Eos Energy Storage Writes With an Amusing Lilt
One of the things I like most about my friends at Eos Energy Storage is the cleverness and sense of humor of their writing. In their website’s piece about the need for storage on our grid, they quip, “Sushi has better storage.” I.e., even though the electricity market is the single largest supply chain on the planet, it is the only supply chain in the world that has almost no storage at all.
They write:
Every commodity in the world—oil, gas, coal, grain, manufactured goods, textiles, everything—has storage to enhance the efficiency of the supply chain. Even sushi, which like electricity basically needs to be consumed as soon as it is produced, has storage in its supply chain. Imagine how difficult it would be to get good Japanese food if there had to be a handy fisherman standing by to jump in a boat and catch a tuna every time we ordered maguro sushi.
Yet that is how we run our electricity grid. As a result, the grid is massively overbuilt to accommodate the few hours each year that we reach peak demand. In the US, 25% of all distribution assets and 10% of all transmission and generation capacity is used less than 400 hours each year.
That’s sure something to think about as we continue our discussions on smart-grid. Sure we can use advanced IT to create better efficiencies in the way we generate, transmit, and distribute electricity. And yes, the two-way flow of information to and from the consumer is an even greater potential benefit from smart-grid. But as long as we need to consume the electricity we’re generating that very moment, we’re doomed to this hopeless overbuilt and super-expensive infrastructure.
It’s true that on the average, our grid is operating at considerably less than full capacity so that it can handle the situation when demand is high. Wind and solar power have a similar, but not identical, situation.
Because the wind is not always blowing and the sun, on average, is shining considerably less than 50% of the time, using wind and solar sources of energy require considerable over-building. That would be true even with storage. For example, if a wind farm on average produces only 30% of its rated power and if wind were our only source of energy, then wind farm capacity would have to be 3.3 times greater, even with unlimited storage, to be the equivalent of a power source that could deliver its rated power 100% of the time. Obviously that has cost implications.
“But as long as we need to consume the electricity we’re generating that very moment”
I would suggest that the reality is actually the reverse, i.e. ‘we need to generate the electricity we’re consuming that very moment’, as generally the generators follow the load not the other way round, although there can be exceptions, when supply can’t be turned down as fast as demand drops.
There are two basic problems associated with peak demand, peak generation capacity and peak transmission/distribution capacity. To reduce the ‘over-building’ of both of these aspects we not only require adequate storage but it needs to be distributed, located at the point(s) of use so that generation and the grid run predominantly at average load, i.e. located in homes and businesses.
Demand peaks also have a seasonal element which can be significant in some countries, particularly those with cold winters.
For homes that use substantial amounts of electric heating in winter providing for this storage locally could require substantial storage capacity. For example; based on my house’s energy use (3 bed semi-detached), on cold winter’s days I probably consume about 5KW extra power for heating than in summer, that’s an extra 120KWh/day. If we assume that I had a heat-pump running at a COP of about 3 this would reduce to say 40KWh/day. To level out this use I would need to take more energy in the summer and store it for winter giving a level demand of about 20KWh through the year. If we assume we have to store say about 3 months worth in the summer to supplement winter use/supply this is about 1200KWh. At EOS’s comparatively low price of $160/KWh this is $192,000 and as this is a seasonal use we are looking at moderately low charge/discharge cycling periods, giving hundreds of years of service life based on EOS’s stated cycle life for their batteries, this doesn’t strike me as a reasonable investment.
The conclusion is that battery storage can only provide a limited solution to the problems of peak demand, particularly in countries with climates similar to the UK. It is probably limited to a few tens KWh’s worth per home for use to offset daily peaks, and prorate for businesses. The remaining chunk of peak power will still need to be met by providing additional capacity in generation and distribution and storing the energy cheaply in fuels, currently mainly fossil and nuclear with a gradual shift to renewable sources such as biomass or renewable synthetic variants.
Don’t get me wrong, I think this technology is a fanstastic step forward in energy storage but ‘A technology must know its limitations!’.