Aug 18 2017

A New Option for Grid Storage

Last year I wrote about the various grid energy storage options, adding a newly proposed option – chilled air. I am now writing to add another new option to the list – concrete gravity trains. But first, let me review the background.

We need massive grid storage for two main reasons. The first is peak shaving. Energy demand peaks in the early evening, which means we need to have the capacity to meet all of peak demand, even though demand the rest of the day is lower. Peak power is less efficient and clean, because the more efficient energy is used preferentially for baseload production. We dip increasingly into the less efficient energy options when necessary to meet peak demand.

Grid storage could shift energy produced during low demand and then draw upon it during peak demand. Optimally enough grid storage could completely flatten power production, increasing overall efficiency.

The second reason for grid storage is the increasing use of renewable energy sources like wind and solar which are intermittent and not on-demand. This varies by season and location, but generally peak demand occurs just after sunset, when the sun is not shining. No matter how much solar and wind energy we produce, without grid storage we would need to maintain all of our peak capacity. You can encourage people to shift their energy use to times when energy is produced, but it’s hard to get everyone to do something.

The bottom line is that if we ever want to get to significant renewable energy production we will need significant grid storage. 

Grid Storage Options

What are the features that make for good grid storage options? The most important is probably efficiency, sometimes called round trip efficiency – how much energy is lost when converting generated electrical energy to its stored form and then back to usable electricity? Other features are also important: how many cycles can the system last, what is it made out of (does it use rare, expensive, or toxic material), are there any safety issues, how big and heavy is it, and are there any limitations as to location or terrain, are there any environmental issues?

Batteries – Many people first think of batteries as an option for grid storage. They are potentially a decent option. Their efficiency is 60-70%, which is not the best but is good enough. Their capacity is relatively low, however, and their main limitation is charge-discharge cycles. Use of rare or toxic materials is also an issue. For grid storage options size and weight are not an issue.

Pumped Hydro – This is currently the most efficient option in widespread use, at around 80% efficiency. Essentially hydroelectric plants will pump water from lower to higher elevation during times of excess energy production and then use that water to generate electricity during high demand. This is the best option for locations that have good water reservoirs and terrain that allows for significant elevation differences. This is not an option for flat or very hot and dry areas (evaporation is a source of inefficiency).

Compressed air – Use energy to compress air in a chamber or tank, and then decompress the air when needed to turn a turbine and generate electricity. The big disadvantage of these systems is their low efficiency, around 45%. This is a deal-killer, in my opinion, despite the fact that other features are good. There is no limit of cycles and no special materials are needed.

Flywheel energy storage – Use energy to spin up a flywheel to high rpms (like 50,000), then use the kinetic energy to generate electricity when needed. Systems using mechanical bearings have a 50% efficiency, which is not great. Optimal systems using magnetic bearings in a vacuum claim 85% round trip efficiency, higher than pumped hydro. Efficient systems require use of material with high tensile strength to get up to high rpms. They get more inefficient over time, as the wheel slows down and loses stored energy. They can be charged and discharged quickly but overall capacity is relatively low. In general it seems these systems are useful on a relatively small scale but it will be difficult to use them for massive storage.

Hydrogen – You can store energy in hydrogen by using energy to split water into hydrogen and oxygen, then getting the energy back by burning hydrogen with oxygen. This is basically a hydrogen fuel cell. The big disadvantage for hydrogen is that is has a 30% round trip efficiency, which is very low.

Chilled air – You can use energy to chill the nitrogen in air to liquid nitrogen, which is then stored. When energy is needed you let the liquid nitrogen heat up, it then turns into a gas and the expanding gas can be used to turn turbines and generate electricity. This is a novel idea that uses air as its main component, but has an efficiency of about 50% which is not great.

Concrete Gravity Train – This brings us to the new option – a California company, Advanced Rail Energy Storage System (ARES) built a test system in which they store energy by rolling a train up a track. The train is mostly a huge block of concrete. When energy is needed you let the train roll back down the track, and use regenerative braking technology to generate electricity.

