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A new battery for the Concentrated Solar technology

The CSP technology, one of the many solutions developed by Eni for its decarbonization strategy, can now count on an innovative thermal energy storage system.

by Mike Scott
15 June 2020
6 min read
byMike Scott
15 June 2020
6 min read

At the end of February, Eni CEO Claudio Descalzi outlined the company's long-term strategy for the next three decades, which set out how the business will become more sustainable and increase its focus on low carbon energy.
The plan, which has a target to cut the group's absolute lifecycle emissions by 80% over the next three decades, includes plans to progressively decrease production of oil reaching its peak in 2025 and to build more than 55 GW of renewable electric energy by 2050.
It will also increase production of biojet fuel, hydrogen and biomethane, and plans to build carbon capture and storage facilities to make its gas carbon neutral. Descalzi also announced plans to develop circular economy initiatives for producing hydrogen and methanol by recycling waste materials and from castor oil.
“The company's management has been thinking about decarbonization for quite a long time," says Francesca Ferrazza, senior vice president for Research & Technological Innovation, Decarbonization and Environmental Research and Development. “We have been doing a lot of research projects, but we have also been trying to apply this thinking to our existing businesses. The connection between research and our business units has become increasingly important."

The CSP project and the new storage system

One example is a new project in Sicily, where the company has recently opened a pilot plant for solar thermal or concentrated solar power (CSP) technology. Unlike photovoltaic (PV) solar panels, which create electricity directly from sunlight, CSP uses mirrors to concentrate the sunlight and heat a fluid that can be used to generate industrial steam or run a turbine and produce electricity.
The advantage of CSP is that, because the heat can be easily stored, it allows solar power to provide energy when the sun is not shining, on cloudy days and at night. “CSP works well but it is still a way behind PV and wind because it has not achieved the same economies of scale," Ferrazza says.
Most CSP systems use molten salts to store the heat, but Eni is testing an alternative approach. Developed by a Norwegian company called Energy Nest, this thermal energy storage technology uses a proprietary, concrete-type material to store heat that, it says, is cheaper to install and run than a molten salt system.
The system can store heat generated by fossil-fueled, nuclear and solar thermal power plants, as well as industrial facilities, and it can provide industrial heat, district heating or electricity. “We plan to fit the Energy Nest system into the CSP circuit, which is connected to an oil treatment plant that needs steam for the process" Ferrazza says. “This kind of thermal battery can be useful for other industrial applications, so we are also studying its potential to be used in gas-fired co-generation plants."


Eni’s CSP project

The new technology in detail

The technology has a number of advantages over other types of energy storage, says Energy Nest CEO Christian Thiel. “The key components are a steel frame the size of a 20-foot shipping container, which we have made in the Czech Republic and then shipped to the site where it is needed, and what we call Heatcrete. It's a high-performance concrete that is 75% quartz, while the other 25% is like the Coca-Cola recipe—a fiercely guarded trade secret."
The concrete can be made on site using existing infrastructure, reducing the costs and emissions associated with transporting heavy materials a long distance.
“Our main aim is to decarbonize industry," Thiel adds. "We can enable solar thermal projects to store their energy and we can also help our customers to turn waste heat into a primary energy source, which allows them to avoid the use of fossil fuels like diesel or natural gas."
Unlike lithium-ion batteries, which have to be replaced after a few years, “degradation is a non-topic for Energy Nest," continues Thiel. “Our projects have a lifetime of anything from 30 to 50 years. There's no chemical reaction involved, our facilities have no moving parts and the amount of thermal stress involved is minimal."
But Energy Nest doesn't see itself as being in competition with Li-ion batteries, he stresses. “Li-ion batteries are all about ultra-short-term frequency regulation, grid stability services and short duration storage, purely in an electricity context. We offer storage for a period of hours—we can charge for between four and 12 hours and discharge over the same period of time. In some cases, we will be complementary to Li-ion."
In addition, even though most of the focus in energy storage has been on storing electricity, the market for heat storage is more than three times the size of the electricity demand, representing a market of €300 billion to 2030.
Thermal batteries will have a crucial impact on decarbonizing industrial sectors such as chemicals, petrochemicals, food and beverages, textiles, metals and minerals, by allowing industries that are electrifying to cut emissions to store waste energy or cheap off-peak generation to be used later, cutting their power costs. They also make electrification a more viable option for companies with a range of heat energy requirements, and they enable businesses to use energy more efficiently by recovering waste heat, which cuts their fossil fuel consumption.

More to come

Energy Nest's other projects include a scheme for Austrian brickmaker Senftenbacher, which is reusing waste heat from a tunnel furnace to cut its use of gas and save 1,500-2,000 tonnes of CO2 emissions a year, and a Dutch open cycle gas turbine power plant which will use the stored heat to generate steam that can be used to generate electricity or industrial steam.
“We can help customers to substitute a large part of their fossil fuel use as part of the energy transition over the next 20 to 30 years," Thiel says.
Eni is also considering applying the technology to a gas power plant in Italy. “The technology obviously has wider applications than just CSP. It all comes down to the cost and reliability. It has to be profitable and it has to be something you can fit in to a commercial scheme," Ferrazza says. “If the technology works in these two very different cases—solar thermal and a conventional gas power plant—then it can work anywhere.

 

The author: Mike Scott

Journalist specializing in environment and business writing for corporate clients, newspapers, magazines and think tanks.