A company that proposes storing and releasing energy with winches and weights in mineshafts is set to build its first demonstrator project in Scotland.
Edinburgh start-up Gravitricity has signed an agreement with Forth Ports to build their first demonstrator on land within the Port of Leith. Work will begin on the £1m project in October with plans to be operational by late December.
UK start-up eyes abandoned mine shafts for energy storage
The 16m high rig will use the port’s electrical network and grid connections and will be used to demonstrate the speed of response of their energy storage system.
Gravitricity’s energy battery works by raising multiple heavy weights – totalling up to 12,000 tonnes – in a deep shaft and releasing them when energy is required. They plan to roll out their technology in disused mine shafts globally.
The demonstrator at the Port of Leith will allow the technology to be trialled on a smaller scale, utilising an above ground structure.
In a statement, Gravitricity’s lead engineer Miles Franklin said: “This grid-connected demonstrator will use two 25-tonnes weights suspended by steel cables. In our first test we’ll drop the weights together to generate full power and verify our speed of response. We calculate we can go from zero to full power in less than a second – which can be extremely valuable in the frequency response and back-up power markets.
“We will then run tests with the two single weights, dropping one after the other to verify smooth energy output over a longer period. Together, this two-month test programme will confirm our modelling and give us valuable data for our first full-scale 4MW project which will commence in 2021.”
The lattice tower is being delivered to Gravitricity by Leicester firm Kelvin Power, with the winches and control system supplied by Dutch winch specialists Huisman. The company is also in discussion with Scottish businesses regarding the supply of other key components including the weights.
The Gravitricity project is supported by a £640,000 grant from UK government funder Innovate UK.
Really? Wouldn’t creating pumped hydro sites be more effective and much higher capacity?
Great news, this is a very good concept in an area where new technology is desperately needed.
Energy storage at the GWh level is very limited in the UK, and there are a number of serious safety issues surrounding batteries on a large scale.
Maybe they could be built into windmills!
I saw a demonstration by Mr Blair of Gravitricity back in 2018 and unfortunately we were not able to help fund the project at that time but I’m glad to see it’s finally making it to a prototype. The cables do require replaced occasionally.
To Mr Harbord’s question lifted and lowered weights has better end-to-end efficiency than pumped storage, requires a lot less infrastructure (abandoned mine shafts already exist, damming up valleys tends to be a large unpopular change to the countryside) and has faster response times.
Another great contribution to Grid level fast response storage. Has the use of rail guided weights on steep sided surfaces such as disused quarries etc been considered? Whilst vertical displacement is generally less, the system is highly scalable (e.g. using the whole side of a cliff face). Such a system should have significantly lower capital build and through-life maintenance costs.
I take your point, but I would have thought, with an ever increasing amount of electricity produced by renewables, we need large amounts of high volume storage. I struggle to see that this technique would ever have enough capacity to provide much overall capacity, even with multiple sites. So, I would have thought that it would be very good for cheap, fast response storage but never good for high volume storage.
I wonder if this could also be tried in Wales, where there must be many disused mines, although one wonders about their safety after long periods of disuse, or indeed whether many may have been filled-in.
Gravitricity are wise to focus on the niche frequency stabilisation market rather than time-shifting megawatt-hours. Anyone with a basic scientific background + access to the price of electricity at different times of day can quickly calculate the economics of the latter (hint E=m•g•h) and investors hoping to make a quick buck will rather be faced with … ahem … a long weight
Sorry if I am wrong but after a calculations for this (25 t ) mass and 100 m long falling the total energy that can produced will be around 680 W*h, even of 100 % utilization . Where is the reason and benefits and after how much years it will be profitable? Or I miss something important?
I much agree with Eklj. With big weights and cables. this amounts to quite heavy engineering , so therefore downtime for replacing the cables, attachments and also the motor/generators too, could be considerable and quite costly. However compared to maintenance of offshore turbines I’d estimate considerably less. I think the quite heavy duty cycles, especially kicking out high energy bursts may also be challenging. But much within the scope of current technology. All that said I very much like the concept and wish the company much success rolling this out to industry. I’m sure it can work well if engineered properly.
An excellent idea. This could be easliy adopted worldwide. Best of luck with the prototype testing
My students have been developing grain-silo sized flywheel energy storage systems (FESS), but I have to admit I like this concept even better. I think ‘the penny is beginning to drop’ about the serious disadvantages, toxicity and sustainability problems of bulk battery storage systems and (like FESS) this simple system could be used for decades without any loss of storage capacity or its very high efficiency. I’m sure the cost-benefit analysis of drilling several shafts in on place will also turn out most favourably – we should not forget suitable slope-drop sites too.
Krasimir – I believe the capacity of the demonstrator works out at 6.8kW/hr. If you work out the capacity for the maximum size envisaged (1500m drop – 3000t) that works out to roughly 12MW/hr – and that’s just for one shaft.