They claim 80% efficiency, which is the same as pumped hydro and is great for grid storage. The current system uses a 9.2 kilometer track with a grade of 7.2%, which they found to be optimal. The full system can provide a maximum of 50 MW of power, but only for a short period of time (on the order of 15 minutes) or less power for longer.

One limitation of this system is that you need a location that allows for a long track at a relatively steady grade, so it is highly location specific (like pumped hydro). This will be a viable option in some locations, such as Nevada where the current system is being developed. It is still not an option for locations with a flat terrain.

I did have a similar idea for energy storage and I wonder if it is practical from an engineering and efficiency point of view. Imagine a vertical tower with cables or poles up which heavy plates of iron or lead are lifted using excess energy. When energy is needed the heavy plates are allowed to fall, generating electricity as they do. Their descent is slowed either mechanically by turning a turbine or electrically by regenerative braking. Such a system could be built anywhere, out of common materials, and could have a high capacity. The only unknown to me is the potential efficiency.

Of course, this is a simple idea and many other people must have thought of it also. I did a search to find out what is out there that uses a similar idea. I found a gravity power energy system that uses a similar idea – hydraulics are used to raise a very heavy piston up a shaft. When power is needed the piston falls, which forces water through a turbine and generates electricity similar to pumped hydro. Rather than using a tower for the vertical height they use a deep open pit mine. This system is similar in that is uses a vertical system to raise a heavy metal weight against gravity to store potential energy.

They claim the same efficiency as pumped hydro, around 80%. If so this may become my new favorite option – it is efficient, has high capacity, can be build anywhere, and has a low environmental profile. They currently have a demo plant under construction in Bavaria. We’ll see how it goes.


Note: The article was corrected to the proper total energy storage of the system.

40 responses so far

40 Responses to “A New Option for Grid Storage”

  1. MWSlettenon 18 Aug 2017 at 8:48 am

    This is a smaller-scale implementation of your idea:

  2. SteveAon 18 Aug 2017 at 8:50 am

    Holy cow. Best opening para I’ve read in a long time.

    It’s such a simple idea. All the benefits of hydro, without the hydro.

    With regards to the vertical drop concept, I’ve seen something similar in action for radios in impoverished/remote areas without easy access to batteries. You essentially hoist a weight on a long cord over a high tree branch, and as it slowly falls to the ground, it pulls the cord, which winds a little generator that keeps the radio going.

    Nice irony in the use of a mine shaft.

  3. SteveAon 18 Aug 2017 at 8:52 am

    Cross posted with MWSletten – nice link. Pretty much the same concept as the gravity radio I mentioned…

  4. fbrosseaon 18 Aug 2017 at 8:59 am

    Hydrogen could potentially some more interesting uses that could increase the 30% you quoted. First, the production can be increased by using the Copper Chloride Cycle. This is only useful for power generation that produces steam or industries with waste heat. This method of production requires lower voltage than for standard electrolysis.

    Though the scope of the article is specifically for storing electricity for peak power use, hydrogen production is a major contributor to CO2 for fixing hydrogen and hydrocracking procedures, as the easiest source of nitrogen is methane. Some improvements are possible there.

  5. bk1220on 18 Aug 2017 at 9:00 am

    Steffes Corp. has developed a system that uses our home water heaters as batteries (see, e.g., US Pat. No. 8,805,597)

  6. Nidwinon 18 Aug 2017 at 9:35 am

    First time I hear or read how grid storage is being done, interresting.

    What could be worth thinking about is when using the storage to generate electricity to not have one way to produce electricity but multiple ways one after each other. Or to have a mechanic that also partially store again an x amount of energy again while producing.

  7. Daniel Clementson 18 Aug 2017 at 10:21 am

    The vertical weight system has been powering clocks for many centuries.

