Ways thermal storage can help the environment
May 5, 2016
According to the U.S. Climate Deputy, Rick Duke we're at a "global inflection point on energy markets and associated technologies like storage". Thermal energy storage specifically is a form of energy storage that has been around for decades and it does more than just help people stay cool and comfortable. This proven technology holds the ability to both advance renewables, which improves air quality, and to cut down peak electric demand to slow or defer generation and transmission infrastructure investment requirements while minimizing the operation of less efficient fossil fuel peaking power plants.
Here is how thermal energy storage works.
1. Reduces need for additional power plants
Air conditioning works by rejecting the heat of the building. To do so, it needs to draw a substantial amount of power. Up to 50% of a building's energy consumption is due to air-conditioning.
The problem with air-conditioning, other than the immense energy usage, is every building is running their cooling equipment at the same time in the middle of the day creating peaks in electrical usage - otherwise known as peak demand (kW).
"Thermal energy storage can reduce the emissions that accompany peak demand."
During these peak demand periods, the power grid brings on older, more environmentally damaging power plants to keep up with demand for air-conditioning so a blackout doesn't occur. These peaking plants are only used 2% of the year making their capacity utilization extremely low. As a result, the utilities charge hefty demand charges commensurate with peak electricity usage.
Thermal energy storage addresses the peak demand problem by storing cooling at night during off-peak hours when peak demand is low. By storing cooling off-peak, a building reduces peak demand dramatically.
Reduced peak demand not only reduces demand charges, but also helps to keep new power plants from being constructed and keep existing ones offline. Grid sited peaking plants are simply replaced with thermal energy storage in buildings. Consequently for every four buildings cooled by thermal energy storage, a fifth can be cooled without the need for additional power plants.
2. Allows for faster inclusion of renewable energy
While avoiding the use of coal fired power plants is critical for saving the environment, according to the U.S. EPA, society still relies on power to sustain modern life. As a result, retired power plants are being replaced with new renewable energy and natural gas plants.
The ultimate goal is to meet energy needs completely from renewable energy. One problem with adding renewable energy is that building new solar and wind plants are expensive. The high costs are passed on to consumers. What's worse is that we're not making the most efficient use of renewable power increasing costs further.
Renewable energy is dependent on the wind or the sun to produce energy so its output is intermittent. This results in low utilization. In 2015 utilization factors for solar were at 28% and 32% for wind compared to 92% for nuclear and 54% for coal, according to the U.S. Energy Information Administration (EIA). Utilization factors are the ratio of the plant's actual generation compared to its maximum potential generation.
When renewable generation is needed the most, it is available the least. It's called the "wind gap," which is defined as the difference between grid demand and wind output during summer on-peak hours (the sixteen hours during each weekday roughly corresponding to daylight hours).
As you can see in the graph below, demand and wind output for the summer on-peak period are shown relative to their average level across all hours of the year. Throughout 2011 in MISO, PJM, and ERCOT summer on-peak demand ranged from 24% to 42% higher than average demand during the year, while wind output was between 33% and 61% lower than its average during the year.
Therefore, renewable energy, by its nature, is vastly underutilized and cannot currently compete with fossil fuels. The reason for these low capacity factors is that solar and wind energy is only viable at certain times of the day such as when it's windy or sunny. This limits any buildings' plan to efficiently utilize renewable energy, until a way to store energy for when it's needed is employed.
Fortunately there are proven ways to store renewable energy and improve capacity factors. Thermal energy storage technologies store renewable energy in the form of ice to help smooth out electricity loads. This storage helps improve capacity factors by storing up to 50% of a building's energy consumption when renewable energy is plentiful and making that stored energy available when renewable resources are unavailable.
3. Helping the environment
The proliferation of thermal energy storage on a massive scale will help the environment by reducing the need for additional power plants, and will ultimately translate to a more environmentally-friendly power grid sooner by making renewable energy utilization more efficient and cost effective.
Just think, your buildings can single handedly have a more positive effect on the environment. By making renewable energy available when you need it, society is one step closer to a low carbon future.
