Thermal Electricity Storage by a Thermodynamic Process: Study of Temperature Impact on the Machines

International audienceThis paper presents different ways of storing electricity to overcome the intermittency of renewable energies. After reviewing existing storage technologies, a new way of storing electricity thermodynamically on a large scale is presented. This system is based on the principle of a high temperature heat pump that converts electricity into heat. This thermal energy is stored in refractory materials, and at a later stage converted into electricity by means of a Joule cycle. The first mode -of energy storage- requires the use of turbomachinery - compressors and turbines - to operate under conditions different from those usually encountered. In particular, for the process to be efficient, the compressor must operate at high temperatures (500 to 1000° C). This represents a major technological barrier in the process due to the market unavailability of compressors capable of operating under such conditions. In this study the latest advances in the field of gas turbines are presented, including those concerning high pressure turbine blades, in order to adapt them to the compressor. These advances result mainly in changes in the composition of nickel-based superalloys and their implementation (single crystals) to achieve maximum wall temperatures around 950°C