Don’t Dismiss Thermal Energy Storage

Posted on December 4th, 2012 by

It’s a fact that’s hard to swallow. The United States not only over-produces energy, but it also wastes nearly 70 percent[1] of the energy it produces before it reaches its intended destination. But wait – how can we produce a surplus of electricity and still have enough demand to cause blackouts, grid failures and other infrastructural problems?

Unfortunately, it’s a sign of just how inefficient the current electric system is. Imagine trying to fill a swimming pool using 10 miles of hose with holes and kinks that lose water or slow it down before water ever reaches the pool. At one end, someone is manually pumping water from a well and at the other, after the water has traveled through the hose, the empty pool begins to fill. Power plants and the traditional energy infrastructure in the U.S. are somewhat similar.

Because power has to be generated and it has to travel such long distances through transmission and distribution lines and sub stations, most of the source fuel is lost at the plant and along the route through the form of heat and resistance. When 1,000 BTUs goes into a turbine, only about 300 BTUs are delivered for its intended purpose.

Just as the person pumping the water to fill the pool has to pump and produce excess water to compensate for what will be lost in the hose along the way, power plants are constantly operating to produce excess supply at all times to keep up for periods of high demand and to keep the grid reliable. Operators are not always able to change production quickly to meet demand. Instead, plants have to predict how much power will be used during a given time and then generate even more for proper reserves and reliability. The whole process seems a bit inefficient. More energy is wasted than is used and investments are made in assets that will have low usage or load factors. Can the system be improved?

Currently the system works because most of the source fuel used to generate electricity comes from fossil fuels and we have an abundance of generation.  As demand increases and some old dirty plants are retired the reserve is shrinking.  Some capacity is being replaced with renewable energy to meet state mandates; however, the storage benefit that comes naturally from fossil fuels is missing.  Renewable energy generation is not dispatchable. The wind may not blow and the sun might be covered by clouds or darkness. Renewable wind energy could be dispatchable. For example, the wind mainly blows at night. Using the proven technology of a thermal energy storage system could capture the nighttime wind energy for use in cooling during daytime peak demand periods.  The energy would be captured in the form to which it will be used eliminating a conversion.

Just as oil is stored in reserve tanks and coal is stockpiled on site and burned as needed, the key to less waste is creating energy during more efficient times of day and when renewable energy is available and storing it for use when demand is high or renewable energy is not available. It is almost always more efficient to take advantage of cooler night-time temperatures to create energy and store it than to create power instantaneously during summer peak demand periods.  HVAC loads are the largest contributor to summer peaks and it the easiest loads to shift off peak.

Widely used and often overlooked ice thermal energy storage systems have been steadily penetrating the building market and offering environmental and economical solutions for over 30 years. With on-site, grid connected Thermal Energy Storage (TES), there’s no need to transmit power across hundreds of miles during the heat of the day when the utility grid is straining to provide power. It’s like having your very own power plant. TES can also be fully integrated into a smart grid system, providing relief to burdened grids when demand is high. It minimizes the guessing game that power plants have been subjected to for decades. The energy is already there, a resource waiting to be tapped as needed in a world with less over-production and less waste.

While most people are aware that solar, wind, and water are capable of producing the energy that powers our civilization. The alliance of energy storage helps make these renewables more available and even dispatchable, to a degree. Indeed, the future of efficient energy in the United States depends highly on energy storage. Even in cases where utility companies are harnessing the wind to create power, that energy still needs a place to be stored at the risk of being lost. TES harnesses that wind power and saves it, ready to be called upon when building owners and operators need it most.

With over 8,000 installations around the world TES has remained a reliable, proven, competitive option for incorporating the power of an energy storage system onto the grid. Ice storage installations are becoming mainstream in major U.S. cities. For a smarter, more efficient future, it’s time to seriously consider thermal energy storage in addition to chemical and other forms of storage. “It is dramatically less expensive to store the cooling than the electron to make it.”2

The opinions expressed in this article are solely those of the author Paul Valenta, is Vice President of Sales and Marketing for CALMAC. For more information, visit


1 2 Mark MacCracken, CALMAC CEO and immediate past chair of USGBC., Our Choice, A Plan to Solve the Climate Crisis by Al Gore. page 293

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