Pumped hydro looks good at 40

The Ludington Pumped Storage Plant on the Lake Michigan shoreline.

The Ludington Pumped Storage Plant on the Lake Michigan shoreline. Photo credit: Consumers Energy

We’ve already seen that, despite massive initial capital costs, the amount of energy needed to build a pumped hydro plant compared with its lifetime storage capacity makes it the most efficient energy storage investment in the game. So it’s great to see a project showing that even though you’ve been around for four decades, you still have plenty to offer the grid and its customers.
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Doughnuts: just the thing for storage?

Depending on your point of view the plan announced by Belgium earlier this year is either pure James Bond, or straight from The Simpsons. The Bond take: the Belgian government is going to create a private island to help harvest power from the sea. Simpsons: the Belgians are building a giant doughnut to do away with nuclear power plants like Springfield.

Whatever your perspective, though, there is no doubt the Belgian scheme has the potential to change the script for marine renewable energy storage. In essence the idea is simply a new solution for that age-old conundrum of how to add storage to intermittent renewable energy sources such as wind, solar or wave power so they can be used for base-load power generation. But what a solution!

According to Reuters, the concept announced by Belgian North Sea minister Johan Vande Lanotte at a Zeebrugge port presentation will involve building a doughnut-shaped island out of sand three kilometres off the coastal village of Wenduine.

The hole in the middle will be filled with water that will be pumped out whenever there is excess power coming from the country’s offshore wind farms, which are ultimately planned to be able to deliver up to 2,300MW.

In times of need, meanwhile, gates in the walls of the doughnut/island will be opened up and the water flowing into the hole in the middle will be used to drive turbines, delivering hydro power that can be sent to shore.

The government reckons it will take at least five years to build but will help the country shift away from its reliance on nuclear power, which in 2011 accounted for about 57% of the energy consumed. Belgium currently has seven nuclear reactors in two power plants, at Doel and Tihange, generating a total of 5,761MW.

Two of the reactors were shut down last year after the operator, GDF Suez subsidiary Electrabel, found flaws in their reactor casings. Two more are due to be retired in 2015, with the rest following suit by around 2025. “This is a great solution,” a ministerial spokeswoman said in the Reuters report.

“We have a lot of energy from windmills and sometimes it just gets lost because there isn’t enough demand for the electricity.”

She is absolutely right. Although novel in terms of its scale and location, this is essentially a pumped hydro project. And pumped hydro goes with wind energy like Charlie Chaplin with a walking stick. The technique is already used extensively by Iberdrola of Spain to maximise the value of its myriad wind energy farms.

Meanwhile the Spanish island of El Hierro is on track to become 100% self-sufficient using wind energy, thanks to the Gorona del Viento project that uses a double-dam setup powered by onshore Enercon turbines.

On a wider scale, the immense hydro resources across Scandinavia could potentially play an important role in helping to store and redistribute energy from offshore wind farms in Germany and the UK. What does the Belgian proposal add to this picture, in terms of its significance for the marine renewable energy storage market? Three things, at least.

The first is that it would vindicate the idea that intermittent renewable energy, including marine generation from wind, wave and even floating solar, can be more than a match for existing base-load sources if combined with appropriate storage.

After all, let us not forget that the Belgians are not planning to replace gas peakers here, but nuclear power plants, arguably one of the steadiest pillars of base-load power provision.

The second point of note is any power generation scheme that involves shifting water in and out of a closed environment within a marine context would seem to be just crying out for integration with other ocean-based energy sources.

Belgium is clearly intending for the island storage facility to be used with wind power, for example, but could additional efficiencies be gained through clever engineering to trap tidal or even wave energy, too?

Finally, a point that will not escape the attention of policy makers elsewhere is that this is a project that will allow Belgium to produce its own, clean base-load power indefinitely, based on offshore wind. In other words, integrating wind power into its grid will not be a problem. It will not require a massive juggling act involving smart grids or electric vehicle batteries.

Nor will it involve costly and tricky grid connections to neighbours. Best of all, it will probably create thousands of jobs during the construction phase, and hundreds for ongoing operations, equivalent to the building of a new nuclear power plant but without the discomfort of radioactive waste or pressure groups.

Of course, the project, which is still awaiting a green light, is presumably not without its challenges. Building an entire island is no mean feat. One wonders where all that sand is going to come from, for a start. The Belgian government has also already recognised that Elia, the national grid provider, will have to strengthen its connections to the region.