  8. michaelegnoron 18 Aug 2017 at 11:38 am

    Why no mention of nuclear energy?

  9. DisplayGeekon 18 Aug 2017 at 12:07 pm

    Mr. Egnor…

    I can’t believe I have to answer this question. They say that there are no dumb quesitons… but you proved that wrong.

    Nuclear power is NOT a grid storage system, which is what this post was about. I’ve never heard of any nuclear tech that allows one to put the nuclear genie back into the bottle. Nuclear is a primary source, not a peak source, of energy… and as such was NOT the topic of discussion.

    I’ve been lurking for years before recently begining to comment here. I’ve seen your comments for quite a while… But in all of that time, I can’t recall you actually ADDING to the value of the conversations. As before, your comment here is what would appear to be an example of JAQing off. At long last sir, have no shame?

  10. RickKon 18 Aug 2017 at 12:38 pm

    Wow, what great timing. I just saw this minutes ago and marveled at how perfectly it describes Michael’s politics and his character as he presents it here.

    And yes, Geek is correct – there was no mention of nuclear for the same reason there was no mention of coal or oil or natural gas. That’s not what the article is about.

  11. pandadeathon 18 Aug 2017 at 12:47 pm

    To add to the previous response:

    A primary source of power is a process that is irreversible, it goes only one way and generally not highly controllable. For example the burning of nuclear fuel, you have to produce a steady and relatively high amount of energy for long periods of time. You don’t have a high amount of control over adjusting the power output at different times of day. You designed a plant to produce X Mega watts of power and it will steadily produce that amount of power. Another example would be solar. You collect the energy from the sun and you don’t have control over how much and when you get to collect the power. Even something like coal is hard to control the exact outputs. It isn’t easy to just burn more coal during peak and less during downtimes.

    So secondary grid storing options are very helpful. This means the primary source can produce either a steady stream of power, like nuclear, or an intermittent source of power, like solar (preferably several sources) and a Certain portion of that power goes into the secondary source. The secondary source needs to be highly controllable. Something that can be activated in response to power demands or even planned for certain times of day. The mechanical energy conservation is very helpful here. The primary source energy is converted to a form of potential energy which can be actively converted to kinetic energy at will. (To produce electrical energy, that kinetic energy of a turning loop in a magnetic field induces AC current.)

    Hopefully that helped a little.

  12. RickKon 18 Aug 2017 at 1:45 pm

    This post’s summary of the relative efficiencies of different storage methods is very useful and interesting.

    Have just started the Great Courses “Science of Energy” series – it starts with a summary of the “units problem” – the morass of units used to measure energy. Reminiscent of several discussions on SGU. Will see how the course handles the grid storage issue.

  13. tder2012on 18 Aug 2017 at 4:19 pm

    Interesting California is mentioned as their peak demand is usually at least 35 gigawatts (with about 1/3 is supplied by natural gas, 1/4 by imports), which occurs in the evening, as on can see on these daily reports Considering global storage capacity today is about 165GW (approx. 98% pumped hydro) I have to agree with the title of this article “Batteries Need to Get Big—Like, Enormous—for Solar Power to Shine”

