For someone who doesn’t work in the solar industry, I spend a lot of time talking about how amazing this technology has become. It’s easy to overlook the transformative potential of solar power beyond just electricity. In particular, the ability of solar energy to decarbonise industrial heat – a sector responsible for a significant portion of global carbon emissions – remains vastly underappreciated.

Heat is essential in manufacturing processes across industry, from brewing beer to producing pharmaceuticals. Traditionally, this heat has been generated using fossil fuels, resulting in substantial carbon emissions. Industrial heat accounts for 20–25% of global CO₂ emissions, making it a significant contributor to climate change.

Meanwhile, the growth of solar photovoltaic (PV) technology has been remarkable. Over the past decade, efficiency has significantly improved, production capacities have risen exponentially and the cost of solar panels has plummeted. Solar is now the cheapest source of electrical energy bar none. And we now have the experience to know that solar modules work effectively for many years, with only a slight degradation in performance over time. When you put in solar, you can have very high confidence that you will get clean power for decades.

Yet, after many years of strong growth, the solar roll-out is now being slowed by congestion on local electricity networks. The rapid increase in renewables has led to bottlenecks, where the grid cannot accommodate the additional electricity being produced remotely without slow and costly upgrades. This limits further solar and other renewable deployment, and prevents the full utilisation of existing solar assets.

Addressing this issue is crucial to continue the transition to renewable energy sources. Turning solar power into heat sidesteps these grid issues, as this does not require the grid. This is where emerging thermal storage technologies can help.

The ability of solar energy to decarbonise industrial heat – a sector responsible for a significant portion of global carbon emissions – remains vastly underappreciated.

How thermal storage works
Thermal storage systems capture the energy from solar PV panels and store it in materials that retain heat efficiently. At Caldera, our storage boilers have a solid core made of volcanic rock and recycled aluminium which can be heated up to 500°C with low-cost electricity and, thanks to our system’s advanced vacuum insulation, can be stored for days or even weeks. This heat can then be delivered as required, via a heat exchanger, as high temperature steam up to 250°C, to offer a reliable and consistent heat supply for a wide range of industrial processes.

This approach not only reduces dependence on fossil fuels but also offers protection against volatile energy prices. By stabilising energy costs, industry can achieve significant savings while reducing its carbon footprint.

Real world applications
At Caldera we have built a demonstrator at our Hampshire, UK, factory and are now in discussions with a number of early-adopter industrial users in sectors including pharmaceuticals, brewing, textiles, food processing and distilling – all of which require substantial amounts of heat for their processes.

Each of our storage boilers can store up to 4 MWh of low-carbon thermal energy. To put this in perspective, over the course of a year that’s enough energy to brew 8 million bottles of beer. A typical brewery would run 24 hours a day, so the storage system would charge during the day from solar to enable carbon-free brewing overnight.

Multiple units can be combined to store and deliver hundreds of megawatt hours, and by integrating solar PV with thermal storage, users can supplement or replace their gas boilers, significantly reducing their carbon emissions.

Overcoming challenges
However, despite the clear benefits, several challenges must be addressed to accelerate the adoption of thermal storage technology. One significant barrier is the conservative nature of many in industry. Companies are often hesitant to adopt new technologies without seeing them successfully implemented elsewhere. Early adopters and demonstration projects play a vital role in showcasing the efficacy and reliability of these systems. That is why Caldera has a demonstration system running at our own site.

Another challenge is the integration of thermal storage systems with existing infrastructure. However, modularity in design allows for flexible solutions tailored to specific industrial needs. Where solar sources are limited, hybrid systems help industry decarbonise up to the limit of the available renewables. By working closely with industry partners, hurdles can be overcome, paving the way for broader adoption.

While solar power’s role in generating electricity is well-recognised, its potential to revolutionise industrial heat should not be underestimated. By harnessing the sun’s energy and leveraging advanced thermal storage technologies, we can begin to decarbonise one of the most challenging sectors and take a significant step towards a sustainable future.

The views and opinions expressed in this article are strictly those of the author only and are not necessarily given or endorsed by or on behalf of the Energy Institute.

• Further reading: ‘Hot rocks could increase duration of thermal storage solutions’. Thermal energy storage can play a key role in decarbonising hard-to-abate industry sectors – those that, typically, depend upon high temperature heat. New Energy World Features Editor Brian Davis looks at its potential.
• Find out how thermal storage technology can help solve heavy industry’s emissions problem, while also enhancing security of supply and reducing costs.