Renewable Energy Storage: No Wind, No Sun, Now What?

Solar panels and wind turbines are great, so long as the sun shines and the wind blows. But what if they do not? Well, then we store the energy. But how? In this video I explain how high the risk of a cold, dark, and windless period is -- the "cold Dunkelflaute", and what energy storage we need for intermittent renewables.

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The paper with the estimates for carbon dioxide emissions from storage is here:

The estimate for the carbon footprint of lithium-ion batteries is from here:

00:00 Intro
00:31 The Dunkelflaute Problem
07:07 Energy Storage Options
14:04 Carbon Footprint of Energy Storage
16:59 What Do We Learn From This?
17:32 Sponsor Message

#science #environment #climatechange

[AdvocatusThei]

I have a story I wish to share that does not relate to the main point of this video and is relevant only tangentially to one part, but I think that people who watch Sabine’s channel might be glad to hear it.
It concerns flywheel energy storage. I used to work at a facility in the northern US which had undervoltage release mechanisms, meaning that whenever the incoming grid voltage dipped below a certain value even for a moment, as was often the case when a thunderstorm came through the area, the system would shut down. If that happened, it would take as long as an hour to restore the system to operation.
Later, while still with the same company, I moved to a similar facility located in Florida, the thunderstorm capital of the US. Before moving there, I thought to myself, “Oh boy, that facility is going to have a lot of interruptions.” Fortunately, the facility designers though of that and they included a flywheel UPS (uninterruptible power supply). The way it works is that the incoming grid power does not directly power the equipment. Rather it is used to power an electric motor which drives a shaft that 1) rotates a flywheel, and 2) rotates the rotor of a secondary generator that actually does provide the power to the equipment.
The benefits of this system are twofold. First, the output of the secondary generator is much “cleaner” than the incoming grid power, meaning the output THD (total harmonic distortion) is much lower than the incoming THD. Second, and more germane to the topic at hand, if the incoming grid voltage does momentarily dip below the acceptable level, the energy stored in the flywheel is sufficient to drive the secondary generator through that dip and no undervoltage releases are tripped. In fact, in the worst-case scenario of a total blackout, the energy stored in that flywheel is sufficient to drive the secondary generator until the on-site backup Diesel generators kick in.
If you read through my comment so far I want to thank you for letting me nerd out.

[brandurell]

I live in a country with a small energy grid, only 50.000 people (faroe Islands) with no cables to other countries to buy or sell electricity. We are building a pumped storage plant where we use excess power from windmills to pump water from one Lake to another. They estimate a yearly production of 60 GWh/year when finished. I think this is a good solution for us. A nuclear powerplant would be too big, I think for such an isolated and small country this is optimal🤷🏻‍♂️🇫🇴💪🏻.

[mikecolie]

The beauty of your videos is the clear, concise way you give information and the (not so) subtle way you express your opinion on something. No pie in the sky dreams. Just reality and what can be.

[alfredoalfaro]

"Unlike me water has a high heat capacity"

Sabine killing it as always.

[ydderynnad]

Long time metalhead, first time commenter: the heavy metal umlaut works best if the word *doesn't* originally have umlauts. Motor doesn't have an umlaut, nor does motley. Or spinal, for that matter. "It's like a pair of eyes, you're looking at the umlaut and it's looking at you." Cöld Dünkelflaute totally works.

[CharDaLuX]

I have been re-educating myself this last decade, and during this time I have found you on various platforms. I'm international, thus understanding many cultures, disciplines, sciences....and here express my gratitude to you for taking the time to expand my knowledge with a humor I have not often encountered. Vielen Dank, for giving freely. 👍😎

[danielhawkins]

Liquid air storage has a potential bottleneck when it comes to re-expansion. I was a facility manager for a semiconductor tool manufacturer that used a lot of LN2. We were constantly fighting to keep the heat exchangers de-iced to keep up the N2 flow. For something like energy storage, this is a non-trivial concern. You'd need a LOT of heat exchanger surface to keep the pressure up.

[veerkar]

Sabine, you are considering cost of production and supply from the power plant. Distribution to residential power outlets is by far the largest financial cost. In California, for every 3 cents of power production at plant, we spend 21 cents in distribution. Even if nuclear costs 2 cents to produce, it still costs 23 cents to buy in California, as compared to 24 from coal. However, when we use lithium batteries, the distribution cost is negative to individual consumer. The net cost of electricity comes down to minus 2 cents. Marginal cost is even lower at -6 cent a unit.

