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

Existing EVs Could Steer Energy To 300,000 Homes

The title of this post, is the same as this article on the Utility Week web site.

This is the opening two paragraphs.

Existing electric vehicles (EVs) in the UK could contribute more than 114MW to the National Grid, enough to power over 300,000 homes.

Research commissioned by Ovo Energy suggests the figure could be achieved based on the current 19,000 Nissan Leaf EVs registered in the UK using new vehicle-to-grid (V2G) chargers.

The article goes on to discuss this in detail.

So what is vehicle-to-grid?

Wikipedia has this summary.

Vehicle-to-grid (V2G) describes a system in which plug-in electric vehicles, such as electric cars (BEV), plug-in hybrids (PHEV) or hydrogen Fuel Cell Electric Vehicles (FCEV), communicate with the power grid to sell demand response services by either returning electricity to the grid or by throttling their charging rate.

Vehicle-to-grid can be used with gridable vehicles, that is, plug-in electric vehicles (BEV and PHEV), with grid capacity. Since at any given time 95 percent of cars are parked, the batteries in electric vehicles could be used to let electricity flow from the car to the electric distribution network and back. This represents an estimated value to the utilities of up to $4,000 per year per car.

If you are thinking about buying an electric car or van, read the article and other sources. Wikipedia seems a good start.

At its simplest, it would appear that if you buy an electric vehicle, it would be prudent to fit a V2G charger in your garage or parking space.

I would expect, that the charging system is sophisticated, so that if you want to use the car, there is sufficient charge and the power hasn’t been sold back to the grid.

It will be very interesting to see how this technology develops.

March 17, 2018 Posted by | Travel | , , | Leave a comment

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

The Future Of Diesel Trains

Many feel that diesel trains have no future in the modern world, because of all those carbon and particulate emissions.

However, this article in Rail Technology News, which is entitled ScotRail To Trial Hydraulic Tech To Cut Of Carbon Emissions.

This is the first paragraph.

A new hydraulic pump could reduce Scotland’s carbon emissions by 4,000 tonnes of carbon dioxide per year.

This sounds impressive, but how is it done?

Many modern diesel muiltiple units, like the Class 170 trains, used in the ScotRail trial have hydraulic transmissions, where a pump fitted to the engine creates hydraulic power, which then drives a hydraulic motor to power the train.

But modern trains also need to have electricity in each car for lighting, air-conditioning and other services.

So typically, a hydraulic unit in each car is used to generate the electricity required.

It is this hydraulic unit, that has been replaced by a much more efficient digitally-controlled hydraulic unit.

That sort of hydraulic unit has one Scottish company’s stamp all over it; Artemis Intelligent Power, which started as a spin-off from Edinburgh University.

Artemis Intelligent Power has a page about Rail applications on their web-site.

This is the introductory paragraphs to their work.

Whilst electrification has enabled the de-carbonisation of much of the UK’s rail sector, the high capital costs in electrifying new lines means that much of Britain (and the world’s) railways will continue to rely on diesel.

In 2010, Artemis completed a study with First ScotRail which showed that between 64 and 73 percent of a train’s energy is lost through braking and transmission.

In response to this, Artemis began a number of initiatives to demonstrate the significant benefits which digital hydraulics can bring to diesel powered rail vehicles.

Two projects are detailed.

The first is the fitting of a more efficient hydraulic unit, that is described in the Rail Technology Magazine article.

Under a heading of Faster Acceleration, Reduced Consumption, there is a technical drawing with a caption of The Artemis Railcar.

This is said.

We are also working with JCB and Chiltern Railways on a project funded by the RSSB to reduce fuel consumption and improve engine performance by combining highly efficient hydraulic transmission with on board energy storage in the form of hydraulic accumulators, which store energy during braking for reuse during acceleration.

Note.

  1. The use of hydraulic accumulators to provide regenerative braking.
  2. The involvement of JCB, whose construction equipment features a lot of hydraulics.
  3. The involvement of Chiltern Railways, who like their parent company, Deutsche Bahn, have a lot of diesel-hydraulic multiple units and locomotives.

The article goes on to detail, how a test railcar will be running before the end of 2017.

This technology could have tremendous potential in the UK.

The Benefit Of Regenerative Braking

In the Wikipedia entry for Regenerative Brake, this is said.

Savings of 17%, and less wear on friction braking components, are claimed for Virgin Trains Pendolinos. The Delhi Metro reduced the amount of carbon dioxide (CO2) released into the atmosphere by around 90,000 tons by regenerating 112,500 megawatt hours of electricity through the use of regenerative braking systems between 2004 and 2007.

The entry also says that some London Underground trains save twenty percent.

It would be a large benefit to the train operating companies, if they could just have a similar saving on the cost of diesel fuel.

Could Existing Trains Be Converted?

In England, Wales and Scotland,currently there are around two hundred modern Turbostar diesel multiple units. of which thirty are used by Chiltern Railways.

Whether these can be converted, depends on the engineers and the result of the current trial, but the economic benefits of a successful conversion route could be very beneficial.

Conclusion

This is technology to watch!

 

 

December 30, 2017 Posted by | Travel | , , | 1 Comment

Hybrid Trains Proposed To Ease HS1 Capacity Issues

The title of this post is the same as an article in Issue 840 of Rail Magazine.

