The Anonymous Widower

Gravitricity Gets An Imperial Seal Of Approval

This article on Renewable Energy Magazine is entitled Gravitricity Technology Turns Mine Shafts into Low Cost Power Storage Systems.

This is the first paragraph.

A report by independent analysts at Imperial College London has found that Scotland-based Gravitricity’s gravity-fed energy storage system may offer a better long-term cost of energy storage than batteries or other alternatives – particularly in grid balancing and rapid frequency response services.

I am starting to believe that Gravitricity’s simple, but patented system has a future.

The Imperial report says the system has the following advantages.

  • More affordable than batteries.
  • Long life.
  • No long term degredation.

The main requirement is a shaft, which can be newly sunk or an old mine shaft.

Hopefully, reusing old mine shafts, must save costs and remove hazards from the landscape.

No-one can say the system isn’t extremely scientifically green.

I have some thoughts.

Eco-Developments

Could clever design allow a mine shaft to be both capped and turned into an energy storage system?

Perhaps then housing or other developments could be built over the top, thus converting an area unsuitable for anything into something more valuable. with built in energy storage.

More Efficient Motor-Generators

One of the keys to efficient operation of a Gravitricity system is efficient motor-generators.

These are also key to efficient regenerative braking on trains, trams and other vehicles.

So is enough research going into development of efficient motor-generators?

May 22, 2018 Posted by | World | , | 2 Comments

Report: Gravity-Based Energy Storage Could Prove Cheaper Than Batteries

The title of this post, is the same as this article on Business Green.

This is said.

Storing energy by suspending weights in disused mine shafts could be cheaper than batteries for balancing the grid, new research has found.

According to a report by analysts at Imperial College London and seen by BusinessGreen, gravity-fed energy storage systems can provide frequency response at a cost cheaper than most other storage solutions.

 

This was the conclusions of the Imperial College report.

According to the paper, gravity-fed storage providing frequency response costs $141 per kW, compared to $154 for a lithium-ion battery, $187 for lead acid batteries and $312 for flywheel.

Despite its high upfront cost, the paper argued that unlike battery-based storage systems, gravity-fed solutions have a long lifespan of more than 50 years and aren’t subject to degradation. This means they could cycle several times a day – allowing them to ‘stack revenues’ from different sources.

I always puzzle why this idea hasn’t been seriously tried before.

April 19, 2018 Posted by | World | , | Leave a comment

Huisman Weighs Into Storage

The title of this post is the same as thia article in RENews.

This is the first two paragraphs.

Edinburgh start-up Gravitricity is teaming up with Dutch lifting specialist Huisman to develop gravity-fed energy storage projects at the sites of disused mines in Scotland.

The partners plan to develop a 250kW demonstration project and test it early next year, and ultimately aim to scale up to 20MW commercial systems.

I think that this idea has a chance to be a success.

As an aside, one of my first experiences of industry was working at Enfield Rolling Mills. On one of their rolling mills, there was a ninety-three tonnes two-metre ring flywheel, which was attached to the mill. The flywheel was spun to 3000 rpm, before the copper wirebar was passed through the mill. You could see the flywheel slow, as it passed it’s energy to the mill, as it turned the wirebar into a thinner strand of copper, so that it could be drawn into electrical cable.

I think, that flywheel had an energy storage of over a MwH. Shimatovitch, the Chief Engineer reckoned that if had come of its mountings at full speed, it would have gone a mile before the houses stopped it.

March 22, 2018 Posted by | World | , , | 2 Comments

Would The Gravitricity Concept Work At Sea?

The North Sea and other similar places have lots of oil oil and gas platforms, that are coming to the end of their lives.

Many are being dismantled and scrapped.

But could some be used to store energy by replacing the refitting the deck with a Gravitricity energy  storage system. The massive weight would be hauled up and down from the sea bed.

It would be fed generated electricity from nearby offshore wind turbines and would store or feed the electricity to the shore as required.

