As the world wakes up to the reality of the energy security challenge, intelligent heat pump technologies and district heating could be the answer we’re all looking for.
By Raymond C. Decorvet, Senior Account Executive, Global Business Development ETES, MAN Energy Solutions
The conflict in Ukraine and the ensuing energy crisis have shown the stark reality that energy security is, at its best, ephemeral when it relies on external resources. In response, coinciding with a growing sense of climate urgency, national governments are looking at massively increasing the share of home-grown green power in their energy mix.
According to the IEA’s Electricity Market Report 2023, renewables’ share of global power generation is forecast to rise from 29% to 35% by 2025. However, while this will lower carbon intensity and reduce energy dependence, it also represents a big challenge.
Renewables like wind and solar are intermittent. To successfully deploy them and still balance the grid requires large-scale storage. However, such storage must be able to deliver power instantly and simultaneously retain energy on a seasonal time frame so that, for example, summer solar capacity can be used to meet winter energy demand.
The solution to this complex issue is, in fact, deceptively simple – a heat pump system built around tried and tested compressor technology.
The heat pump solution
Electro-Thermal Energy Storage (ETES) is a unique bulk energy management technology developed by MAN Energy Solutions. Centered on a heat pump plus storage concept, it links electricity, heating, and cooling in a highly efficient reversible process. The core technology is the multi-stage HOFIM® turbo-compressor that, in this application, operates as a heat pump.
An ETES system progressively compresses and expands non-toxic CO2 to store or release energy from insulated water tanks. The simplicity of the energy storage is coupled with an incredibly robust and reliable industrial compressor that is already well-proven in the most extreme subsea oil and gas applications.
The current round-trip efficiency of ETES is of the order of 45%, with continued development expected to push that up to around 60% soon. However, unlike chemical batteries, the system efficiency and capacity remain constant throughout its 35-year design life.
In converting electricity into thermal energy and vice versa, the hot side may include up to four storage tanks, each at a different temperature, that can supply district or process heat, for example. Simultaneously, the cold side can supply rapidly growing markets such as data centers with significant cooling demand.
The ability of ETES to efficiently exchange energy forms also makes it ideally suited for sector coupling in which commercial, industrial, and residential energy needs have meshed. For instance, so-called waste heat from industry could be used to inject energy into the storage system for use as electricity by other consumers.
The ETES process can, of course, also be easily powered by renewable resources, with any excess renewable energy readily stored as either heat, cold, or both. When power demand is high, the system draws thermal energy from storage and converts it into electricity.
The system’s speed and flexibility mean it is ideally suited to serve both the short-term electricity spot markets and long-term seasonal storage. Thus, the ETES system can deliver ancillary services for the grid and capitalize on favorable conditions when they arise, offering significant arbitrage opportunities.
A real-time reality
As fantastic as this technological breakthrough sounds, its most straightforward configuration is already a reality. The Danish port city of Esbjerg is close to completing a 50 MW+ ETES system that will play a significant role in making the entire city carbon-free by 2030. Danish multi-utility company DIN Forsyning operates the city’s district heating network. It will use two large-scale ETES Heat Pump Units that will supply around 235,000 MWh of heat annually to 25,000 households.
The heat pump solution will replace a coal-fired plant and save up to 100,000 tons in CO2 emissions annually – the equivalent of the annual CO2 emissions of around 55,000 cars. The development marks a real advance in city-scale energy management.
Coupling the heat pump system with a district heating network also gives another level of flexibility as the heating system itself retains thermal inertia. In Esbjerg, for example, the network can fully meet customer demands with zero inputs for up to 10 hours. Esbjerg also has an existing 25,000 m3 hot water tank able to provide additional flexibility.
With the full-scale deployment of MAN’s solution now underway, heat pumps are proving that they can balance the diverse energy needs of a large modern city and succeed in a host of other applications besides. Meeting our needs for both energy security and net zero requires a radical rethink of our energy system, but we don’t necessarily have to reinvent the wheel.
Low-cost, easily scalable energy storage, and reliable, proven heat pumps are not a science fiction solution but a viable answer that can be deployed today.
For further information please contact: Raymond C. Decorvet, email@example.com