[nuttywasher]

The way Sabine delivers the Cöld Dünkelflaute line with a straight face... it breaks me every time 😂

[bentationfunkiloglio]

Antimatter should've gotten the most insanely expensive idea award. Cost of producing 1 gram of antimatter : $62.5 trillion (USD). Even so, it's an extremely appealing approach. It gives us unlimited opportunities to panic and yell with a Scottish accent (like Scotty from Star Trek). "Capt'n, I d'not think the engines can take any more. They're gonna blow! "

[damianhla]

I enjoyed your analysis. And many thanks for the useful information.

I have achieved 100% energy independence over 2 years ago. I am now on full Offgrid solar, disconnected from the power grid and the system is self sustainable, enduring the challenges with rainy, cloudy cold winter without issues.

My energy storage solution relies on LFP batteries.
The key towards achieving a working solution is to plan your capacity based on the worst case scenario. This means not just oversizing the solar, the battery capacity, but more importantly optimise how fast you can charge your batteries.

In our solution, we utilise 120Ah LFP batteries that are capable of accepting a 1C charge (120A) and providing 2C (240A) discharge. If you connect these in parallel, 10x of these will be capable of accepting 1200A charging current. In our setup, we have 16x of these, providing a theoretical 1920A max charging current at 14.2V. But in real life, dealing with such high current puts extreme demands on busbars and cables.

Based on current technology, my setup is based on the Victron Lynx, which has a 1000A busbar system.

The batteries are grouped into 4x groups of 4x, essentially 4x parallel battery banks, to split the current load. Each battery bank is serviced by a 500A flexible busbars. So if you combine these 4x you still get around 2000A. By having a very capable busbar system, the high current conductors run cold and efficient. We have independent temperature sensors on all 4x busbars system to monitor.

This extraordinary high current capability allows the deployment of multiple Victron SmartSolar units (we have 8x in this setup), each capturing solar energy for strategic groups of solar panels, which are placed/angled specifically to capture solar energy during a specific time of day and season, factoring the change of incident angle over the year and season. With a high multi-zone solar capturing setup, we don't need complicated solar tracking. The solar energy is captured efficiently by each group over the day without creating a single peak in the output, instead it provides a sustained output plateau we are aiming after. And due to the very high current capability of the busbars, there is no throttling required by the solar controller. Although we have set DVCC, it never engages. This means whatever short bursts of sun or cloudy diffused solar we get, we can totally capture these. This is important factor in winter survival for solar set-up. And we deployed Solar panels with the highest efficiency, the Sunpower Maxeon 3 400w panels, 16x of these. They perform extremely well even under cloudy and rainy conditions. And surprisingly, in winter as the temperature drops, the output voltage actually increases. You get more power in colder temperatures. And cloudy days does not necessarily means lower output. Actually under diffused sun you can still get pretty decent output, factoring the lower temperatures. And they go on for longer hours in diffused sunlight.
Based on our observations, our LFP efficiency is not bad at all as we tracked the energy we put into the battery and the energy we get out. LFP has an energy efficiency around 96 to 99%. We are seeing the 99%, which is pretty impressive. We only have a enter minimal compensation factor in the Victron BMS controller. And we only cycle our batteries between the 70% and 100% SOC. Leaving a high margin for contingency. This further increases the lifespan of the LFP battery as we are utilising shallow Depth of discharge.

Just as general guideline, on the worst days with crappy stormy weather, we get around 1/5 or 20% of the max daily average power. In winter, with slight rain, typically this is more like 30%. On cloudy days, this is around 50%. So if you plan and build according to the worst case 20%, a 5x oversizing (on both panels and battery) is probably the safer bet for a more robust solar power system with LFP storage. 😇👍 This means the design guidelines should be based on the worst weather, to ensure your solar panels should still be able to bring in sufficient power to cover your minimum energy needs. And obviously this value would be different for everyone and different regional climate.

