companies, including the University of Texas and the City of Austin itself take advantage of thermal energy storage (including ice and chilled water) to reduce electricity demand. In Houston, the Texas Medical Center uses a monster 8.8 million gallon storage tank to supply eight hours of cooling for buildings and facilities on its campus.

Thermal Energy Storage is no longer limited to commercial/industrial projects. Last year, Ice Energy announced its Ice Bear 20 residential system that uses stored ice made during off-peak hours to provides up to four hours of cooling while using only 5% of the power.

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A native of Wyomissing Hills, PA, Vernon Trollinger studied writing and film at the University of Iowa, later earning his MA in writing there as well. Following a decade of digging in CRM archaeology, he now writes about green energy technology, home energy efficiency, DIY projects, the natural gas industry, and the electrical grid.

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