What is a better option for utility scale storage – Batteries or Pumped-Storage Hydroelectricity (PSH).

We’re living in an ever evolving landscape of power sources, with both traditional and new-age renewable energy advocates are fighting for their slice of the ever growing pie. With the push towards more renewable resources we are constantly left with the dilemma of how to store the excess power that is generated during periods of low demand and make it available during times of peak demand, when the sun goes down or when the wind isn’t blowing.

Utility Scale Batteries – Are They Our Future?

These days when people think renewable energy storage their mind typically gravitates towards batteries.

Home energy storage has been all of the rage in recent years, with inflation and prices going through the roof people have been looking for ways to save money. in many areas people find installing solar to be a great way save money and coupling solar + a battery backup system makes complete sense.

In the bigger picture, utility scale battery plants are a great way to store renewable power in remote locations and locations with unstable grids. Utility scale batteries also offer forward thinking municipalities an alternative to fossil fuel peaker plants and a great long term storage solution for renewable energy.

Pumped-Storage Hydroelectricity – What is it?

Most people are not familiar with the term Pumped-Storage Hydroelectricity (PSH), but they are very familiar with a similar form of hydroelectricity – the hydroelectric dam.

While similar to a dam, pumped-storage hydro can either be an open or closed-loop system, and uses the excess renewable power generated during times of low consumption or high production to pump water up-hill. During times of low renewable power production water is then released downhill, where it spins a turbine and produces electricity.

The flow, and ultimately power production, can be turned on almost instantaneously, so not only can PSH be used to provide a base-load, but in certain instances it can be very effective as a peaker plant as well.

Pumped-Storage Hydro is 80% efficient, meaning you can reclaim 80% of the power used to pump water to the top reservoir as you release it through the turbines downhill.

Open and Closed Loop Pumped-Storage Hydroelectricity
Pumped-Storage Hydroelectricity – photo credit https://www.energy.gov/eere/water/pumped-storage-hydropower

Reason #1: Batteries degrade and have a finite lifespan, PSH stations lifespan are much longer.

Just like most things in our everyday lives, rechargeable batteries of all chemistries degrade with every charge and discharge cycle.

Most modern batteries have between 500-1500 complete charge cycles, meaning they can be charged to 100% and discharged to 0%, before their service life is expected to come to an end. There are a number of companies that are working towards recycling as much of the battery materials as possible, some are reclaiming nearly 95% of the battery materials today.

Reason #2: Battery supply constraints will create demand issues for years to come.

With automakers making the switch to BEV and PHEV vehicles, home energy storage becoming increasingly popular, and the number of mobile devices being produced the supply chain for battery materials is going to be constrained for quite some time.

While PSH projects can take years to get into the construction process, the planning of projects for the future can help free up MWh’s of batteries for better use-cases.

Reason #3: Risk of fire with current battery technology.

Battery technology continues to get better, but manufacturers are still having issues with defects during production that can cause thermal runaway issues when the batteries are placed into commission. In addition to manufacturing defects, there are a number of potential circumstances that could pose an issue to this infant technology.

Pumped-Storage Hydro on the other hand has very few moving parts and has an extremely low probability of catastrophic failure.

Do We Need Both Batteries and PSH?

In short, yes.

Both forms of energy storage will be needed to move us towards a completely renewable future, but looking at the big picture, PSH is a far more viable solution to energy storage at the massive scale that needed at a utility level.