These geyser bots are smarter than other meters
To reduce the strain on the national grid during peak hours, regulators are considering cutting off power to household geysers. But there are far better options than this heavy-handed approach to demand management, which would bring a range of unintended consequences.
Among the technologies being piloted are systems that allow authorities to control your home’s electricity usage. Those include ripple relay systems — which are used to halt the supply of power to geysers — and load-limiting smart meters, which suppress electricity supply to households.
There are several downsides to this strategy, including that it leads to sudden spikes in demand when geysers are turned back on — unless they are brought back online in a staggered approach, though that would prolong power cuts. And, in a typical family home, roughly 15% of showers will be cold in the winter if we go this route.
A recently concluded 30-month study in the Western Cape has proven that there is a better, less disruptive way forward.
Under the pilot study, 500 geysers in Cape Town and the Hessequa local municipality were equipped with AIenabled devices developed by the Cape Town company of which I am CEO, Plentify. This energy technology company is backed by US climate-tech investor Third Sphere.
In collaboration with the two municipalities, the German Agency for International Co-operation, clean-energy financing facility EEP Africa and others, we found that the devices reduced each geyser’s peak-period energy use by up to 80% — without compromising hot water availability. The devices, called HotBots, shifted each geyser’s energy use away from peak hours while still ensuring that residents had hot water when they needed it. In doing so, we reduced peak load by up to 430W per geyser, on average. Aggregated together, a fleet of HotBots can make a big dent in the nation’s energy crisis.
First, the HotBots shift a significant share of the usual morning peak energy use into the afternoon. That means water is heated when there is less strain on the grid, but closer to the time when hot water is actually needed for evening showers and other activities. Similarly, evening peak energy demand was shifted to the early morning when most people are asleep and power consumption is low.
In each case, energy use was only shifted to the extent it did not threaten the supply of hot water. The result was a four-fifths reduction in peak energy consumption, and uninterrupted hot showers.
In a city such as Cape Town, installing these devices in just one in four households could cut load-shedding in the mornings and evenings by a cumulative 20 hours a month. These findings were independently verified by the University of Cape Town.
The devices improved each geyser’s overall energy efficiency by up to 24% by switching them off when they did not need to be consuming electricity. Further, by co-ordinating the devices in such a way that each geyser drew power at a slightly different time, maximum demand at any point in time across the entire fleet was slashed by up to 60%. This, we believe, is far superior to the alternatives that are being tested in parts of the country. And this solution has been further refined since the early days of the study, meaning that the energy savings are now even better.
Rather than locking in suboptimal solutions for years or even decades, South Africa has an opportunity to emerge from its electricity crisis with a far more resilient and sustainable energy system in place — one that benefits both the grid operator and ordinary households. The study illustrated that we can see a meaningful reduction in peak electricity demand, a smoother load profile, lower household energy bills and a constant supply of hot water all at the same time, even in large households.
Bringing this to fruition will require collaboration between the government, municipalities, Eskom, businesses and households. In our view, “project smart geyser” has proven what is possible, and it is time to scale up our collective efforts.