re: “Essentials to meet South Africa’s electricity need” by Alex Ham in the May 2020 edition of Energize.
The article does not look at the overall energy ecosystem in a balanced way. Being an advocate of clean energy storage solutions, the following paragraph specifically indicated to me that the author is years behind on what is going on in renewable energy technology:
“With the power demand on our grid currently peaking at about 30 000 MW, no battery system in the world, can instantaneously meet sudden large increases in demand. This can only be achieved by rapidly ramping up the output of plant already in operation and at partial output. This is an essential dynamic factor to bear in mind in deciding the extent to which we can depend on renewable energy systems.”
As a matter of fact, it is one of the features of battery storage systems that batteries are ideal for many auxiliary services on the grid, including frequency control. In the retrospect reports on the blackout experienced in part of the UK in August 2019, two things stood out: (1) that without batteries they would not be able to get the grid up and running as soon as they did, and (2) that if they had sufficient battery capacity, the blackout would not need to happen in the first place.
This was highlighted in an article “Batteries and the blackout: how energy storage saved the UK’s grid” in the online Energy Storage News. This article described what happened behind the scenes in the 9 August 2019 blackout experienced in the UK. The article mentions:
“It took just two minutes and 22 seconds for that combination of load shedding and frequency response – a not inconsiderable amount provided by batteries – to restore the frequency to safe levels, four-times faster than the last time such an incident occurred in 2008. Within four minutes – 3:47 to be precise – grid frequency had been restored to its usual operating limits, significantly quicker than the 11 minutes it took a decade ago.”
The specific US battery technology that I am promoting for stationary energy storage applications in Africa, the ESSINC Iron Flow Battery, can go from zero to full power in less than one second, while it is scalable from mini-grid to utility scale through different configurations. In fact a laboratory test result shows a DC “zero-to-full rated power” result of 0,4 ms.
Due to the latencies of the balance of the system, ESSINC specifies the response time for a 400 – 480 V AC system as <1 s. This is exceptional for any long-duration (>12 h) battery solution.
It is also well-known that batteries are beginning to replace gas peaking plants for fast response solutions on the grid. There are many articles available on the topic, e.g. an Energy Storage article on a BloombergNEF paper under the title “Already cheaper to install new-build battery storage than peaking plants”, and a Renew Economy article titled “Battery storage as substitute for gas peakers – better performance, lower cost” which states:
“Aside from the cost advantage, batteries have much faster response time – they can virtually ramp up and down instantly by following signals from the grid operator. This makes them so much more useful allowing them to respond to fluctuations in solar or wind generation – say variations in wind speed or changes in solar output temporarily obscured by passing clouds. Gas peakers can barely match the flexibility and fast response time of batteries.”
It would be interesting to see an article by someone like Prof. Anton Eberhard from UCT or Prof Wikus van Niekerk from US, who is informed on the latest technology, on the topic of the role of batteries in stabilising the grid.