  14. neuzelaaron 18 Aug 2017 at 5:05 pm

    The basic physics of the gravity train just does not add up. Information is limited, but enough for a skeptical look: A 9.2km track @ 7.2% grade means a 662meter (2171feet) altitude difference. The potential energy of a massive 300 tonnes rail car at the top is 300000*9.6*662 = 1947456Kilojoule = 541kWh. Over 8 hours that is 67kiloWatt, not 50MegaWatt as in the above article.
    To put that in perspective: The average US household needs 900kWh per month. So we need a lot of rail cars to put a dent in grid storage needs. To put it in yet another way: the electrical energy in one big rail car is equivalent to only 10 Chevy Bolt EVs with 50kWh batteries each.
    To put a true dent in energy storage needs we need Gigawatts, not Megawatts and certainly not kilowatts. Pumped Hydro storage plants store 10-30 MegaWattWour of energy. 10MWH is equivalent to ~20,000 big gravity train cars (!!). To generate a very modest 540Megawatt, and the train travels 9.2km/h, we would need at least 1000 big rail cars running down simultaneously. But since a rail car is ~17 meters long, only 514 would fit on a 9.2km track simultaneously.
    And then we have not even looked at the cost and practical aspects of putting down the rail tracks and emplacement infrastructure along mountain ridges. You can expect the big rail cars with built-in generators to cost at least ~$250K each. If they make 1 cycle a day and are written off over 25 years, the rolling stock cost would be at least 5c/kWh. But the bulk would be in writing off the cost of the track, land and system.

  15. davidron 18 Aug 2017 at 5:37 pm

    Neuzellar, I made some similar calculations and came to the same conclusion. Suppose I drill a hole in my backyard to create a gravity well, how big does it need to be to store 24 hours worth of energy. Turns out I roughly need a 100m deep hole big enough to fit a 100 tonne mass (or 1km deep hole with 10 t mass etc). Not very practical.

    Modern lithium batteries have a round trip efficiency of 90%, not 60-70%. They are easily scalable to meet diffferent applications. And like PV solar, they are also on a steeply reducing cost curve as manufacturing volumes increase. Which technology will win this race is already very clear.

  16. Alex Simmonson 18 Aug 2017 at 10:16 pm

    50MW is possible – the train just has to be heavy enough and go downhill fast enough. The duration it can deliver such power is limited though.

    Say 50 cars @ 300,000kg = 15,000,000kg x 9.81m.s^-2 = 1.47×10^8 J of gravitational potential energy per vertical metre.

    Power = dE/dt

    So for 50MW we need the 50 car train to drop at a rate of 5×10^7 / 1.47×10^8 vertical metres per second
    = 0.340 m/s

    There are 661 vertical metres, so a 50 car train could deliver 50MW for 661/0.340 seconds = 1945 seconds or about 32.4 minutes.

    The 50 car train would be moving along the tracks at 9200/1945 m/s = 4.73m/s = 17.0km/h ~=10.6mph

    Since a 50 car train is ~850 metres long, then the available 9.2km track is shortened by nearly 10%, so the available time at 50MW reduces from 32.4 minutes to about 30 minutes.

    Of course this all assumes 100% of gravitational potential energy is converted to electricity, so to get 50MW output the speed needs to be faster and the available duration shorter, how much faster and shorter depends on the efficiency conversion factor.

    I’ve no idea of the engineering reality of safely managing a 15,000 tonne train rolling down a 7% hill at 17km/h.

  17. Kestrelon 19 Aug 2017 at 12:19 am

    Egnor, actually nuke plants are trying to figure out what to do with excess energy as well. Older nuke plants don’t follow load very well, and get penalized for putting excess energy on the grid when variable generators like wind and solar are at peak production. I’ve seen some proposals similar to what Steve has laid out. Others involve directing excess heat from nuke plants to industrial purposes, like desalinization or fertilizer production. Unfortunately, nuclear reactors don’t generate high enough heat (safely) for many industrial purposes, but desalinization looks promising.

  18. tder2012on 19 Aug 2017 at 8:02 am

    This five minute read shows the serious limitations of grid scale storage, due mainly to very low power density. “Sort out your source of energy and take particular care before storing it” (a pdf file that automatically downloads with this link)

  19. BaSon 19 Aug 2017 at 2:38 pm

    At first blush, a vertical tower seems obviously better to me. But then I think about adverse conditions such as wind.

    You’re putting a giant weight at the top of a narrow spindly support building. In flat places where the train can’t work, where coincidentally there are a lot of tornadoes. So at a minimum you’d have to build in a system to safe the load quickly in anticipation of adverse weather. But it’s harder than just dropping the weight: you have to cook off all that energy of it dropping and braking as heat now, which means you need to build in some kind of megawatt radiators which would use … yep, back to tons of water again.