You are right, Mr. Richard, my mistake a digit place in calculation. I cover myself with shame!
But still have doubts about economic parameters. There will be around 90 % of efficiency in generator mode, similar in lifting mode, it will be lost of transformation in inverter, loses in mechanical part. So if there is a special purpose of compensate some short power demands in grid, maybe there have to provided some parameters for estimation. In pure storage purpose I think artificial water system.
(that can use the same mine structure) is more simple, maintenance profitable and need smaller investment. I also have doubts of result in multiplication or scale of mechanical system like this to achieve project parameters of 12 000t. There also will be issues with safety work and response time in meaning recover capacity of system after use it energy.
Anyway I will be glad to see positive results!
The world desperately needs to move beyond any and all technologies for “storing and releasing energy” which are, in truth, ONLY storing and regenerating electricity. The limited capacity of orthodox systems, PHES and CAES excepted, render them unviable other than for frequency response. The misguided investment in a gross over-capacity of RE will come back to haunt us.
(Disruptive) Innovation is no place for new business start-ups – when will we ever learn?
Von der Leyen said: “What we start to observe now is an un-levelling of the playing field in our single market. Therefore, in response, we need to support those that need it the most; we have to push for investment and reform.” Impoverished innovators need the most reform, support and investment!
The ‘playing field’ in R&I never has been ‘level’! BIG companies set the agenda and rule the roost.
“Brussels suspended the EU-wide state aid restrictions on subsidies to companies in mid-March to allow governments to prop up big companies.”
“The rules on subsidies are regarded as a fundamental part of the EU ecosystem, ensuring that governments cannot artificially support firms and ‘pick winners’ in the European marketplace.”
Innovate UK and our entire Innovation Strategy has always applied a draconian version of the self-defeating ‘technology neutral’ and ‘match funding’ principles that no other EU member state has ever imposed. ‘Winners’ are ‘picked’ solely on the criterion of the money they bring to the table.
Can we compare like with like in the comparison with a hydraulic system. The top tank of a 3000t system is only 44m in diameter if it is 2m deep. This must cost less than a 3000t weight. The other advantage of water is that you can fit it down mine workings and have a much bigger system. Cover the top reservoir surface with floating solar panels and you should have a lossless storage system.
Nice idea….. but not new by any means.
The concept has been around for a long time and even ‘back garden’ engineers etc have dabbled with building such devices. There are some similar small scale portable Lighting systems working on very similar gravity-based designs.
The main issue is that there are other companies developing similar approaches to utilising Weight-based designs such as rolling rail-based stock that essentially run on track running down steep or very long sloped mountain/hillsides. Some contain the Batteries on board to act as balast and extra energy as they roll down or are used to drive the equipment back up the track. So hopefully this answers Simon’s comment regarding use of quarries, hills etc.
The main, and probably only, advantage of either this, or any of the other systems, is that they should be viewed as a means to “decentralise” power supply; particularly to remote/rural areas. Given the rather VAST increase in likely electrical consumtion required to fulfil proposed future transmport electrification, as well as the large-scale reduction of fossil fuel based supplies; it’s therefore essential that more decentralised systems be established.
However, the killer is efficiency, or lack of it, as mentioned by Krasimir. As an innovator and Developer, my company has developed a gearing/transmission system that provides major benefits that could be useful for such systems; but I’m afraid there is little funding from areas such as Innovate for one-man or very small companies. It seems to be more of who you know than what you know when it comes to funding.
However, I hope the company well and hope they don’t fall into the trap of trying to Patent this or fall foul of those who think they can Patent such an idea – as I say, the idea is far from novel – in all it’s guises.
But, by all means install one locally to us to provide us with Off-Grid supplies – that would be beneficial.
I fully agree with David Smart that the only truly economic storage technologies for large scale usage are PHES and CAES and the massive over-investment in unreliable power generations systems (i.e. so-called Renewables) are storing problems for the future.
However, we now have this massive installed capacity of solar and windblown white elephants that produce power when we do not want it, (for which we pay £ 1 b / year anyway through the “balancing Mechanism”), and do not produce it when needed.
If these stores were built on land-based wind farms, these white elephant, would not cost us the crippling and increasing £ 1 b. year that we pay for power-availability, that we cannot possibly use. Personally, I prefer CAES for large scale storage.
So if a philanthropist provided the site rent- and rates-free, a group of volunteers offered to staff, run and maintain it for no pay and you achieved 100% round trip efficiency, over the past week by buying electricity for the cheapest hour every day and selling it at the most expensive time you could have earned between €15 and €42 per MW-h , average €24 per MW-h
https://www.nordpoolgroup.com/Market-data1/GB/Auction-prices/UK/Hourly/?view=table
Your 12 MW-h facility would therefore earn €288 per day – let’s call it a round £100k per annum. Hypothetically, if everything else but the capital cost were supplied for free – what is the payback? – the demonstrator costs £1 million!