I run our ebikes and e-scooters off our Offgrid solar. And the ebike combined with the escooter covers 99% of our travel needs. So i hardly ever use my car that has a petrol engine these days. It has been put on solar charger to maintain it's battery health 🔋😂

And i strongly believe if everyone makes a concious effort, they are capable of making a significant reduction on their carbon footprint.
We have proven that this is perfectly possible. And it's not like i don't have to travel far to be able to have a ebike as a viable commuting option. I still need to cover 60kms on my ebike travelling round trip to /from work. But surprisingly this doesn't take much longer than the public transport or even car when factoring traffic conditions. It takes me just under an hour to cover my 30km trip. So it is not like ebike solution is time consuming. On the contrary we would say it is not only as time efficient as public transport but way healthier solution. 😉👍

[seazenbones]

Thanks Sabine, I have been anti nuclear energy my whole life. I’m 61. I’m also an Australian Green Party member, where, ‘Nuclear’ is a dirty word. I believe that nuclear energy is our best hope to produce enough energy to power everything and is do-able right now. Thanks for the information and the clear, concise way you present it. Cheers.

[KitsuneSoftware]

Thanks! It's good to see some _real_ estimates on how large this problem is (and the pros and cons of the solutions), and not just the handwaving I normally encounter.

[Rocketsong]

Modern flywheel storage uses large flywheels, in vacuum, with magnetic bearings. Storage losses are about 2-3% per month, which is pretty good. Cost is somewhat better than lithium batteries.

Alaska uses a lot of flywheel storage for load balancing. Due to the large distances involved, there are a lot of micro-grids instead of one large grid, so power has to be balanced locally.

[somedayDefect]

I WAS an Engineer Technician for a green energy R&D think tank. We built a CAES system using shipping containers to ease transport and deployment issues. It worked so well and was so efficient we scrapped that project and moved to thermal energy storage. That can is still being kicked down the road to this day but the death knell is on the horizon. So much that we moved on to carbon capture. ... and because of this I so too moved on but you should see our impressive stable of unicorns!!!

[arildseterdalen]

I like how you teach, it's easy to understand your arguments, the technical details, just really fun to be taught by you.

[gneisenau]

I had a conversation with an engineering student when I was going to school in Germany in the 1970s. Nuclear power had a big PR problem at the time and had come to be demonized by some sectors of society. His view was that, sure, there is a problem with nuclear waste. But it's easily quantified and with appropriate technologies and sufficient political will, is pretty easily managed. CO2 from fossil fuel burning was in his view the far larger threat and one that's not nearly as easily quantified. The intervening decades have proven him right.

[russellthorburn]

It's a shame that the opponents of nuclear energy seem to have won by spreading irrational fear. Even if one accounts for all the nuclear radiation released by 3 Mile Island, Fukushima and Chernobyl, and it was summed, the total amount of leaked radiation is miniscule compared to the radiation thrown up into the air by fossil fuel burning.

[wernerruile]

Best idea I heard so far for Germany is to build large hollow sqheres at the bottom of the sea or lakes that are equipped with turbines which generate power if the water above fills the sqheres thus generating electricity. If energy has to be stored, then the water will be pumped out of the sphere. So we have pump hydro system without the problem of finding an appropriate location. But even better: in Germany we have the 'Hambacher Loch', a huge area where coal has been removed and now there is a hole which is about 450 m in depth. The idea is now to build these spheres at the bottom of this gigantic hole and then fill it with water. Calculations seem to show that this could solve the storage problems mentioned with 'Dunkelflaute' for Germany completely. (Distribution problems with the grid not taken into account). Industry (RWE) is interested and I hope that they will realize this project in the near future. Whats nice about it: no 'rocket science' required and first projects in the 'Bodensee' already showed that it works well, no 'bad surprises'.

[louishannett]

I found the video informative. I had worked at several pumped, storage hydro units in the USA. Also, I had been at the McIntosh site that was mentioned in the video. The unit is actually a gas turbine with an electric machine between a compressor and a turbine with a combustor chamber. During storage the electric machine is clutched to the compressor and separated from the turbine. Air is pumped into the ground for storage, and this is done when the grid load is light, usually at night and on weekends, while the cost of electricity is low.
For generation, the electric machine is clutched to the turbine and separated from the compressor. The compressed air from the ground is mixed with natural gas (the fuel) in the combustion chamber to develop the power for the turbine. The idea for this design was an economic one to save on the cost for burning fuel required for compressing the air of a conventional gas turbine.