    I’m not a civil engineer but this seems like a non-trivial “gotcha” to the vertical weight tower plan.

  20. BaSon 19 Aug 2017 at 2:44 pm

    Let’s combine the ideas: I wonder how tight a spiral you could use for one of these tracks?

    Envision one of those kids’ marble tracks built in an ascending helix, but scaled up to giant size and using regenerative train cars instead of marbles. Then you could have a wide and squat structure (relative to the naive high weight tower) with tons of helical track. This would be safer against adverse weather conditions. You still have to contend with like, earthquakes though. And you aren’t getting the structural advantage of having earth and rock right under the track, you’d be building more like a power high-rise. But it feels more like the kind of problems that are well solved already by structural engineers for human-use skyscrapers.

  21. BaSon 19 Aug 2017 at 2:47 pm

    Also you could use all the interior space of the helix advantageously, since it would already be a tallish well-supported building structure. Who wouldn’t want to have offices in the power tower and see the train cars chug by their window on the way up or down!

  22. michaelegnoron 19 Aug 2017 at 6:17 pm

    I didnt say that nuclear was a grid storage system. It is a clean, cheap and essentially renewable source. Steven mentioned wind and solar but neglected nuclear.

    A good “skeptic” would denounce the anti-science hysteria against nuclear power, and not self-censor to please the eco-loons.

  23. Rburkon 19 Aug 2017 at 7:07 pm

    You can keep nuclear going all day long, so grid storage is not as important as for it. When wind, sun, and other interment energy sources require more grid storage. That is probably why Steve didn’t consider it in his list Micheal Egnor.

    It’s not that grid storage is not important for say nuclear it would just be more important for taking better advantage of solar and wind energy that is available in a certain area.

    The real interesting thing is how you can read minds through blog post to know that Steve is somehow self-censoring?

  24. Alex Simmonson 19 Aug 2017 at 7:24 pm

    michaelegnoron – Steve didn’t mention nuclear power (or coal or gas) while at same time mentioning solar and wind because of any bias against nuclear, but rather because this was about *energy storage*, a complementary technology for *intermittent energy production* technology that may not be producing power at the moment you need it.

    Nuclear (and coal and gas) are sources of *continuous energy production* which can be ramped up and down (within reason) to meet variations in power demand and hence are not relevant to a discussion of energy storage technology used to complement intermittent energy production technology.

    Energy storage technologies, the topic of discussion, are explored assess their potential to make intermittent sources of power production more useful, effective and/or potentially more economically viable.

  25. RickKon 19 Aug 2017 at 8:40 pm

    Egnor said: “I didnt say that nuclear was a grid storage system. It is a clean, cheap and essentially renewable source. Steven mentioned wind and solar but neglected nuclear.
    A good “skeptic” would denounce the anti-science hysteria against nuclear power, and not self-censor to please the eco-loons.”

    Are you just trolling, Michael, or did you simply not understand what Steve wrote?

    Now, take your time, go back and read Steve’s post again. He mentioned wind and solar because they are “are intermittent and not on-demand”.

    Michael, what about nuclear power is “intermittent”?

    Stop hearing the narrative you want and try reading what people actually write.

    Unless of course your goal is simply, as Bill Maher says in the link I posted, to provoke people who are trying to have an adult conversation.

  26. Kestrelon 20 Aug 2017 at 12:55 am

    Would just like to add that nuclear is not really a viable option for the future US energy portfolio. New developments are prohibitively expensive, take decades to complete, and the history of the industry is littered with bankruptcies, failed projects, safety issues, and prematurely decommissioned facilities. It’s a complete cluster. And I work in the industry. No rational company wants to get into that game, and for good reason. The US is *not* ready to run nuclear plants economically or safely. Other countries can do so largely because of massive government subsidies/ownership, or because we actually don’t know what safety issues they’ve rectified (Russia historically has been a major offender here, but China could be next. We’ll actually never know).

