What can electric companies do with the extra electricity they create? The question is a popular one in engineering, as many theories and practices have been developed over the years. Some of the techniques are more efficient than others, while the few highly efficient solutions tend to be very costly. Scientists have to weigh the benefits and costs of each method based on a region’s needs and available resources.
Electric companies in Houston, Texas, have come up with several appropriate, efficient ways to store excess energy and make sure that it is available for consumers who need it at a future date. The energy providers that Houston customers rely on for their daily energy needs are quite efficient when it comes to conserving surplus power and using it at a later date.
How It Happens
The dilemma for energy providers in Houston and other big cities is to generate the right amount of electrical power at any given time. Public demand for energy changes from day to day and season to season. For example, most consumers are aware that the demand for electricity rises significantly during summer months when air conditioners are running almost constantly in warm cities like Houston.
From an engineering perspective, it’s very difficult to create the exact amount of energy that a given location, like a city in Texas, might need on a specific day. Sometimes the energy provider creates more electricity than is needed. Rather than waste the power, it must be stored and saved for another day. There are several standard ways to save or hold, electricity until it is needed, batteries being the best-known of all methods.
But batteries are quite inefficient for holding large amounts of power for long periods of time, so scientists and researchers have come up with a few other strategies for banking the excess voltage that generating stations create. Unlike more tangible commodities, electricity is what scientists call “slippery,” or hard to preserve. If a farmer produces a bumper crop of corn or wheat, it’s easy to store it. For electricity, storage is not so easy. Electric companies in Houston and other parts of the U.S. work hard to find the most efficient techniques for storing excess voltage.
Eight Ways to Store Excess Electricity
Electric companies in Houston and elsewhere typically use one of the following eight methods for dealing with excess electrical power during periods of low demand.
- Hydro: This is currently one of the most popular ways to store extra energy. Using the excess amounts of electricity, water is raised from a low reservoir to a higher one. Later on, when demand for the power is greater, the water is simply allowed to flow downwards through a turbine that captures most of the original power that was stored.
- Car-to-Grid: Not yet widely used, this method does have great potential. Electric car batteries are used as mini-reservoirs of electrical charge at night when they are not in use. Later in the day, the excess voltage can be sent back to the grid. The downside of this method is that it requires lots of electric cars, the batteries which can run down with too much use.
- Rail Energy: Using the same principle as hydro storage, large rail cars full of heavy rocks or metal bars are transported up a hill with excess electricity. Later, that energy can be recaptured by allowing the car to roll down the hill and power a turbine. The downside of this technique is that it requires a wide-open space and rail lines.
- Thermal Storage: One of the cheapest, and oldest forms of energy storage, thermal techniques are ingenious in their operation. Excess power is used to freeze water that is placed on the tops of office buildings. When the electricity is needed, the ice is allowed to melt and cool refrigerator elements and provide cold air to offices. Of course, the method only works in summer, but it is an efficient way to “store” electrical power.
- CAES, Compressed Air Energy Storage: For more than 50 years, companies have been using this method effectively. Air is pumped, using the excess electricity, into a tight space like a mine or cavern. Later, that air can be released and used to drive a turbine that “gives back” most of the power that was required to condense it in the first place.
- Electrochemical Batteries: New advances in this area are promising. Lithium-ion and other chemical batteries have been around for centuries but can now hold a lot more electricity than before. One problem is that there are safety risks. Another challenge is that electrochemical batteries are extremely expensive.
- Flywheels: Using a complex principle of physics, excess energy can be stored for short periods in flywheels that spin in a nearly-frictionless environment. Because this method only works for about 15 minutes at a time, it’s not a good long-term solution but is highly efficient for short-term electricity storage.
- Flow Batteries: This method is similar to electrochemical batteries but the flow systems use fluid rather than solid chemicals to store the surplus electricity. Flow batteries are quite efficient and can hold vast amounts of power. However, there is a risk of pollution from leakage and an additional challenge in finding space for the massive storage tanks full of fluid.
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