Compressed air energy storage (CAES) – Current state and future directions
A balance of supply and demand of electricity is essential to keep the grid supply running. With the advent of small-scale energy production units, especially renewable power and intermittent power supplies like solar and wind power systems, compressed air energy storage (CAES) systems are brought into the limelight to balance supply and demand in the electricity grid. Investments and innovations are being carried out in this field to make it more effective and on par with our demands.
Investors pouring money into CAES projects
As per the recent reports, the CAES market size is expected to grow at a CAGR of more than 42% over the period of 2020 to 2025. Looking at the growth and effectiveness of this technology, many big investors and governments are grabbing the opportunity.
Hydrostor, a Canadian company with their patented advanced compressed air energy storage (A-CAES) has received $250 million from the Sustainable Investing businesses within Goldman Sachs Asset Management. Hydrostor has designed their Advanced-CAES or A-CAES to provide long-duration storage of energy using proven components from mining and gas operations. Their scalable energy storage system can store energy from 5 hours to multiday storage wherever required. They have many A- CAES projects in the development phase that has capacities of around 200 MW each. The Goldman Sachs investment is aimed to support Hydrostor’s global expansion plans that also include the development of project pipelines and its marketing initiatives. The funding will be provided in installments bound to each of the Hydrostor’s project milestones.
Last year, Hydrostor received CA$4 million ($3.19 million) from the Canadian government through Sustainable Development Technology Canada and the Energy Innovation Program for the development of their Advanced Compressed Air Energy Storage (A-CAES) of 300-500 MW capacity in Ontario.
Likewise, the US Department of Energy in December 2010 has provided around $25 million to the firm Iberdrola USA for its 150 MW salt-based CAES plant that is being developed in Watkins Glen, New York.
Storelectric Ltd is also planning to build a 100% renewable energy pilot plant with 800 MWh storage capacity in UK which is going to be 20 times larger than any renewable CAES plant constructed till now.
Efforts to improve energy storage efficiency via chemical reactions
Thermochemical Energy Storage (TCES) is one of the recent research efforts ongoing to improve the efficiency of CAES systems. The reason for their interest in CAES technology is its low cost as compared to traditional batteries, though techno-economical analysis is still required to be performed by industry experts. Nonetheless, since the CAES technology seems promising to the scientists, their current endeavors involve recovering the thermochemical heat produced by facilities during the air compression process through the TCES technique.
The novel approach of TCES as published in the Energy Conversion and Management journal involves storing energy in chemical bonds as a recovery method of the heat produced during air compression. The process principle is based upon the redox reaction of a metal oxide like barium oxide. Under high partial pressures and resistance heating, the barium oxide is decomposed in the charging steps of CAES which transfers the compression heat into the chemical bonds of the reaction.
More research is still required in this area, but the proposed system ensures around 60% round-trip efficiency with a 20-hour storage time after charge which is greater as compared to the conventional CAES with around (40-50)% round-trip efficiency.
An innovative sea-version of CAES
Scientists have been researching on seawater versions of the Compressed Air Energy Systems. One such version arrives from the Dutch startup Ocean Grazer and was presented at CES 2022. The technology is also called the “Ocean Battery” technology with a “Bladder”. The technology is integrated with wind farms to solve the problem of intermittent production of wind power. The innovation received the “Best of the Innovation” award at CES 2022.
In the Ocean Battery technology, the excess energy is used to charge a bladder with seawater. During the high demand or when this excess stored energy is needed, the bladder will be inflated to run the turbine, generating electricity for use.
The major challenge that lies with the CAES plants is the management of thermal energy. As the highly compressed air gets heated, it decreases the operational efficiency of the plant. However, research is currently underway to tackle this problem and we’ve got success to a good extent. A lot of innovative technologies are being developed in the CAES space and a huge amount of investments is also pouring in – the recent one being the investment in the Hydrostor project by Goldman Sachs. All these aspects imply trust towards the CAES technology which ultimately is the sign of its effectiveness.
The future is definitely green and renewable energy production is inevitable. And, we’ll be seeing more and more CAES projects coming up in order to solve the problem of energy supply-demand imbalance that comes with the intermittent nature of renewable energy generation.