Stored Hydropower: an overlooked battery storage solution

Photo by Aoumeur Abderrahmen on Unsplash

Energy storage is often put forward as the main limiting factor to a 100% transition to renewable energy. The argument goes: “Because of the intermittent nature of renewable energies i.e the sun doesn’t always shine and the wind doesn’t always blow, we require an enormous amount of batteries, an amount which our raw material reserves cannot possibly meet”. In fact, some proponents of Nuclear and Fossil Fuel don’t even concern themselves with the battery part of the argument and suggest that the intermittent nature of renewables is enough of a block, in and of itself, to render them unfeasible. They are simply wrong. So wrong you can see the strings being pulled.

The thing is, we don’t NEED to generate as much energy as we currently do. Our current means of energy production and distribution, via fossil fuels, waste a whopping 70% of energy in the form of heat.¹ “Primary energy” is the total energy contained within fossil fuels before we convert it to energy we can actually use, such as the electricity and heat for our homes. This is known as “final energy” and it is this conversion process that incurs enormous waste.

Solar and wind energy systems, on the other hand, supply electricity directly as “final energy” thus skipping the wasteful conversion process. Consequently, estimates to replace all primary energy with renewables are misguided. Since solar and wind systems operate differently, they only need to replace the final energy amounts. If you have the time, and inclination, Nafeez M. Ahmed goes into much more detail in his brilliant newsletter from “Age of Transformation”.

But for now let’s look specifically at a form of energy storage which receives little attention. In fact, you’ve probably never heard of it yet it’s the world’s largest battery technology, accounting for over 94% of installed global energy storage capacity, well ahead of lithium-ion and other battery types.² It’s called Pumped Hydro Storage.

The issue with renewable energy

As you know, Wind and Solar energy sources are intermittent and with intermittency comes a series of challenges. How can the smooth running of our society rely on energy sources that are not consistently available you ask? Fair question. Indeed, we all depend on the uninterrupted flow of electrons and unlike traditional energy sources such as fossil fuels, which can be controlled and dispatched as needed, renewable energy generation is subject to natural variations in our environment. Solar power generation depends on the availability of sunlight, which fluctuates with weather conditions, time of day and season. Wind power generation relies on wind speed, which can vary unpredictably. In reality, wind and solar happen to be complementary in that the sun often shines when the wind isn’t blowing, and vice versa, but this isn’t full proof and certainly not a responsible grid-management policy!³

As a result, the output from these renewable sources is not constant and thus poses several challenges.

Whilst there are some complexities associated to integrating intermittent renewables into the existing grid infrastructure it is far from insurmountable. Indeed it has been successfully implemented in many countries already. Firstly the grid must be capable of accommodating the fluctuating and decentralised nature of renewable energy sources this means upgrades and modifications to transmission and distribution systems. Secondly, ancillary services that support grid stability via frequency regulation and voltage control must be managed and maintained to ensure the reliability and resilience of the grid.

And most importantly, since the availability of renewable energy may not always align with high demand periods we may encounter shortages which usually require fossil fuel backup power sources, thus defeating the purpose of a transition to clean energy. The good news is we have many energy storage solutions which don’t rely on fossil fuels such as lithium batteries, flywheel batteries, compressed air storage, gravity storage and stored hydropower.

The challenges of intermittency can be overcome by improving forecasting and grid management techniques to better predict and accommodate fluctuations but we must also make use of innovative, efficient and sustainable energy storage technologies in order to ensure a continuous and seamless energy supply.

Harnessing the Power of Water

Source: Pumped storage hydropower

Pumped Hydro Storage is essentially a water battery. It’s a form of clean energy storage that is ideal for electricity grids reliant on solar and wind power.² It functions by using surplus electricity generated during periods of low demand and high generation to pump water from a lower reservoir into an upper reservoir. When demand increases and renewable sources are unable to meet demand because of intermittency, the stored water is released from the upper reservoir, passes through turbines and by doing so generates electricity through gravitational energy.

Stored hydropower effectively acts as a massive energy reservoir able to release stored electricity within seconds and provide reliable backup energy to the grid. Since it stores vast amounts of energy, it excels at long discharge durations which can last up to weeks. This is crucial in avoiding curtailment, reducing transmission congestion, and reducing overall costs and emissions in the power sector. Stored hydropower facilities have remarkably long lifespans which often exceed 50 years and when you consider their efficiency of over 80% it truly becomes one of the most capable forms of energy storage available.

We have the technology… So what the hell are we waiting for?

A future powered by 100% renewable energy is not an outlandish proposition. Mark Z. Jacobson already laid out a clear roadmap on how to get there back in 2009. For some countries this is already happening. In 2021, 10 countries — Iceland, Norway, Costa Rica, Albania, Paraguay, Bhutan, Namibia, Nepal, Ethiopia, and the Democratic Republic of the Congo — produced 97.5 to 100% of all their electricity from Wind, Water and Solar (WWS) resources.³ By building 3–5 times more generating capacity than we need, a meagre 35–90 hours’ worth of storage time meets our requirements, thus reducing the need for expensive battery solutions. RethinkX calls this generation of hyper-abundant renewable electricity at a quasi-zero marginal cost “Super Power”.⁴

The convergence of several key technologies that are improving cost and efficiency steadily means we are on the cusp of the most profound disruption of the energy sector in over a century. Renewables already offer the cheapest form of electricity in some regions of the world — and this trend is growing.⁵ Fossil Fuels assets will become stranded during the 2020s making new investments in these technologies from this point forward completely irrational.⁶

Despite this, we continue to open new gas fields, extend pipelines and prospect further and deeper for more oil under the pretext of safeguarding energy security. We must realise that is utterly unnecessary and serves only to line the pockets of an incumbent industry that refuses to care and refuses to stand down. An industry that is playing for time and bleeding the Earth until the bitter end. Our political class is weak and manipulated and will be remembered as such.

We have the technologies we need to give up fossil fuels for good, but we are led astray by the malicious spread of misinformation by political mouthpieces and lobby groups with vested interests. Stored Hydropower stands out as a robust and flexible energy storage technology to overcome the intermittency of renewables. Its capacity to harness the power of water and gravity not only offers significant benefits for grid management but also exposes the inefficiencies of traditional fossil fuel systems which waste the majority of their energy as heat. By leveraging stored hydro power’s vast potential and exploring innovative approaches such as super powering the grid, we can pave the way for a truly sustainable future.

Coordinating Action Orchestrating change. WeBeGreen.org is an environmental platform connecting grass root initiatives with like minded activists in your area. Read up about us here.

Sources

1. Waste Heat: Innovators Turn to an Overlooked Renewable Resource — Yale E360
2. Pumped storage hydropower
3. Renewable Energy’s Intermittency is Not a Showstopper
4. New Report: Rethinking Energy 2020–2030: 100% Solar, Wind and Batteries is Just the Beginning — RethinkX
5. Renewable Power Remains Cost-Competitive amid Fossil Fuel Crisis
6. Energy Report — RethinkX