Posted by Stuart

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Recent Work – Energy Storage

For a while now, I have been one of E.ON’s technical specialists in (electrical) energy storage, looking at the different technologies, operating parameters, costs and benefits, and advising the business on which the most appropriate system is for each potential application. There is no single “best” energy storage technology – like many things in life, there are a number of “good” ones for a particular job – and my role has been to cut through the hype and hyperbole and advise E.ON’s decision-makers which one is best for each project they have.

A number of key parameters define energy storage technologies and how good they will be for each task:

  • Their capacity (often given in kWh or Ah) – how much energy they can store.
  • Their charge/discharge power (kW or A) – how quickly they can provide or absorb energy.
  • Their energy- or power-density – how much space they take up.
  • Their lifetime (years, cycles, energy throughput) – how long they will last.
  • And obviously, theirĀ cost – which could be capital cost, O&M cost, cost of delivery of energy, lifetime cost, etc…

The roles that energy storage can be put to work in are many and varied; normally up to 20 different “applications” are listed in technical literature, of which arbitrage (storing electricity when it is cheap, and selling when the prices are higher), and frequency response (trying to keep the grid running at 50Hz) are the most well known.

These two options demonstrate nicely how different technical requirements exist for “energy storage”: arbitrage relies on storing large quantities of energy, and the charge/discharge power is of secondary concern; as the grid frequency fluctuates above and below 50Hz on a timescale of minutes, frequency response services tend to value power delivery much more highly than the quantity of energy stored. Hence a range of different energy storage technologies will likely be required to support the future energy grid at the lowest system cost.