Cubit Power Systems Inc., based in Ottawa, Ontario, Canada, is a turnkey developer of renewable and clean power projects in the United States and Canada. It is also the developer of a latent heat storage system for utility-scale solar thermal power plants.
Cubit has grown from the ground up by providing end-to-end services in renewable energy for commercial, municipal and agricultural clients. The company has worked on photovoltaic installations, biomass projects, and combined heat and power systems, all the while developing its unique thermal energy storage technology.
Thermal storage has increasingly been incorporated into solar thermal plants, with a couple of very large plants coming online in just the past six months. These plants use molten salt technology for storage. The Solana power plant in Arizona, for example, makes use of twelve 12,000-ton tanks of a sodium nitrate/potassium nitrate mixture that permit the plant to operate for about six hours after the sun has set.
Cubit’s patent-pending technology makes use of phase change materials and the inherent latent heat of the phase change to store heat in a far more efficient fashion. Their technology provides a single-tank solution with significantly lower capital costs, far less storage medium, a much smaller footprint, and less infrastructure than the current technology. The heat storage medium is essentially a slurry in which the phase change material are solids suspended in a liquid. The system absorbs heat by melting and releases it when it resolidifies.
The technology can work with a variety of phase change materials, which permits a large range of operating temperatures ((~140°C-500°C.) The far greater energy density of the latent heat system means that in principle Cubit’s technology can provide a 24-hour operating cycle for solar thermal plants. The latent heat storage system can accept heat from a variety of heat sources other than solar thermal plants. It could be used in a variety of power plants that are based on heat engines.
In developing its latent heat energy storage technology Cubit has solved a variety of technical problems including optimizing heat transfer when it is dominated by the thermal conductivity of the solid phase change material and obtaining acceptable heat transfer rates from solar collector into the solid phase change materials.
In solar plants, thermal storage provides a higher capacity factor and increased dispatchability, both of which lead to increased revenue. Cubic estimates that its thermal storage solution requires capital costs of only $4/kWh compared to over $20/kWh for molten salt systems. However, although there have been a number of recent major CSP installations in the American southwest, the technology has had very stiff competition from utility-scale photovoltaics and there are not many active new projects at the moment.
During this period of relative inactivity in the thermal solar marketplace, Cubit has turned its attention to natural gas CHP systems and is using its expertise to develop technology to make use of waste heat in these facilities. A current project is a packaged ice facility on Staten Island and its 10 MW CHP system. The idea is to make use of waste heat from the natural gas system in order to produce refrigeration. In the future, waste heat could be stored in the latent heat system and thereby shift the load to more desirable times of day.
Cubit’s Chief Operating Officer, Alan Powell commented: “We see renewable and clean energy generation as the way of the future, not only from an environmental standpoint but more importantly from an economic one. Our goal as a company is to find ways to generate and store renewable and clean energy at a levelized cost that is competitive with existing technologies.”
Cubit Power is an innovative startup company that is developing a variety of technology solutions embodying novel energy storage techniques and other approaches to enhance energy systems.