I am curious as to the speed at which the weight (s) will drop. If the weight is a close fit into the mine shaft, will there not be a buffer of air below the weight? How will that be dissipated? Any possibility the dissipated air stream could be further used to provide additional generation? Interesting venture. Good luck.
Jack, your fantasy figure for what “we pay for power-availability,” is straight from the incorrigible (dishonest) FF advocacy playbook. Please study the actual, verifiable facts:-
https://www.sciencedirect.com/science/article/pii/S1364032118300091
Forgive me if I’m wrong, but haven’t you previously claimed that UK energy prices disadvantage us relative to Germany? The opposite is the case – check the facts yourself. Germany’s economy out-performs the UK too, by some margin. Brexit makes our economy less competitive. All we need is an engineering investigation where the acronym BGES comes top of the list.
Even if your £1bn/year were true, National Grid could pay that bill and still make a handsome profit. You are right, onshore wind is best, but the Tories threw a spanner in the works. The US does alright in making a broken market model work well enough. . . . (But they don’t like offshore wind!)
“The wind power boom has benefited consumers in regions where wind development is fastest, contributing to a 40 percent wholesale power-price plunge since 2008 in the Midwest, for example. Yet the surplus is creating havoc for nuclear power and coal generators that sell their output into short-term markets.”
https://climatecrocks.com/2013/03/13/renewables-changing-the-math-of-energy-grid/
As I told NG eleven years ago, the best (only?) location for storage is on/under water! That is why I advocate the combination of wind/wave and tidal power – Before-Generator Energy Storage isn’t a viable engineering option anywhere else. As I’ll explain again, til I’m blue in the face, the design is unique in tackling the problem of VRE from all three sides: It ELIMINATES intermittency AND curtailment and will also provide negative reserve for existing renewable energies, when they’re surplus to requirements. So, there would be NO problem, if NG had invested in storage R&I. The subsea Western Link is £1bn wasted, if offshore wind had the right integral energy storage.
theenergyst.com/western-link-failure-sees-national-grid-pay-31m-to-turn-off-wind-farms/
“Germany and Britain could learn from the design of each other’s balancing markets.” That’s a very bad joke. BGES would kill off both the balancing and capacity markets – result!! NB: Most of the world’s great cities and energy-consuming industry is near the coast and many potential tidal power sites will need flood defences anyway, within the lifetime of the generation born today.
There are so many different solutions but the storage requirements and locations are so very different – one size very definitely doesn’t fit all! My students’ FESS solution was optimised to support an Indian rural village of about 200 people. Our fundamental aspiration in every case, however, is to minimise the long-term environmental, maintenance, toxicity and sustainability impact of any solution adopted and in virtually every case that ruled out the use of the increasingly popular bulk-battery storage systems.
David – agreed, but I believe most people on this site will know the potentially disastrous consequences of Germany’s current energy policies.
Replying to David Smart’s criticism of both my common-sense and knowledge of power engineering I would point out that his reference source (Science Direct) is a totally biased, policy-driven web-site: i.e. ultra-high spin-rate. I prefer to get my info from OBS, ONS and the Eurostats. The OBS / National grid both publish figures for the “Balancing Mechanism” and both state that this exceeds £ 1b/ y and is increasing as the percentage of “unreliables” increases. The subsidy that we all pay for renewables is about £ 11 b /year.
The subsidy for renewables is a carbon tax on everyone, including UK industry to provide new power plant which is inferior to that being replaced in every respect except CO2 emissions.
The balancing mechanism is purely paying unreliable generators when their power cannot be used, which totally distorts UK generation costs. The Eurostats show clearly that German industry has lower power prices than the UK: (they have higher domestic prices).
Hi Jack
I did feel that the (fantasy) criticism was harsh and I do suspect that base-load suppliers having to bid into a market focused on short term (day ahead?) trading is somewhat dubious.I would anticipate that a fortnightly term would be better, in the UK, as it would take account of weather patterns that can be deleterious to power supply.
I should say that I, myself, believe that CO2 reduction is important but worry about subsidies – especially as to who pays and if they are hidden.
I am uncertain if suppliers have to pay for power they fail to deliver or if they are capped if power is in excess.
Moving costs around (and pricing) seems to be a way big companies can get more out of the customer, whilst supplying less value.
Just to confirm. You are saying that, in Germany, the domestic customer is paying the subsidy and not the industrial customer?
