On June 30, 2016, the first STEM® (Solar Thermo Electric Magaldi) industrial model plant started operations in San Filippo del Mela (Sicily).
Installed in the Integrated Energy Pole of the A2A Group – the largest Italian multi-utility in the energy sector – this innovative CSP technology is the first one worldwide using sand as thermal energy storage.
STEM® technology has been developed and patented by Magaldi Group in cooperation with the Federico II University of Naples and some prestigious institutes of the National Research Council (IRC, INO, ISTEC).
Founded in 1929, Magaldi Group is the world’s leading specialist in dependable and environmentally friendly bulk and abrasive material handling systems, pioneering solutions for demanding problems in solid-fuel Power Plants, Metallurgical & Mining companies, Renewables Energy fields.
Over the years, Magaldi has developed a broad range of patented technologies able to ensure benefits like high dependability, longer service life, negligible maintenance, water and energy savings, as in the case of STEM® technology.
This new CSP system represents a so called “disruptive” technology because it’s able to collect solar energy – through a solar field made of heliostats – and convert it into thermal energy to be used immediately or stored and extracted when desired.
STEM® is based on modular units rated 2 MWth each, that can be combined together to produce the required steam flow rate, to be used to generate electricity or heat, in case of cogeneration.
Each module is able to generate superheated high-pressure steam at 520°C, to match the dedicated thermodynamic cycle, with 6 hours thermal storage at nominal load. Storage hours will increase accordingly if less power is required.
Solar radiation captured by approx. 800 heliostats is concentrated on a secondary reflector (beam down) and subsequently focused in a receiver positioned at ground level.
The receiver is based on a fluidized bed technology, which provides both thermal storage and steam generation.
This ability makes STEM® particularly suitable to cover the energy needs in remote sites without grid connection, allowing the required energy coverage throughout the day.
The great availability of the heat storage and the flexibility of production makes it possible to cover energy needs such as desalination of water, air conditioning and production of industrial steam, thus sustaining the economic and social growth of isolated areas.
Compared to existing CSP technologies, STEM® introduces two main innovative elements. First of all, the modularity (it’s to say the combination of a variable number of solar generation units) allows to realize generation systems of different configuration, power and capability (min. 500 kWe – max. 20 MWe). A typical 21,5 MWth plant requires 10 modules. Additional modules can be installed at a later stage, shall the power demand increase. But the main innovation is its ability to store the solar energy and deliver it when needed, even at night or in cloudy periods.
Moreover, the absolute absence of emissions into the environment (both in case of normal operation or failures) as well as the non-use of cooling water and any chemicals, makes STEM® technology the best way to produce green energy in remote zones.
Even from the standpoint of the landscape plan, STEM® system confirms its commitment towards the enviroment. In fact, compared to traditional Power Tower systems, STEM® does not have a huge visual impact since its highest structure does not exceed the height of 27 m meanwhile other CSP tower systems reach over 100 m.
STEM® key strengths:
- Reliability: The simple operational process and the modular configuration give STEM® a competitive advantage over other CSP technologies. Even if one module is under maintenance, the other modules guarantee continuity to the production of steam.
- Flexibility: Fluidized bed technology using sand as storage medium and the possibility to connect the modules in parallel or in series enable the system to generate electricity according to the demand load.
- Modularity: The base modules can be combined together to meet the required power demand. It is possible to add modules at a later stage, in case demand increases.
- Hybridization: STEM® technology can be integrated with both renewable and fossil fuel plants, to guarantee a continuous operation, day and night, year-round. The receiver is designed to also allow the combustion of low heating value fuels, such as biogas.
- Cogeneration: High temperature steam generated by can be used in several industrial applications such as district heating and cooling, water desalinization, agricultural greenhouses.
- Environmentally friendliness: STEM® technology only uses absolute eco-friendly materials: glass for heliostats, steel for structures and sand for thermal storage, so that, even in case of decommissioning or at the end of its working life, all materials are completely recyclable.
STEM® technology has already won endorsement from international leaders in environment and renewable energy from around the world:
Hon Mike Rann AC CNZM, Premier of South Australia 2002-2011, former Minister for Sustainability and Climate Change and Economic Development:
“Now that STEM® has moved from prototype to commercial application, it is clear that this is a breakthrough, scalable renewable energy technology that deserves the closest examination. For me, STEM® is a real advance on other forms of CSP, particularly in terms of storage. It doesn’t need batteries and can keep generating electricity on an industrial scale at night as well as during the day. As with other technological advances STEM’s great strength is its simplicity. It produces energy more cleanly, more cheaply, more efficiently and with lower maintenance. I was first attracted to Magaldi’s STEM® because of its potential for rural and remote “outback” communities, mines and mining camps around Australia that are not connected to the electricity grid and currently rely on expensive and polluting diesel. I am sure STEM’s application will, of course, be much wider. There is already interest from India and Southern Europe and its potential for Africa and the Americas is massive. I am proud to be associated with Magaldi’s STEM® and encourage its examination for a range of off-grid applications.”
Professor Tim Flannery, Chief Councillor Climate Council, Australian of the Year 2007:
“The commissioning of Magaldi Industry’s first commercial-scale STEM® solar thermoelectric power plant marks a major milestone in the global shift to renewable energy. Able to generate electricity even when the sun is down, STEM® represents a fundamental breakthrough. Utilising only steel and silica in its construction, it is simple to operate and maintain, and provides industrial scale generation without the use of batteries in scaleable, half-megawatt units, STEM® is perfectly adapted for powering towns and small cities in the developing world. But because it also generates heat, it is ideally suited for use in the fast-growing greenhouse sector, and as an energy provider for many industrial processes. As an Australian, I’m tremendously excited at the prospect of an innovation with the potential to generate cheap and abundant energy and fresh water using only sunlight.”
R.K. Pachauri, Former Chairman, Intergovernmental Panel on Climate Change (IPCC), and Former Chairman, The Energy and Resources Institute (TERI). Nobel Prize for peace 2007:
“Solar thermal technology has been an area of major research and development with enormous promise. In this regard, the STEM® technology developed by the Magaldi Group is a revolutionary development, because not only does it provide an effective means for storage and utilization of energy for long periods, but it is able to do so with the use of silica sand, which is simple, cost effective and eliminates the use of chemicals and toxic materials. I have no hesitation in stating that the STEM® technology provides a unique opportunity to produce energy without emissions of greenhouse gases, and carbon dioxide in particular, but it also opens up opportunities for decentralized and distributed generation in many parts of the world, where energy access is a serious problem. I would expect that STEM® will find widespread application in a number of industrial applications, in rural areas in the developing world and for power supply to the grid across the globe. This technology would be an effective means for mitigation of emissions of greenhouse gases and for providing energy in fulfillment of the 7th among the 17 Sustainable Development Goals adopted by the UN General Assembly.”