Getting Big Batteries (BESS) & Pumped Hydro (PHES) to Play Well Together

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At a recent Solar Citizens rally in the seat of Dixon, I had the intellectually stimulating opportunity to converse with Mike Westerman of GHD about the viability of pumped hydro (PHES). 

Mike is the lead for GHD on hydropower. GHD (named from the initials of the founders, engineers Gutteridge, Haskins, and Davey) states that it is “committed to making water, energy and communities sustainable for generations to come.” Mike’s LinkedIn profile tells us that he has had “success in developing pumped hydro in Australia so now focusing internationally on Scotland, North America and Middle East pumped storage developments.” He has had “all levels of experience to director level in engineering consultancies in energy sector. Particular expertise in contract administration and hydro engineering, from pre-feasibility to refurbishment.”

The conversation opened with the view that it is not either BESS or PHES, but both. With his high level of expertise and my lack of knowledge, I thought it best to let him explain his view without too many interruptions from the peanut gallery. By email, he told me:

“We need both BESS and PHES. I expect that for the next 2–3 years BESS is going to explode (due to slower growth in EV sales — evil empire fights back).”

He explains more fully:

“Although global manufacturing of batteries would struggle to convert the world’s ICE fleet inside of 30y, current demand is about a third of that capacity. Hence EV makers are heavily discounting, and BESS developers are making hay while the sun shines with fantastic deals. I don’t see that lasting as the potential demand as above is well in excess of supply, and the big battery investors particularly in China will be reluctant to invest in more capacity till they have better recovered from their previous investments, and so I anticipate that in 2-3y time we could well see battery prices holding at current levels. Another factor as you mentioned is that at present globally the recycling industry is very immature and as an adjunct, the storage of spend batteries pending their recycling has been quite haphazard, resulting in a number of fires. There have also been some spectacular and broadly discussed fires in BESS installations especially early facilities where fire safety was inadequate. Insurers have responded by tougher standards on BESS installations but it could reasonably be expected that they will be very reticent to cover recycling plants until acceptable standards around fire protection and suppression are worked out.

“We need to explore what is unique about PHES and why Australia in particular should get going in building them (and how the government could provide the key without having to either fund them or take all the risk on each project).”

Readers may recall my earlier article on this. Note especially the link to the interactive ANU map showing possible sites.

Mike explained how BESS and PHES could play together for the benefit of the grid:

“Let’s look at the technical, essentially BESS is a totally digital gadget, while PHES is analogue. BESS uses an inverter that creates the AC waveforms from lots of little steps and then smudges them together with a filter to get rid of the noise. But the controls are still digital: it samples voltage, current, phase and frequency at small time intervals and compares them with set points. It calculates not only the errors, but also the rate of change of the errors and the cumulative value of the errors, then does the maths to work out how to respond.

“Obviously, it needs more than one point on the graph to do all this but also the error has to be more than that which it is told to ignore. For voltage disturbances which can rise very quickly, the response can be very fast almost instantaneous while for frequency will be slow, and also for smaller perturbations. So, there is some compromises arising from the fact that the digital response has to be stable but quick, but also keep the device within its ratings. Inverters tend to fall off in efficiency dramatically off their maximum rating, simply because the waveform is created by switching circuits on and off rapidly and so are optimised for the rated output. This doesn’t leave much up their sleeves for overload, and as you know with digital devices around your home, they are generally robust but if they run into overload – they burn out.

“Solid state digital devices are robust if within their ratings, but push them outside that and they fail rapidly: very much all or nothing. BESS themselves also behaves very differently from PHES in terms of discharge of stored energy and the impact on life span. Because BESS is a chemical storage, it can be subject to thermal runaway, but also to degradation the rate of which is dependent on how they are treated: run hard – high current and deep discharge – and the degradation rates go up. PHES because it stores by gravity and converts potential to electrical energy at low temperatures suffers very little degradation over extremely long lifecycles, and even at overload, damage occurs progressively without a “tripping point”.

“So, although BESS are fast and react very well to smaller, shorter perturbations they run into their limits rapidly. They can also interfere with each other if not tuned to behave appropriately given the characteristics of their local network. So, if a network is very robust and well behaved and a bunch of inverters start trying to over compensate for perturbations, they can quickly knock each other over.

“The trouble is that the most money can be made in arbitrage and network services in areas with pretty good network characteristics, unless you are a BESS connected “behind the meter” that is directly to a solar or wind farm specifically to fill in for when those energy sources fluctuate. So, BESS have to decide what job they are there to do and what else there is on their local network. That’s what makes PHES a good friend – a bit like having some big forwards to balance the lithe wingers on your team.

“Because PHES has big chunks of rotating masses and very strong magnetic and electrical fields all directly connected to the network, they literally must respond instantaneously, no calculations or sampling needed but the stored energy to do so is limited unlike the total storage in a battery. But like the forwards, they can take a real hammering over a prolonged period without giving up, giving the protection devices on the network time to sort problems out. They particularly excel at frequency stability but to keep reacting appropriately on voltage and phase they use clever electronics and so that is a bit slower, needing to respond to not only errors but trends and accumulation, much in the same way as the inverters on the BESS.

“The big challenge with PHES is not so much the actual capex (higher than BESS for power that is $/MW but cheaper for energy stored that is $/MWh) but that there is a lot a risks and unknowns at the time the deal needs to be signed. And as we’ve seen with every large project in Australia, the proponents fib about the likely cost because they don’t want the projects killed off and contractors load up with risk premiums. One possibility is for governments to provide “insurance” for that risk in exchange for hefty returns late in the life of the projects when the private investors have already made their money. That way the government is essentially betting on the future, and if it scrutinises projects carefully and holds the proponents and contractors to account (that is scrape out the risk premiums, do a realistic estimate for the most likely price and then cover the risk premiums that shouldn’t sit for the above, for example unknown geology or future labour rates or crashed currency).”

I asked Mike for an example of projects that he has worked on, and he gave me two:

“Kidston: the first and only (as far as I know) repurposing of a mine to a pumped hydro, currently under construction in North Queensland. I assisted the contractor in securing that project and took it to GHD who did the engineering of much of the project. 250MW x 8h so even though small as far as pumped hydro goes, it is as big as the biggest BESS. It should be online mid next year. Pic attached. The project was developed by listed Genex but sold recently to the Japanese energy giant J-Power.”

“Phoenix: first and only PHES to execute a long-term energy services agreement with the NSW government that provides revenue support to the project, helping with reaching financial close. At 800MW and up to 15h generation it will be a significant support to the Renewable Energy being built in the Central West Orana REZ in NSW near the town of Wellington. GHD identified the site, carried out the studies including the geotechnical and environmental site investigations, and completed the reference design used to invite contractors to get involved (a process just starting). The project is owned by the Filipino energy powerhouse ACEN.”

As part of our discussion, we looked at Michael Barnard’s recent CleanTechnica article. Mike admits that he is a fan of Barnard’s work and adds: “Water is an amazing medium: dense enough, fluid enough with relatively low viscosity, non-volatile, non-toxic, abundant and multi-purpose.”

By the by, Peter Dutton, leader of the conservative Liberals (now there’s an oxymoron) lost the seat of Dixon as the people of Australia rejected Trumpism and backed a cleaner solar powered future.