As the total electricity consumption in the US is projected to continue rising, innovative use of technology can more efficiently use the existing generation capacity to meet this increase in consumption without having to build additional power plants, by shifting the peak demand of electricity usage. In effect, level out the load curve by shifting the consumption of electricity from peak hours (i.e., during the day) to off-peak hours (i.e., during the night).
A large percentage of peak demand is generated by the summer time use of residential air conditioners. Residential air conditioning accounts for the largest percentage of total electricity consumed in the home, approximately 16.0%. During hot summer days, meeting the electricity demands from residential air conditioners can be problematic for utilities, which may be required to build additional power plants just ensure that the electricity demanded at peak hours during a couple of the hottest summer days can be met.
This is where the use of innovative technology, such as thermal energy storage, can shift the timing (peak hours to off-peak hours) of electricity usage from air conditioners and thereby reduce the need to expand generation capacity. A company called Ice Energy is attempting to do exactly that, by using ice. Ice Energy recently signed a contract with Southern California Public Power Authority to provide 53 MW of storage in the form of rooftop air conditioner units that use off-peak electricity to make ice that is then used during the day to provide the cooling. These units thereby reduce the electricity required during peak demand by relying on the ice instead of an electric compressor to cool the air.
The use of these types of thermal energy storage systems can be considered a type of distributed energy storage because they are located at the load instead of the source. This can have several advantages over a centralized power source (e.g., a gas peaking power plant) in that they require no additional infrastructure, no permitting or siting requirements, and they only require electricity that is already available.
As the US grabbles with how to satisfy increasing energy consumption, deal with potential climate legislation, and meet the rising cost of energy production (the current price for a 300MW coal-fired power plant is about $1 billion) the use of distributed energy storage systems could help address all of these challenges, at least partially.