This is the first paragraph.

Battery-powered hybrid trains could be running on High Speed 1, offering a solution to capacity problems and giving the Marshlink route a direct connection to London.

Hitachi Rail Europe CEO Jack Commandeur is quoted as saying.

We see benefit for a battery hybrid train, that is being developed in Japan, so that is an option for the electrification problem.

I found this article on the Hitachi web site, which is entitled Energy-Saving Hybrid Propulsion System Using Storage–Battery Technology.

It is certainly an article worth reading.

This is an extract.

Hitachi has developed this hybrid propulsion system jointly with East Japan Railway Company (JR-East) for the application to next-generation diesel cars. Hitachi and JR-East have carried out the performance trials of the experimental vehicles with this hybrid propulsion system, which is known as NE@train.
Based on the successful results of this performance trial, Ki-Ha E200 type vehicle entered into the world’s first commercial operation of a train installed with the hybrid propulsion system in July 2007.

The trains are running on the Koumi Line in Japan. This is Wikipedia’s description of the line.

Some of the stations along the Koumi Line are among the highest in Japan, with Nobeyama Station reaching 1,345 meters above sea level. Because of the frequent stops and winding route the full 78.9 kilometre journey often takes as long as two and a half hours to traverse, however the journey is well known for its beautiful scenery.

The engineers, who chose this line for a trial of battery trains had obviously heard Barnes Wallis‘s quote.

There is no greater thrill in life than proving something is impossible and then showing how it can be done.

But then all good engineers love a challenge.

In some ways the attitude of the Japanese engineers is mirrored by those at Porterbrook and Northern, who decided that the Class 769 train, should be able to handle Northern’s stiffest line, which is the Buxton Line. But Buxton is nowhere near 1,345 metres above sea level.

The KiHa E200 train used on the Koumi Line are described like this in Wikipedia.

The KiHa E200 is a single-car hybrid diesel multiple unit (DMU) train type operated by East Japan Railway Company (JR East) on the Koumi Line in Japan. Three cars were delivered in April 2007, entering revenue service from 31 July 2007.

Note that the railway company involved is JR East, who have recently been involved in bidding for rail franchises in the UK and are often paired with Abellio.

The Wikipedia entry for the train has a section called Hybrid Operation Cycle. This is said.

On starting from standstill, energy stored in lithium-ion batteries is used to drive the motors, with the engine cut out. The engine then cuts in for further acceleration and running on gradients. When running down gradients, the motor acts as a generator, recharging the batteries. The engine is also used for braking.

I think that Hitachi can probably feel confident that they can build a train, that can handle the following.

  • High Speed One on 25 KVAC overhead electrification.
  • Ore to Hastings on 750 VDC third-rail electrification.
  • The Marshlink Line on stored energy in lithium-ion batteries.

The Marshlink Line has a big advantage as a trial line for battery trains.

Most proposals say that services will call at Rye, which is conveniently around halfway along the part of the route without electrification.

I believe that it would be possible to put third-rail electrification in Rye station, that could be used to charge the batteries, when the train is in the station.

The power would only be switched on, when a train is stopped in the station, which should deal with any third-rail safety problems.

Effectively, the battery-powered leg would be split into two shorter ones.

 

November 23, 2017 Posted by | Travel | , , , , , | Leave a comment

How Much Energy Does A Crossrail Class 345 Train Use?

I will start with the Crossrail Rolling Stock Technical Fact Sheet, which dates from 2012.

The Class 345 trains were built to this specification.

This is said about the power required.

Energy efficiency of 24 KWh per train kilometre (equivalent of 55g CO2 per passenger kilometre)

So what does this mean now that trains are running and trains will have been designed and probably accepted to this specification.

Assuming, that trains will be nine-car when completed, 24 KWh per train per kiometre translates into 2.67 KWh per car per kiometre or 3.29 KWh per car per mile.

Ian Walmsley’s Train Energy Usage Figure

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.

My calculated value is in line with this figure, as the Uckfield Branch is not that different to some of the Crossrail branches.

What Is The Kinetic Energy Of A Crossrail Train?

I ask this question to show the energy values involved.

If I take a nine-car Class 345 train, this has a mass of less than 350 tonnes and a maximum speed of 145 kph.

1500 passengers at 80 kg each works out at another 120 tonnes.

So for this crude estimate I’ll use 450 tonnes for the mass of a loaded train.

This gives the train an energy of 365 megajoules or 101 KWh.

This amount of energy is only a couple of KWh larger than the largest battery size of a Tessla Model S car.

It leads to the conclusion, that batteries could be large enough to store the regenerative energy generated by the train, when it stops.

How Far Could A Crossrail Train Run On Batteries?

If the batteries were sized for the regenerative braking, then a battery of 100 KWh would probably be sufficient in most circumstances.

Using Crossrail’s figure of 24 KWh per train per kiometres, gives a convenient range of four kiometres, which is probably in excess of the largest distance between stations.

But Crossrail trains are effectively two half-trains with two pantographs.

So perhaps they will be fitted with two batteries!

The battery capacity would be arranged to give the desired amount of emergency power.

Conclusion

There’s a lot more to learn about these Crossrail trains.

 

November 16, 2017 Posted by | Travel | , , | 1 Comment