    Here’s what the next decade of energy generation will look like in the US: a declining production from coal and nuclear. Much more natural gas production. Probably a continued expansion of wind and solar, despite the political regime. Grid storage is the only practical way to satisfy the disadvantages of wind and solar. Maybe flow battery is the most promising at this point, but it’s hard to say. One size will definitely not fit all.

  27. Kestrelon 20 Aug 2017 at 1:20 am

    One more thing – nuclear is not “clean” “cheap” or “renewable.” Those are industry falsehoods. Uranium mining is messy, irradiates a lot of water in a lot of third world countries, and has a substantial carbon footprint. Presently, the carbon footprint of the nuclear industry (including mining, enrichment, fabrication, construction, operation, and decommissioning) is less than fossil fuel alternatives but much moreso than wind or solar. Estimates vary and it’s difficult to quantify. But as high grade uranium mines dry up (and there are few. We haven’t discovered a new high grade mine in decades) the overall energy put into mining and enriching uranium fuel rods will lead to a higher carbon footprint than natural gas by, some estimates predict, 2050. I think it’ll be sooner, based on the expansion of nuclear developments in Asia.

    There are ways to mitigate that. We could adopt breeder technologies to produce fissible plutonium from natural uranium. Breeder reactors are extremely complex and have a sordid history of failures, sometimes life threatening. It’s a non-starter.

    We could also ramp up reprocessing of spent fuel rods. Both this, and breeding, in my estimation, have frightening ramifications from a nuclear non-proliferation standpoint. Both processes create a small amount of weapons-grade plutonium that simply slip through inventory. They can’t be accounted for. Someone could nab enough plutonium from a reprocessing plant or a breeder reactor to build one nuclear bomb *a month* and nobody would ever notice. And that’s just from friendly countries. Now imagine a country that *wants* to build a bomb, with nobody noticing that they’re doing so.

  28. BillyJoe7on 20 Aug 2017 at 4:32 am

    Michael Egnor:

    “Steven mentioned wind and solar but neglected nuclear….A good “skeptic” would denounce the anti-science hysteria against nuclear power, and not self-censor to please the eco-loons”

    From here:

    “Many experts think that if we are going to rapidly wean ourselves off coal we will need to build more nuclear plants. Even with the negatives of nuclear in terms of waste storage and cost, it is still far better than coal. We should prioritize the development of next generation nuclear power plants that produce less waste, and may even be able to burn the waste of older plants. We can also develop thorium nuclear power plants”

    Guess who was the first to comment?

  29. Robneyon 20 Aug 2017 at 10:33 pm

    @ Egnor,

    I don’t want to speak for Novella, but as a regular reader of his blog, I’m fairly confident he has several times acknowledged the need for nuclear energy as a bridging technology towards a renewable system.

    I’m not convinced because the upfront capital costs, difficulty in securing private finance/insurance, and long lead times in building nuclear generators does not make nuclear a very viable proposition.

    I’ve actually got no objection to nuclear energy in principle – but even if we commissioned a load of nuclear power stations today, by the time they were online, the energy sector will likely look very different, which makes them a bit of a risk and perhaps not the best investment.

  30. Steven Novellaon 21 Aug 2017 at 8:56 am

    Unfortunately I think the time to build nuclear power plants was 50 years ago. It is ironic that the environmentalists who were anti-nuke have put us in a situation where global warming is more of a threat because of our waning nuclear power infrastructure.

    It may be too late to build any serious nuclear power at this point, but I don’t think that is clear. Sure, things will be different in 30-50 years, but we don’t know exactly how. We may not come up with a viable massive scale grid storage solution in that time, limiting the utility of intermittent power sources. Therefore, there may still be a need for large scale baseload production, and nuclear is a good option for that – better than any fossil fuel option.

