Why

The world needs to meet renewable energy targets laid out by the climate experts, that much is known. However, the agreed upon method to reach these targets is a matter of much contention. Is it a matter of reduction, more efficient fossil fuel technologies, a carbon tax, legislation to boost renewable technologies, or some combination of the above? Questions about which renewable technologies should be focused on, which are the most economic or produce the most power, are also prevalent.

Regardless of the answer to all of these questions, one fact holds true: deployability is key.

Deployability is the ability for supply of electricity to meet demand, electricity is essentially instantaneous, the electricity used to power the screen you are reading this text on was created only moments ago.if you don’t use the energy immediately it is wasted in our system.  The largest forms of renewable energy are solar and wind, both of which suffer from what is called intermittency.What if the wind isn’t blowing, or the sun isn’t shining, when you need to use electricity? The only way around this problem is storage.

Storing electricity in batteries is a mature and long standing technology, however, implementing very large scale electricity storage in batteries is uneconomic due to high initial cost, relatively short lifespans, charge/discharge inefficiencies (due to heat loss), and limited recyclability.

An alternative method, is to store the energy captured as heat. This heat can be obtained directly from a heat source such as the sun in what is called a concentrated solar power plant. Or can be obtained by electrically powered heating elements. Peak supply of renewable energy such as solar does not align well to peak demand (in the mornings and evenings). As such, this power would be wasted unless stored in a battery or thermal storage system.

Storing energy as heat is over 10 times more economic [1], as shown in Figure 1, and also more efficient than storing it as electricity. This is because thermal storage systems are generally cheaper, have very minimal losses over time, and very high thermal efficiencies. The thermal energy can then be converted to electricity through a standard powered generation cycle, such as those used in traditional coal or gas fired power stations.

Battery vs TES economics
Figure 1: Cost of energy storage media [1]

The current industry standard for thermal energy storage is molten salt, initially designed for load control in coal fired power stations. However, they have proven difficult to economically implement into concentrated solar power plants due to very slow charge/discharge processes. Additional infrastructure and design is sometimes implemented to improve the charge/discharge process, but to limited effect. Molten salt storage is also limited by low energy density (expressed in Units of Energy per volume, Joules/Litre), high corrosivity, and low operating temperatures which results in relatively low electricity generation efficiencies.

This all sets the scene perfectly for a new thermal energy storage system which can solve the problem of deployability in a cheap, feasible, and reliable manner. Miscibility gap alloy technology is the solution.

Miscibility gap alloys have fast charge/discharge characteristics, very high energy densities, and can operate over a very broad range of temperatures. They are safe, compact, modular, have a very long life span and are highly recyclable. The What page will give you all the details on just how these new materials work and what makes them so special.


References:

[1] Brinsmead, T.S., Graham, P., Hayward, J., Ratnam, E.L., and Reedman, L. (2015). Future Energy Storage Trends: An Assessment of the Economic Viability, Potential Uptake and Impacts of Electrical Energy Storage on the NEM 2015–2035. CSIRO, Australia. Report No. EP155039