Running Hot And Cold
By Jack Burke06 June 2018
The new Electro-Thermal Energy Storage system (ETES) will store large-scale electricity, heat and cold for distribution to consumers, according to the companies.
ETES is designed to use surplus renewable-electricity to generate heat and cold for storage in insulated reservoirs during a so-called ‘charging cycle’. The heat and cold can be converted back into electrical energy on demand. According to the companies, it possible to distribute the stored cold and heat to different types of consumers. For instance, heat can be transferred to district heating, the food-processing industry, laundry facilities, whereas applications for the cold include cooling data centers, ice-hockey arenas or air-conditioning for skyscrapers. The system is location-independent and designed to suit various boundary conditions.
“The biggest challenge in building stable, climate-neutral energy systems is the intermittency of renewable energy in power generation and supply,” said Dr. Uwe Lauber, CEO of MAN. “To match an increasing consumer demand for energy with a fluctuating supply, the world needs reliable energy-storage systems.
“At MAN Diesel & Turbo we have made it our mission to drive the transition towards a carbon-neutral world. Together with our partner, ABB, we now offer a complete solution for the storage, use and distribution of electrical and thermal energy that is groundbreaking.”
Prof. Dr. Hans Gut, managing director of MAN Diesel & Turbo Schweiz AG, said ETES is the only storage system able to store electricity, heat and cold at the same time and also distribute them to consumers, which makes it unique.
“Due to the high overall efficiency, the modular character of the system and its low impact on the environment, ETES is a sustainable energy-storage solution that is suitable for a wide range of applications worldwide,” Gut said.
The turbomachinery technology and the process design of the charging and discharging cycle are the key elements of this energy-storage system and reflect MAN Diesel & Turbo’s core ccompetencies the company said. ETES includes MAN’s hermetically-sealed turbo compressor HOFIM, or High-Speed Oil-Free Integrated Motor-Compressor.
By eliminating components such as dry gas seals, lube oil system and gearbox, the HOFIM compressor package uses high-speed induction motor and active magnetic bearings (MECOS). The motor is cooled by process gas and directly coupled to the barrel type compressor.
In addition to gas storage and pipeline use, the HOFIM is also designated for dirty and/or sour untreated wellhead gas and can be used in other applications such as LNG, hydrogen and CO2.
In the ETES system, The HOFIM turbo-compressor runs on surplus energy from renewable resources, compressing CO2 in the cycle, which is heated to 120°C.
The CO2 is fed into a heat exchanger and heats the water. The hot water is stored in isolated tanks, each one at a separately-defined temperature level.
Still under high pressure, the CO2 is fed into an expander, which reduces the pressure – the CO2 is liquefied and cooled.
The liquefied CO2 is again pumped through a heat-exchange system, this time on the cold side of the system. Heat is taken from the surrounding water and ice is formed in the ice storage tank.