    I think what we need is a major development program to figure out how to build next generation nuclear plants, and maybe even thorium plants, that are safer, do not create weapon’s grade waste, and can be built more quickly. I doubt this will happen, but it should.

  31. neuzelaaron 21 Aug 2017 at 11:25 am

    The article in “Interesting Engineering” contains several glaring errors that cause gravity storage to appear 1000X rosier than it actually is. Unfortunately those errors were repeated in the latest SGU podcast, and in the above article where Steve writes:

    “One 300 ton car can provide 50 MW of power for 8 hours while rolling down this track.”

    That is false, off by three orders of magnitude. Basic physics (M*G*h): One 300 ton car provides at most 0.067 MW of power for 8 hours. The energy in a single 300tons train car is similar to the energy in a tank of gasoline in the average car (0.5MWh). That is not much.

    The planned Nevada Implementation of the gravity train stores a tiny 12.5MWh of energy in 7 trains of 9 heavy cars eachs (total 9,280 tons of weight over a 610m/2000-ft altitude differential). Therefore the rated 50MW peak output power can only be sustained for 15 minutes tops before all cars are at the bottom. That 50MW is not much: most pumped storage facilities are 1000MW and up.

    Even more problematic is the cost. The project is $55M with an expected lifetime of 30 years. That works out to whopping 36 cents per kilowatthour. For comparison: Li-Ion battery grid storage costs roughly 13 cents per kWh over their lifetime, with the added advantage of lower losses (>85% efficient) and much smaller land use. Since the technology for the gravity train conventional there is little hope of cost reduction over time.

    Except for powering grandfather clocks, gravity (train) power makes little sense because the energy density is simply too low. Just like ‘Solar Friggin Roadways” this is an idea that looks appealing to many on first sight, but doesn’t survive a second look with calculations using high school physics.

    The technical spec of the ARES Nevada gravity train project is here:

    The flawed Interesting Engineering article that was referenced by roques in the latest podcast:

  32. tgeatonon 21 Aug 2017 at 6:01 pm

    I was excited to hear your idea about the vertical storage @Steve– I’ve had a similar idea for some time since I heard about the hydro-storage systems. My idea was for urban buildings to make use of existing elevator shafts to store energy that they might collect from solar cells. Rather than sell excess energy back to the grid, individual buildings could story potential energy by lifting a large weight up an retro-fitted elevator shaft. My wife is an architect and informed me that a heavy weight high in a building might cause stability issues, especially in earthquake scenarios, so perhaps this would not be feasible. What I liked about this idea though is that there are already existing elevator shafts that could be retrofitted to this task, and so might be relatively cheap to create. At the very least they would be interesting pieces of public engineering.

  33. tder2012on 21 Aug 2017 at 6:31 pm

    Steven Novella, I agree with most of your statement. Today’s modern societies require 24-7-365, dispatchable, synchronous electricity generation (also on-demand) and nuclear can meet all these requirements. The other point about nuclear, that the USA’s National Renewable Energy Labs writes about here, is that nuclear can also be used to replace fossil fuels for some industrial heat processes Today’s nuclear reactors can be built on time and on budget, as this South Korean build in United Arab Emirates shows (need much more of this) . There is interest in R & D of advanced nuclear reactors in Canada as this overwhelming response to Canadian Nuclear Labs Request for Expression of Interest shows There is still hope for USA with initiatives like Nuclear Innovation Bootcamp and of course China and India see a future for nuclear power.

  34. MosBenon 22 Aug 2017 at 1:41 pm

    If Egnor really had any care about seeming like a reasonable, rational commenter, this would be the perfect post for a contrite apology and recognition of being wrong. As others have said, the article mentions solar and wind production and not nuclear because solar and wind have the problem of being intermittent and not always matching up to the demand needs, thus making some kind of energy storage option intriguing. Nuclear power doesn’t have that problem; it creates lots of power whenever the plant is running. Storage would still be nice because the nuclear plant would produce lots of off-peak energy, but it’s not a problem in the same way that it is for solar. And that’s clear in the article, but Egnor wanted to try to score some cheap digs at Steve so he wrote two posts that completely miss the point of the article.

