Energy: ENEA presents new experimental infrastructure to generate heat for industrial processes from a solar source

NEA's solar "park" is expanding. On the occasion of the World Sun Day, celebrated every year on May 3, ENEA presented a new concentrating solar plant built at the ENEA Casaccia Research Center dedicated to the study, experimentation and validation of materials, technologies and innovative solutions to provide heat for industrial processes from a solar source. A modular and versatile technology, capable of ensuring a stable heat supply to industrial processes without the use of fossil sources. The plant adds to the vast solar field of the largest Research Center of the Agency and enriches the offer of infrastructures, instruments and technologies for the research and application development of concentrating solar plants, useful for research institutions and industries in the sector and in support of technology transfer.

The plant, which allows to test innovative materials and components in real operating conditions, is composed of a linear solar collector 36 m long, consisting of 425 mirrors (62.5x125 cm), for a total reflective surface of approximately 330 m². With a maximum operating temperature of 320 °C and a  200 kW  thermal power, the plant is now suitable to study small / medium sized industrial applications at a medium / high temperature (> 200 °C), which consume approximately 50% of the thermal energy required by industry, but for which, to date, there are no consolidated “green” technological solutions.

Among the potential sectors of application are those typical of the “Made in Italy”, including: cooking, pasteurization and sterilization in the food and beverage sector; bleaching and drying in textiles; bleaching and preparation of the pulp in the paper; distillation and evaporation in chemistry and pharmaceuticals; treatment for paints in the automotive sector but also some fundamental phases of industrial processes related to the production of steel, concrete, glass, plastic and leather.

"In Italy, the industry accounts for over 40% of the national demand for thermal energy and has a significant impact, both on global consumption and on carbon dioxide emissions, which international commitments and the Green New Deal require us to reduce, in line with the target of climate neutrality by 2050”, pointed out Walter Gaggioli, head of the ENEA Solar Thermal, Thermodynamic and Smart Network Division. "In this context, concentrated solar technology represents an important opportunity to produce heat, reduce the use of fossil fuels and promote the ecological transition thanks to a progressive decarbonisation of production processes."

According to international studies [1], approximately 90% of the thermal energy used by industrial processes worldwide comes from fossil sources (45% coal, 30% natural gas and 15% oil) and no more than 10% from renewables. About half of it concerns the so-called “hard-to-abate” sectors, i.e hard to electrify, for which concentrated solar power can provide effective solutions for decarbonisation.

Thanks to the use of thermal energy storage systems, this technology can also guarantee a reliable and flexible heat generation, adaptable to different industrial processes, to specific management and operating strategies, at different temperatures, thermal loads and plant sizes. The infrastructure, built by ENEA as part of the 2019-2021 Three-Year Implementation Plan for the Research of the National Electricity System (Program Agreement signed by ENEA-Ministry of Ecological Transition) is set up for future changes that will enable, through the use of innovative components and heat transfer fluids, to widen the range of operating temperatures and possible fields of application.

The PCS test plant (Solar Collector Test) is the first facility worldwide to experiment with molten salts as a heat transfer fluid in linear parabolic collectors. Built at the ENEA Casaccia Research Center in 2003 based on an original ENEA project, today is a key infrastructure for research and application development of molten salt concentrated solar plants.

The same technology is the basis of several solar plants around the world (for example in China, in Egypt as part of the MATS project) and in Italy in Sicily (Partanna plant). The system enables you to perform: operational tests in different operating conditions, checks on the performance and reliability of the components and analyses of critical situations and anomalies. The data obtained from the tests make it possible to build and validate calculation models, obtain the information necessary to design new components and systems, optimize management procedures, perfect new plant solutions, develop new types of high thermal energy storage and medium temperature. The PCS plant is also used for the qualification of commercial components and the training of technicians and young researchers, also at the international level.

The Dish, installed at the ENEA Casaccia Research Center, is a demo prototype of an innovative concentrated solar technology for distributed electricity generation. Its innovation lies in the integration of the circular parabolic concentrator (in technical jargon "dish") with a micro-turbine with automotive extraction air for small-scale electrical and thermal generation. The dish has a diameter of 12 meters and an area of 88 square meters entirely covered with solar mirrors that concentrates up to 2 thousand times the solar radiation in a small focal area, which in turn is converted into high temperature heat.

Compared to conventional photovoltaics, this system makes it possible to exploit the potential of thermal cogeneration for air conditioning in the civil and industrial sectors, and the desalination of water, using the residual heat of the air leaving the system. Furthermore, the technology is suitable for on-demand electrical / thermal generation, even in the absence of solar radiation, thanks to the possibility of accumulating heat and feeding the turbine with fuels or biofuels. The commercial target is distributed domestic or small business users (5-30 kWe) like small villages, small off-grid industrial users, while a modular approach is adopted for larger users.

A new thermal storage system based on waste materials  from steel industry to store thermal energy in thermodynamic solar systems. The aim is to replace a part of the molten salts used by the concentrating solar system to accumulate thermal energy at high temperatures (up to 550 ºC), with suitably reprocessed blast furnace waste, reducing the costs of thermal energy storage systems and recycling industrial waste otherwise destined for factory storage or landfill.

The Research Center of Trisaia (Matera) has an accredited laboratory that qualifies and certifies, in accordance with the technical regulations of the sector (EN 12975 and ISO 9806), components and solar thermal systems at low and medium temperatures, with consequent release of certifications to access state incentives provided for by current legislation. The laboratory conducts research in the field of solar thermal applications at low and medium temperature, technical-scientific support for the development of flat or concentrating prototypes for heat production, powering of thermal processes for civil and industrial applications and creation of innovative air conditioning systems. The activities concern in particular: analysis and energy optimization of low and medium temperature solar systems,  technical-economic evaluation and optimization of solar cooling systems, energy characterization of concentrating collectors for medium temperature applications .

Walter Gaggioli, ENEA - Head Solar Thermal, Thermodynamic and Smart Network Division
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[1] IEA e IRENA Data(2014)