Cost could be an issue, too; a government estimate of ‘about the same as a wind farm’ is difficult to evaluate without further details. Nevertheless, what is certain is that developments off the Belgian coast could be attracting a lot of attention in the next half-decade. Let’s just hope this doughnut doesn’t leave a bad aftertaste.

This article was previously published in Marine Renewable Energy.

Another take on undersea batteries

Little more than a fortnight after a Massachusetts Institute of Technology proposal to store wind energy in a form of underwater pumped hydro comes news of a Norwegian company with a similar idea, according to Gigaom. The system proposed by Subhydro would consist of concrete tanks sited on the seabed at depths of between 400 and 800m.

‘Discharging’ the battery would consist of opening a port to allow seawater to rush into these empty tanks at many times atmospheric pressure, driving a turbine and generating electricity. Recharging is simply a matter of reversing the process, using cheaper non-peak or surplus energy to pump the water out of the containers. The company is claiming an 80% efficiency for the system, which they say is comparable to efficiencies achieved at conventional plants.

New ball game for sea power storage

It’s only a proposal. But it’s an idea that could make offshore wind a lot more dependable and cost-effective, says the Massachusetts Institute of Technology (MIT): storing surplus energy from wind turbines in a concrete sphere under water. The principle is straightforward.

During periods when there is more wind energy than immediate demand, the additional power would be used to pump seawater out of a hollow, submarine sphere. Later, when power is needed, water would be allowed to flow back into the sphere through a turbine attached to a generator and the resulting electricity sent back to shore. MIT has calculated that a 25m sphere in 400m-deep water could store up to 6MWh of power.

Multiply that figure up and 1,000 turbines with this form of pumped hydro energy storage could rival a nuclear power station, for a matter of hours at least. The big drawback is a minimum 200m depth of water required to make the scheme feasible, especially as off-shore wind, which currently only enjoys popularity in Europe, is currently sited in waters shallower than 30m.

But the ability to provide despatchable energy without the need for large-scale batteries on or offshore is clearly a huge plus for the idea.

Could Nordics be Europe’s battery pack?

This article was previously published in Marine Renewable Energy.
It is a bit like buses: you wait ages for a North Atlantic power interconnector and then two come along at once. At the moment it is fair to say there is a lot of interest in getting an energy link set up between Norway and the UK. First up on the road to better energy connections across the North Sea is a project called HVDC Norway-UK, backed in equal parts by the grid operators of the two countries concerned: Norway’s Statnett and the National Grid in the UK.

This scheme, which has been under discussion since 2003, would see the development of a high-voltage direct current (HVDC) link with a 1,400MW capacity. The Norwegians have selected Suldal, in the south west of the country, as their landing point. Meanwhile the UK terminal has moved somewhat since the project’s inception.

Originally it was due to be in Northern Ireland: Easington in County Durham, to be precise. The location has since moved to Blyth, Northeast England, involving a route that would require around 710 km of cable. Statnett and National Grid figure the project would cost GBP£1.3 billion and could be operational in 2020. But since 2011 it has had a competitor, in the form of a scheme called NorthConnect.

Again featuring a 1,400MW HVDC link, NorthConnect is very much a Nordic energy sector affair, with a list of backers that reads like a who’s who of the Scandinavian power industry. It includes the Norwegian electricity firms Agder Energi, E-CO and Lyse, and the Swedish energy giant Vattenfall. Sources close to the project have confirmed the partners do not all have equal shares in it.

The proposed UK landing point for NorthConnect is in Scotland, at Peterhead Aberdeenshire, rather than England. And the project is currently due to kick off around 2019 or 2020, with a £1.75 billion price tag. It is unlikely that both projects will go ahead at the same time, and NorthConnect in particular faces potential regulatory challenges in Norway.

But what is clear is that there is an increasingly good chance of Norway having an energy connection to the UK by around the beginning of the next decade.
And that is potentially very significant news for renewable energy on both sides of the North Sea. The UK in particular is rushing headlong towards a situation where it may soon be taking on board very large amounts of intermittent, ocean-based power.

Yet it currently lacks any significant energy storage capacity with which to hang on to any excess. The easiest and most commonly used way to store large amounts of surplus renewable power is to use it to pump water into dams and retrieve it later in the form of hydro energy.

Pumped hydro currently accounts for about 90% of all energy storage in the world but in the UK there is hardly enough to store the surfeit of power likely to come off the North Sea on a windy night in a few years’ time. With a NorthConnect or a HVDC Norway-UK in place, however, the UK would have the option of shipping any energy it could not use over to Scandinavia.