Remember that some of these oil platforms have been built to support decks weighing thousands of tonnes, so would be strong enough to support the massive weight needed for a Gravitricity system.

If the height was say 500 metres and the weight was 10,000 tonnes, this would equate to just under 14 mWh.

 

February 10, 2018 Posted by | World | , | 2 Comments

Gravitricity Sets Sights On South Africa To Test Green Energy Tech

The title of this post, is the same as that of this article on ESI Africa, which describes itself as Africa’s Power Journal.

This is the first two paragraphs.

Disused mine shafts in South Africa have been identified as an ideal location to test UK-based energy start-up Gravitricity’s green energy technology.

The company announced plans to transform disused mine shafts into hi-tech green energy generation facilities through a system that uses gravity and massive weights.

This is surely a classic fit, as Africa has plenty of sun and some of the mine shafts in South Africa, like the TauTona mine are getting towards two miles deep.

A weight of 1,000 tonnes in a two mile deep shaft would store nearly nine MWh. By comparison, Dinorwig Power Station or Electric Mountain, has a capacity of 500 MWh.

But Electric Mountain was built in the 1970s, cost £425 million and took ten years to construct.

 

February 10, 2018 Posted by | World | , , , | Leave a comment

Funding Gives Weight To Idea For Storing Electricity

The title of this post, is the same as that of an article on Page 45 of today’s copy of The Times.

It talks of a company called Gravitricity, which has used the same principle as every weight-operated clock to store energy and especially energy generaed from intermittent sources like wind and solar power.

The company has just secured a £650,000 grant from Innovate UK.

In Solar Power Could Make Up “Significant Share” Of Railway’s Energy Demand, I looked at how solar farms and batteries could be used to power third-rail railway electrification.

Because of energy losses, third-rail electrification needs to be fed with power every three miles or so. This gives a problem, as connection of all these feeder points to the National Grid can be an expensive business.

A series of solar farms, wind turbines and batteries, controlled  by an intelligent control system, is an alternative way of providing the power.

In an article in the October 2017 Edition of Modern Railways, which is entitled Celling England By The Pound, Ian Walmsley says this in relation to trains running on the Uckfield Branch.

A modern EMU needs between 3 and 5 kWh per vehicle mile for this sort of service.

If I assume that trains are five cars and will be efficient enough to need only 3 kWh per vehicle mile, then to power a train along a ten mile section of track will take 150 kWh.

As the control system, only powers the track, when a train needs it, the whole system can be very efficient.

So why will Gravitricity battery ideas be ideal in this application?

Appropriate Size

By choosing the right weight and depth for the Gravitricity battery , appropriate energy storage can be provided at different points on a line.

Some parts of a journey, like accelerating away from stations will need more electricity than others, where trains are cruising along level ground.

Supposing my five-car example train is travelling at 60 mph, then to cover ten miles will take 10 minutes, with 15 kW being supplied in every minute.

If the train weighs 200 tonnes, then accelerating the train to 60 mph will need about 20 kWh.

I’m sure that a Gravitricity battery could handle this.

I would suspect that batteries of the order of 100 kWh would store enough power for the average third-rail electrified line.

A proper dynamic simulation would need to be done. I could have done this calculation in the 1960s, but I don’t have the software now!

Response Time

For safety and energy-efficiency reasons, you don’t want lines to be switched on, when there is no train present.

I suspect that if there is energy in the battery, response would be fast enough.

Energy Efficiency

The system should have a high efficiency.

How Big Would A 100 kWh Gravitricity Battery Be?

A quick calculation shows the weight would be 400 tonnes and the depth would be 100 metres.

Installing the batteries

Each battery will need a 100 metre deep hole of an appropriate diameter.

This sequence of operations would be performed.

  • A rail-mounted drilling rig would drill the hole.
  • The heavy weight of the battery would arrive by train and would be lifted into position using a rail-mounted crane.

As the equipment will generally be heavy, doing all operations from the railway will be a great help.

 

 

 

February 9, 2018 Posted by | Travel | , , , | 1 Comment