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World electricity consumption is expected to grow 60% from 2011 to 2030, being most of this new generation capacity attributed to intermittent renewable energy sources such as solar or wind. In this scenario there are two main challenges for the future: energy efficiency and energy storage. Researchers from UPM have developed thermophotovoltaic devices for the direct conversion of high temperature heat into electricity. Using these devices, SILSTORE develops turnkey solutions for waste heat recovery in high temperature industries (e.g. steel factories). Besides, SILSTORE is developing a patent-pending technology for ultra-high temperature energy storage able to provide extremely high energy densities, much higher than current existing technologies (e.g. batteries) at affordable prices.

Technology Solution

A thermophotovoltaic (TPV) device operates in the same way than a solar cell to transform the radiant heat emitted by incandescent bodies into electricity. The attractiveness of TPV if compared with conventional heat engines is that it does not require moving parts nor direct contact with the heat source, making it a simple and robust alternative to conventional heat engines for extremely high temperature operation. Furthermore, TPV is able to produce extremely high power densities, in the order of 100-500 times than that of a conventional solar cell. SILSTORE is using these devices for the waste heat recovery in high temperature industries, such as steel and glass factories. SILSTORE has also patented a technology for high temperature energy storage that uses TPV devices for energy conversion and molten silicon (at 1400C) as storage medium. This system has potential to reach higher energy densities than competing technologies (e.g. batteries) and uses abundant materials, such as silicon, the second most abundant element on earth crust.

“SILSTORE uses silicon as storage medium. Silicon is the second most abundant element on earth crust and allows reaching energy densities as high as 500 kWh/m3, well above the potential of most of the competing technologies”


Market demands

  • Waste heat recovery in industry
    • From 20 to 50% of the energy in industry is lost in the form of heat. This wasted heat represent annual losses of 10’s of M€ per factory.
    • Robust, simple and scalable systems are needed for waste heat recovery that do not interfere with the production process, and with payback times below 5 years.
  • Energy storage
    • Low cost technology: This is the main drawback of current storage technologies.
    • Use of abundant and safe materials.
    • Increase the energy density and efficiency.

Market potential

  • Globally, the advanced energy storage systems market that includes grid storage and transportation is expected to grow at a CAGR of 10% in from 2013 to reach over $10.8 billion by 2018. The key growth drivers include growing renewable implementation, new transmission and distribution grid construction and upgrades, smart grid installation, and growing demand for electric and hybrid vehicles [, 2013]
  • IMS Research report forecasts that the market for storing power generated by solar will soar from approximately $200 million in 2012 to $19 billion by 2017.
  • The demand in the global advanced energy storage systems market is expected to grow to 32,000 TWh by 2035, a 70% increase from 2012. The global consumption of electricity is expected to grow by over 60% from 2011 to 2030. This huge rise in demand has to be met by increased power generation which requires 6,000 GW of added new capacity, apart from the existing capacity [, 2013].
  • China, India, the European Union and the United States alone should invest at least USD 380 billion in new electricity storage capacity by 2050 to support decarbonisation [International Energy Agency report, 2014].


“In a steel factory, for instance, there exist large incandescent surfaces radiating heat 24 h the 365 days of a year. SILSTORE provides photovoltaic solutions to recover this heat and produce electricity on-site”


Competitive advantages

  • Waste heat recovery in industry
    • Simple, robust and scalable technology non-intrusive with the factory production process.
    • Ultra-high surface power density (>1 kW/m2)
  • Energy storage
    • Ultra-compact systems
    • Cogeneration (simultaneous production of heat and electricity)
    • Low cost and abundant materials.


“Thermophotovoltaic converters generate electricity from incandescent heat and produces extremely high power densities, in the order of 100 to 500 times than that of conventional solar cells”


  • IES-UPM is a cutting-edge R&D center in the field of photovoltaic solar energy, worldwide recognized.
  • Broad relationship with industry.

  • Patent pending in US: US 2015/0256119A1,  WO 2015/132305 A1.
  • Patent pending in Spain: 007-16



Development stage

  • Concept
  • R&D
  • Lab-Protoype
  • Industrial Prototype
  • Production


Alejandro Datas


Instituto de Energía Solar (IES-UPM)


UPM  contact

Innovation, Commercialization and Entrepreneurship Area

Centre of Support for Technological Innovation – UPM