Of course, it is unlikely that Norway would have any more need for large amounts of energy on a windy night than the UK might. But sending power to Scandinavia raises two interesting prospects. The first is that it could then be forwarded on to other parts of the continent, such as Germany, which may indeed have increased power requirements. The Nordic countries already have their sights set on improving their energy export capabilities.

In addition to the two potential links to the UK, Norway is planning to build a 1,400MW interconnector with Germany by 2018, according to reports. And a second, related option is that excess renewable power from the UK, or even Germany for that matter, gets bought up cheaply by Norway and is stored in Scandinavian pumped hydro facilities, to be re-sold later on. Unlike the UK or Germany, the Nordic countries have ample pumped hydro potential.

They already get more than half their electricity from hydro, which is generally credited with allowing them to enjoy lower power prices than gas-guzzling counterparts elsewhere in Europe. Ilesh Patel, a partner at the energy consultancy firm Baringa, says the creation of power links with Norway could in theory be seen as a way of giving European marine renewable energy generators a battery pack.

However, he adds, the industry needs to be aware that this form of storage will only be an option when the financial incentives are properly aligned on either side of the interconnector. “Is an interconnector to Norway an additional form of storage? The answer is yes,” he says. “Will that work all the time? It depends on the economies of arbitrage. You can only store power in Norway’s reservoirs when there’s an economic profit to be had by doing so.

“You might make that bet if you thought you might need that power back next week, but it carries a risk with it.”

Clearly, then, Scandinavia’s pumped hydro potential will not work for everyone all of the time. But until Europe gets a proper handle on the increasingly serious issue of energy storage, as far as renewable energy suppliers are concerned the pumped hydro option is probably going to be a whole lot better than nothing.

Giant hydro project announced

A massive pumped hydro energy storage project proposed for lakes around the Niagara Falls would store a staggering 10GW, making it the planet’s largest pumped hydro site with four times the capacity of China’s Huizhou Pumped Storage Power Station, the current world number one.

Currently just a gleam in the eye of cleantech entrepreneur Roger Faulkner, the proposed Isthmus of Niagara project has the huge advantage that it would not need any land to be flooded as it relies on the 99.4m average height difference between Lakes Ontario and Eerie. The idea would be to connect these two huge bodies of water with a cana, rather than building two enormous artificial reservoirs.

Faulkner has factored in a 30cm change in the water level of the lakes between charging and discharging, which he insists is less than the lakes’ natural seasonal variation. He makes the case for his proposal having a lower environmental impact than traditional pumped hydro energy storage projects but acknowledges that it would be an enormous engineering project, needing a vast amount of political will in order to see it through to completion.

Report puts pumped hydro ahead

Around 12.1% of US energy comes from renewable sources, but its grid only has the ability to store a pitiful 1%. As renewables such as wind and solar increasingly enter the mix, the need for the more storage will certainly need to grow considerably, too. So what technologies would be most energy efficient, if a whopping 80% of the country’s requirements were to be from renewables? Stanford University researchers Charles Barnhart and Sally Benson decided to find out.

They made a comparison of pumped hydroelectric storage, compressed air energy storage, and lead-acid, lithium-ion, sodium-sulphur, vanadium-redox and zinc-bromine batteries. The criteria in each case was looking at how much energy it would take to produce the technology, compared with the amount of energy it could store during a 30-year lifespan. The greater the ratio of energy stored to energy expended, the better the option the technology would be, over the longer term.

The report found that pumped hydro gave by far the best return in terms of energy stored to energy expended, with a ratio of 210. The best lithium-ion batteries, by comparison, only managed a score of 10, while the worst batteries, lead-acid, only score two. The reason for such small ratios is the relatively small number of recharge cycles. Lithium-ion batteries can handle at most around 6,000 cycles and lead-acid batteries only 700, compared to more than 25,000 cycles for a pumped hydro project.

Pumped hydro will benefit Ontario’s grid

Toronto-based Northland Power plans to construct a USD$700m pumped hydroelectric project using the enormous hole and mountain of tailings left by an abandoned open-pit iron ore mine. Water would be pumped up from the old mine working up into a newly constructed reservoir during periods of  cheap, night-time electricity.

When demand and prices go up, the company would release the water for a 258-metre plunge to a powerhouse and generate 400MW of power, creating a waterfall five times the height of Niagara Falls, though with a fraction of the volume. The facility will also be used to store excess wind power, which in Ontario is forecast to increase from today’s 1.7GW to 7.8GW by 2018.