    While it’s hard to believe that it was an accidental misreading of the post, Egnor could at least somewhat credibly claim that it was a mistake and that Steve was right. That would at least buy him a little credibility for the next post in which he lodges complaints. But he probably won’t do it because he’s overcommitted to the idea that Steve, and skeptics in general, are closed minded ideologues.

  35. MosBenon 22 Aug 2017 at 1:47 pm

    As for nuclear power, I think that there was reasonable cause to be worried about the safety of nuclear power as it existed in the middle of the 20th century. That generation of plants really did produce problematic waste and contained the risk of meltdowns. Were they worse than burning coal? Probably not, but I’m not sure that things would have been super wonderful if we built a ton more nuclear plants, if only because it seems like we’d probably have had a similar rise in catastrophic plant failures, and who knows what downstream effects adding several more Fukishima-style disasters does? Ultimately, when climate science started to coalesce in the late 70s, into the 80s, and definitely by the 90s we should have been putting tons of effort into researching newer types of nuclear plants to see if we could build safer, less expensive plants, as well as really pushing for the adoption of renewables. Instead, we did almost nothing, and then continued to do almost nothing through the 00s. It wasn’t the lack of nuclear plants that was the biggest driver of getting us to where we are today, but several decades of denying that there was even a problem to be addressed, primarily by one of the two political parties in the US.

  36. Survivalist13on 22 Aug 2017 at 4:38 pm

    You’ve missed an option, similar to the chilled air but the other way, heated air storage.
    The thermodynamics are neat and should allow good round trip efficiency, for low cost and scale-ability.

    As other people have mentioned in regards to gravitational energy storage using a tower, the expense of building a tower strong enough would be far too high. Pumped hydro is only cost effective because the hill already exists.

  37. MosBenon 22 Aug 2017 at 5:55 pm

    Can someone explain to me the feasibility of moving energy around? Several comments seem to assume that if we were to build a tower for gravity-based storage that it would need to be located in the Midwest, and that therefore tornadoes would make it impractical. But what’s stopping us from building the towers on the Eastern side of the Rockies and in Eastern areas with lots of old mining areas and then shipping the power to the Midwest? I assume that there’s some amount of energy lost as it travels along transmission lines, but it is so much that it’s really not worth doing? Is there some way to have each region of the country install whichever power production and storage makes the most sense for that area and then share the excess with a nation-wide grid?

  38. michaelegnoron 25 Aug 2017 at 10:34 am

    [[But he probably won’t do it because he’s overcommitted to the idea that Steve, and skeptics in general, are closed minded ideologues.]

    Where would I ever get that idea?

  39. RickKon 25 Aug 2017 at 10:42 am

    Well Michael, once again you made a mistake. You let your pre-determined narrative drown out what Steve was actually talking about. And when called on it, you vanish and return days later just to snark.

    Dependable as the tides.

    Your only engagement is to provoke people who are trying to have a conversation.

    Now we’ll see how you decide to troll Steve’s very reasonable post on nuclear waste. I can’t wait to see whether you respond to your own internal narrative or to what he actually wrote.

  40. MosBenon 25 Aug 2017 at 12:37 pm

    Michael, for crying out loud, can’t you just admit that in this instance you were wrong? Go ahead, maintain all of the annoying straw men that you bring up in other instances (survivors survive, sigh), but here, in this post, you were wrong. Nuclear power, and whether or not Steve supports it, is irrelevant to the post. Everyone sees this, and you almost certainly see it as well. Just once, say that you were wrong and then go back to your normal nonsense.

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