Renewable Energy and Storage

There’s a missing piece of the puzzle for renewable energy. On the supply side, both solar and wind farms are now cheaper to build than coal fired power. And on the consumer side, governments, companies and individuals all want to make the change. So why are we still reliant on fossil fuel?

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The missing piece of the puzzle here is storage. Specifically, the storage of energy at a large enough scale to support the entire grid reliably with renewable energy around the clock. This is so important because both solar and wind are intermittent – they’re not available all of the time.

To achieve energy storage of this magnitude, our storage method needs to be both scalable and economic.

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 as heat. This heat can be obtained directly from a heat source such as the sun, can be obtained by electrically powered heating elements, or come from the waste heat of industry. 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 cheaper than batteries [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. Click here to find out 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