The Battery as an Energy Storage System; the existing link?

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Jonatan Höglund, Analyst at PBI

Of late, the proverbial wave of renewable energy that has swept over parts of the world has been coupled with the clearer understanding that in order to fully utilize their planet-saving potential, the issue of intermittency needs to be addressed and solved; Intermittency, in energy industry jargon, meaning the fact that the sun does not always shine, the wind does not always blow, and actual non-proverbial waves do not always sweep the oceans. So how do we deal with the fact that the planet rotates, and that air blows around to equalize pressure?

The intermittency of renewable power, i.e. how much and how quickly the amount of power generated by renewables varies, is the subject of much debate and has caused an on-going transformation in the energy markets and energy infrastructure. The existing conventional energy infrastructure is built around the combustion of various fuels that ultimately turn turbines of various shapes and sizes to generate electricity and heat. These legacy plants are often only efficient at a certain output level (i.e. running them at say half-output is horrendously inefficient and hence not feasible) and can take anywhere from 10 minutes to several hours to turn-on and get up to speed and start supplying the grid with power. The aforementioned start-up time is one of the hurdles related to the increase in renewable power generation that we must overcome in order to transition the world’s power generation to more sustainable energy forms.

Conventional combustion power plants are usually not fast enough to react and turn on following a sudden drop in renewable power, and in order to effectively handle the gap that results (and prevent black-outs), industrial energy storage in the form of big batteries can be used to provide in-between power while the combustion gets going. This then, is one solution to the intermittency problem, and something which can enable electricity grids and utilities both large and small to invest in renewables with renewed confidence, knowing that the flow of energy is secure and compatible with existing legacy generation forms.

Batteries are not the only form of energy storage, but they are much easier and quicker to deploy than building out other forms of industrial scale storage such as pump storage hydro power. Batteries are also becoming increasingly more affordable, although on a EUR/capacity scale they are still far more expensive to build than conventional power plants. However, their unbeatable flexibility makes batteries nigh on incomparable against other forms of power generation.

Batteries can be charged whenever it is cheapest, aka when there is an abundance of generated electricity, and then discharged onto the grid whenever necessary and almost instantly, with a reaction time of only a few milliseconds. This means that batteries can be used as energy sinks when there is oversupply in the grid (more on this in a later post!) and as a temporary generator when there is an energy undersupply in the grid. The quick reaction times of the battery then maintains the load in the grid as conventional generators start up and take over (e.g. in a sudden drop of solar or wind power). t

 Shown above is the energy curve of a solar energy system experiencing a sudden drop in load midday due to weather conditions and the energy storage battery reacting instantly to keep the total load constant. Notice that the battery charges whilst the solar load is constant during the morning and afternoon

Shown above is the energy curve of a solar energy system experiencing a sudden drop in load midday due to weather conditions and the energy storage battery reacting instantly to keep the total load constant. Notice that the battery charges whilst the solar load is constant during the morning and afternoon

Renewable energy sources such as solar and wind are making headlines hourly, but if they are not able to play nice with the existing energy systems without unacceptable risks such as brown- or black-outs, then it will take that much longer to get rid of our legacy greenhouse gas emitting plants. The enabling of renewable energy to augment the existing energy system through solutions such as batteries, is the existing missing link that eases the transition to a planet-wide renewable energy system.

Jonatan Höglund