Editor,
I do not have expert knowledge on pumped storage efficiency. But 35+ years in IT has taught me how to find and research information using the latest tools. When Mr. Carr asserts that, “at best, pumped storage is 70% efficient”, I was curious. I decided to learn about this.
I’ve been using internet searches and an AI tool to collect information about pumped storage. Here are some findings:
Pumped storage is known for its high efficiency in storing and releasing electricity. The overall efficiency of a pumped storage system is typically above 70% and can reach levels as high as 87%. This efficiency includes both the energy used to pump the water from the lower reservoir to the upper reservoir and the energy generated when the water flows back down and drives the turbines.
The efficiency of pumped storage primarily depends on factors such as the elevation difference between the two reservoirs, the size and design of the system, and the efficiency of the turbines and generators used. Higher elevation differences generally result in higher efficiencies, as more potential energy can be stored and converted into electricity.
It’s worth noting that while pumped storage is an efficient method of energy storage, it does have limitations. It requires suitable geographic conditions (Meaford works) and significant capital investment for construction (private not government money). Nonetheless, pumped storage remains one of the most mature and widely used technologies for large-scale energy storage and grid stabilization.
The efficiency of pumped storage is generally higher compared to many other methods of energy storage, especially when considering large-scale storage applications. However, the efficiency of energy storage technologies can vary depending on various factors, including the specific technology, scale, and operating conditions.
Here’s a comparison of pumped storage efficiency with some other common energy storage methods:
- Lithium-Ion Batteries: Lithium-ion batteries are widely used for smaller-scale energy storage, such as in electric vehicles and residential systems. The round-trip efficiency of lithium-ion batteries typically ranges from 80% to 90%, depending on the specific battery chemistry, system design, and operating conditions. This efficiency can decrease with age and the depth of discharge. From practical experience with EV batteries for 9 years and now a 20kw solar system paired up with 40kw of Tesla powerwall batteries I am learning that they can’t be efficiently charged much beyond 80%. This becomes a consideration when sizing and buying battery based grid storage. The useful lifespan of lithium based batteries is not known with certainty (likely a few decades) but there are many examples of long lived pumped storage systems. (Many decades) The technology is well known and proven.
- Other technologies like: Compressed Air Energy Storage, Flywheel Storage, Hydrogen Storage, Flow Batteries, etc. are good in specific use cases but generally don’t provide enough efficiency and scalability to be considered for large scale grid storage.
Beyond the efficiency issue, which I am learning is not be a big deciding factor, I am curious about Ontario’s plans to meet peak energy needs of the province.
Where will the electricity will come from to charge the selected grid storage device(s). Ontario does not have infinite off peak capacity for renewable electricity generation.
Current capacity of Ontario generation stations is:
27,561MW (renewables)
10,515MW (gas generation)
The 20-year average daily generation (including gas) is 20,000MW. So we do really need a 1,000MW grid storage facility soon to offset carbon based generators and to help stabilize the grid?
For climate change reasons we should be eliminating gas-powered generators.
The Nuclear plants do go offline for long periods for extensive, expensive refits. We are due for this soon.
Another of Mr. Carr’s assertions is that homeowners should divest of carbon-based fuels for home heating. While I do agree in principle, I think that asking Ontario homeowners (only 57.6% of us live in a private home) to switch to electricity from carbon-based fuels (gas, oil, propane, wood) is optimism in the extreme. The total costs to incentivize this behaviour, in a meaningful time frame, are unknown but not trivial. I asked for a quote to do this (including heat pump) for my home. It came to $9,633.22. This is exactly why the big oil companies promote this because they know this approach is impractical and will extend the life of their oil based infrastructure.
Solar and wind can help, but only if there is significant government investment. Sadly, politics, nimbyism and oil company lobbying are pressures our politicians face that prevent them from making good long term decisions.
Gas-based peak energy is just folly. It exacerbates the CO2/climate issues.
As EV adoption increases, off peak energy resources will get ever smaller.
Bottom line…
Ontario needs reliable grid storage. Meaford Pumped storage is the way.
David MacDougall, Meaford