This like uranium flywheels provides the necessary momentum to maintain frequency long enough for more lasting sources of power to ramp up when the battery banks can’t cope. At the moment of crisis, this can be a strong support to the system. However, the amount of energy stored is trivial. There would have to be a PPA that reflected it’s value as a standby resource that would almost never be used. A use for depleted uranium. I looked at oil wells for this. The casings are usually still in good nick unlike older mineshafts and the depths can be substantial. The limitation becomes the thickness and number of cables required to support very heavy weights.
As a rider to my own comment. Many mineshafts and oil wells are flooded so the height available can be limited. The number of viable sites is limited but even so, a less resources consuming option than keeping Drax on spin generate.
Philip – yes – good point – but my house on Dartmoor is on the site of a disused copper mine pumping station so that consideration would have to be taken into account in the cost-benefit analysis when considering a shaft for gravity energy storage. Old gold mine shafts in places like South Africa might be dry all the way down.
I would like to explain to Jack, that my remarks on May 15 were rather rushed, in response to the unscientific, emotive language he uses. (white elephant – crippling costs etc.) When my comment wasn’t published on Friday, I posted a correction, which The Engineer hasn’t printed. If you care to read the (unbiased) Science Direct review, you will see a figure for “BSUoS charges”, but I should point out that this covers a great deal more than “power availability.” (I think ‘Climate Crocks” is more likely the site you don’t trust and never visit?!)
After initially making an inexplicable error in checking out Jack’s figure of £1bn/year for “power-availability” – better ‘known’ as “BSUoS charges” (which recover all system operation costs) – I see the actual cost was £1,207m in 2016. ref: 3.5.2. Britain. (posted 16/5/20)
You can’t justify accusing websites that disagree with you of “policy-driven spin” when their data is verified by multiple sources. If the UK’s subsidy schemes ramp up the ‘strike price’ on new power installations (New nuclear £92.50/MWh. New offshore wind £40.00/MWh.) you can blame the government’s blinkered ‘market’ strategy for that. If the state had invested in innovation the way the CEGB used to, these problems would have been solved years ago. They don’t have ANY strategy to develop the capacity of energy storage required – there’s NO ‘market’ solution for that.
Yes Richard, most people on this site (and in Germany!) would prefer to see an extension to the life of nuclear plant, rather than mining and burning brown coal. Perhaps the EU can bring in some innovative new subsidies in a Green New Deal to hasten the end of coal (in Poland too)?! The fools should have acted on the advice I submitted to the consultation setting up Horizon 2020.
Responding to Julian: several subsidies are guaranteed to all operating windfarms. Originally this was to stimulate the investment, but, has carried on for years since that was a justifiable seeding fund. “Renewables” based generators are guaranteed a price of around £140 / MWh for the power they produce (Current reliables-based generating costs are below £ 30/MWh). A second subsidy is the so-called “Constraint Payment” this is a payment if the generator has capacity that is not usable by the grid; this subsidy, according to the OBR is £ 1.1 b this year out of a Renewables Levy (for which read subsidy) of £ 11.8 b. This is a unique and totally wasteful subsidy, in that it merely penalises carbonaceous fuels. The “Carbon tax” is a virtue signal that makes no significant difference to the growing carbonaceous fuel usage in the world.
Jack, you are living in the past, quoting figures that are a historical accident of bad governance, based on discredited ‘market’ manipulation (FiTs, RoCs and CfDs). Subsidy-free windpower is now on the horizon. Your complaints expose UK political incompetence, not the shortcomings of RE technology, which other countries like Spain manage better and benefit from.
The sensible adoption of large-scale energy storage will transform the economics of marine RE and put coal and gas out of business on cost, not just environmental necessity. If we invest BIG in better innovation the rest of the world will follow our lead. Your denial of the proven science is not setting a good example to our young (or old) engineers. Stop it, right now. Your ‘signals’ have no virtue.
The recent government approval of investment by Drax prepetuates past (gas) economic errors.
“If you thought that prices for industrial use electricity and gas in the UK were expensive, think again.” UK . . 8.794 pence per kWh. Germany . . 9.891 pence per kWh. For gas: UK . . 2.594p/kWh. Germany . . 4.097p/kWh.
http://www.businesselectricityprices.org.uk/europe/
A greater difference on domestic electricity:- UK – €0.2122/kWh. Germany – €0.3088/kWh.
https://ec.europa.eu/eurostat/statistics-explained/index.php/Electricity_price_statistics
If ‘expert’ statisticians offer conflicting data, confirmation bias has too great an influence.
Personally, I’d put all my eggs in this basket. . .
https://www.powerengineeringint.com/world-regions/europe/worlds-first-power-to-x-to-power-hydrogen-gas-turbine-demonstrator/
. . . except that VRE needs to be stored BEFORE it’s fed into the grid, in order to smooth variation, generate flexibly and eliminate curtailment. Then, at the other end, only biomethane (AD) should be added to the mix. FF must be phased out quickly through managed decline of the industry.