University of Tokyo (UT) researchers have discovered a new type of material which stores heat energy for a prolonged period. Named a “heat storage ceramic”, the new material can be used as heat storage material for solar heat energy generation systems or efficient use of industrial heat waste. The breakthrough is the new material enables recycling of heat energy, since the material releases the stored heat energy on demand by the application of weak pressure, becoming in effect, a “heat battery”.
Today’s materials that are capable of storing heat include materials such as bricks or concrete slowly release the stored heat, and others such as water or ethylene glycol take in heat when they transform from a solid to a liquid. However, none of these materials can store heat energy over a long period as they naturally release it slowly over time. A material that could store heat energy for a long time and release it at the exact timing desired would be a boon for the field of renewable energy.
The heat storage ceramic discovered by the research group of Professor Ohkoshi at the University of Tokyo Graduate School of Science preserves heat energy for a prolonged period. This material, called stripe-type-lambda-trititanium-pentoxide, is composed of only titanium atoms and oxygen atoms, and can absorb and release a large amount of heat energy (230 kJ L－1).
The heat energy stored is large, at approximately 70% of the latent heat energy of water at its melting point (0º C or 32º F). Additionally, applying a weak pressure of 60 MPa (mega Pascal) to stripe-type-lambda-trititanium-pentoxide induces a phase transition to beta-trititanium-pentoxide, releasing the stored heat energy.
Along with direct application of heat, heat energy can be stored by passing an electric current through the material or irradiating it with light, enabling the repeated absorption and release of heat energy by a variety of methods.
Stripe-type-lambda-trititanium-pentoxide is a simple titanium oxide composed of abundant elements and is environmentally friendly. The UT group’s present heat-storage ceramic is expected to be a new candidate for use in solar heat power generation systems, which are actively promoted now by European countries, and also for efficient use of industrial heat waste.
This material also has possibilities for use for advanced electronic devices such as pressure-sensitive sheets, reusable heating pads, pressure-sensitive conductivity sensors, electric current driven type resistance random access memory (ReRAM), and optical memory.
Congratulations are in order for the UT group. Lost heat is one of the world’s most abundant, available and currently unused resources. The paradox has been storing it. This is a breakthrough of immense possibility, the idea of a “heat battery” is a breath taking concept. Spread the word, as more and perhaps even better materials and ideas for use are needed.