The cost of wind & solar power: batteries included
For some time now we here on Energy Matters have been harping on about the prohibitive costs of long-term battery storage. Here, using two simplified examples, I quantify these costs. The results show that while batteries may be useful for fast-frequency response applications they increase the levelized costs of wind and solar electricity by a factor of ten or more when used for long-term – in particular seasonal – storage. Obviously a commercial-scale storage technology much cheaper than batteries is going to be needed before the world’s electricity sector can transition to intermittent renewables. The problem is that there isn’t one.
Assumptions:
Making detailed estimates of the future costs of intermittent renewables + battery storage for any specific country, state or local grid requires consideration of a large number of variables, plus a lot of crystal-ball gazing, and is altogether too complicated an exercise for a blog post. Accordingly I have made the following simplifying assumptions:
* The grid is an “electricity island” – i.e. no exports or imports.
* It starts out with 30% baseload generation and 70% load-following generation . Renewables generation, including hydro, is zero.
* Baseload and load-following generation is progressively replaced with intermittent wind and solar generation, with baseload and load-following generation decreasing in direct proportion to the percentage of wind + solar generation in the mix. This broadly analogs the approaches a number of countries have adopted or plan to adopt.
* Annual demand stays constant.
* Enough battery storage is added to match wind + solar generation to annual demand based on daily average data. Shorter-term variations in generation, which will tend to increase storage requirements, are not considered. Neither is the option of installing more wind + solar than is necessary to meet demand, which will have the opposite effect but at the expense of increased curtailment (see this post for more details).
* Transmission system upgrades are ignored.
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