Energy storage: ‘Save it or lose it’

By Michael Rogers

With 1,660 hydropower plants, which accounts for 96% of total installed capacity, hydropower is the mainstay of the Norwegian electricity system (photo: MPE)
With 1,660 hydropower plants, which accounts for 96% of total installed capacity, hydropower is the mainstay of the Norwegian electricity system (photo: MPE)

No matter how power is generated – by fossil fuels or renewables such as wind or solar – an ongoing challenge has been what to do with excess power when production exceeds demand.

We’re all familiar with small electric batteries that we might insert into our gadgets. Now, for the most part, these are hidden inside our smartphones, smartwatches or electric vehicles, and we plug into an electrical outlet for charging – and soon we’re mobile again.

But imagine storing power for later use on an industrial scale – and some cases, “on the fly”.

Take Norway, for example, where most of the electricity is generated via hydroelectric facilities – making it the country with the highest percentage of electricity produced by renewables in Europe. Its use of reservoirs helps to ensure a steady supply of power, even during the drier periods and when the inflow to reservoirs is reduced.

Moreover, Norway’s energy strategy includes using its reservoirs as “batteries”. When electricity generation outstrips demand, water is pumped back into the reservoirs so it can be reused to compensate for inflow reductions. (find out more at the Norwegian Ministry of Petroleum and Energy (MPE) Energy Facts – Norway)

Another strategy is to use what otherwise would be “wasted” energy to generate power. It takes an extreme amount of work and time to stop a train. In addition to friction brakes, electric trains have long used regenerative braking – simply put, switching electric motors into “reverse” to act as generators – to recoup energy and slow forward momentum. The regenerated electricity is directed back to the grid.

At sea, we now see ships, oil platforms, as well as drilling rigs, that now make use of the heat generated by various work processes, cycling it back into the systems that generate onboard power. Much like the regenerative brakes of an electric train, these systems take advantage of energy that would otherwise be lost.

Excess power from renewables can be used for storage that goes a long way towards compensating for times when the sun doesn’t shine, or the wind doesn’t blow. Excess power for can be put to work on the spot to strip the hydrogen from water. Likewise, storage in electric batteries or thermal storage in a variety of mediums are now possible.

The International Energy Agency – the IEA – sees support for Energy Conservation through Energy Storage (ECES) among its top priorities for supporting the energy transition. The IEA Technology Collaboration Programme (TCP) is currently working with 38 international groups of experts to enable industry and governments to develop project and programmes in a wide range of energy matters, including ECES.

Specifically concerning ECES, the IEA TCP’s mission:

…is to facilitate research, development, implementation and integration of energy storage technologies to optimise the energy efficiency of all kinds of energy systems and enable the increasing use of renewable energy. Storage technologies are a central component in energy-efficient and sustainable energy systems. Energy storage is a cross-cutting issue that relies on expert knowledge of many disciplines. The ECES TCP fosters widespread experience, synergies and cross-disciplinary co-ordination of working plans and research goals.

Worldwide, the IEA notes that the most effective uptake of storage technologies occur where government support is greatest:

Energy storage deployment reached a record level in 2018, nearly doubling from 2017. Behind-the-meter storage expansion was particularly strong, almost three times that of 2017. The leading country was Korea, followed by China, the United States and Germany. New markets have emerged quickly wherever governments and utilities have created supportive mechanisms, including in Southeast Asia and South Africa, indicating that storage continues to need policy support.

Energy storage will play a key role in the development of increased energy efficiency, a necessity to work towards meeting energy demands while lowering greenhouse emissions – continued and increasing policy support will help to maintain the momentum.