Reusing wasted heat to power industry
Transitioning away from fossil fuels is critical if Europe is to achieve its target of zero emissions by 2050(opens in new window). Wind and solar power now generate significant amounts of electricity, while coal production continues to decline. Nonetheless, more needs to be done. We currently waste around 70 %(opens in new window) of all produced energy as heat, which is simply lost into the atmosphere. This has a direct impact not only on the carbon footprint and costs of operation in energy-intensive industries, but also on thermal pollution in the local environment. Factories and industries can install waste heat recovery systems. For what is called low-grade heat waste, i.e. temperatures below 100 degrees Celsius, this tends to be economically unviable.
Using residual heat from manufacturing
This was the challenge that Swedish firm ZIGRID(opens in new window) set out to address. “One of our founders had a deep understanding of the issue of residual heat from manufacturing industries,” explains ZiGrid Technology project coordinator Lars Birging from ZIGRID. “After further research and visits to several other industries, we realised that wasted heat was a massive issue.” ZIGRID sought to find a way of efficiently harnessing this wasted energy for electricity production. The solution they developed uses residual heat from industry – at between 50 and 80 degrees – to heat and expand a gas. This then cools and shrinks again. “The power of this cyclical movement is harnessed through hydraulics, which drives a generator to create electricity,” says Birging. “What makes this technology unique is that it does not use turbines (and is thus more energy-efficient in low temperatures) and is capable of operating at temperatures as low as 50 degrees.”
Benefiting processing industries and data centres
The aim of the ZiGrid Technology project, which was supported by the European Innovation Council(opens in new window), was to scale up this technology to ensure market readiness. The company was also interested in better understanding the potential market for such an innovation. “The idea was to take us from conducting tests at customer sites to optimising and quality-assuring our product,” remarks Birging. For this, a technical team was formed to address technical scale-up issues. Different-sized configurations of the system were tested in real environments in the steel industry and benchmarked with hydrogen producers and paper and pulp industries. “At one of our pilot sites, we were forced to address more challenging temperatures than we had expected, but this helped with our development,” notes Birging. “In parallel, we identified key business applications that we wanted to address. This then fed back into the technical work, to ensure that our technology and business cases were aligned.”
Potential of heat-harvesting technology
The success of this work has helped to underline the potential of heat-harvesting technology. Birging and his team were also able to identify data centres – which generate huge amounts of heat – as a key potential end user. “These fit our solution very well, and have become our most strategic segment,” he adds. Moving forward, the focus now is on certification, scaling up production capacity and entering into agreements with potential clients such as hydrogen producers and data centres. “The efficient and clean use of energy already produced is a way in which we can help to meet agreed energy and climate targets,” says Birging.
