The Regenesys energy storage system – one of the UK’s most promising fledgling technologies – is in limbo after its new German owners pulled the plug when it was on the very brink of commercialisation.

The move is a severe blow to the UK’s position in what could prove a significant emerging area of power technology. It also raises wider questions over the commercial viability of energy storage, seen by many as a key component of future power networks that will make greater use of renewable energy sources.

With the first full-scale plant poised to go on-line, utilities giant RWE made the shock announcement last month that investment in Regenesys would cease immediately. Last year RWE bought Innogy, the energy group that spent a decade developing Regenesys. If all had gone to plan, some time during the next few months Innogy would have been flicking the on-switch of a genuine UK technology first.

Billed as the world’s biggest battery, Regenesys was designed to act as an ‘electricity warehouse’, allowing power to be stored when usage is low and released into the network at times of peak demand. It also offered a potential bulwark against unexpected failures of the national power network by piping emergency electricity to local users while supplies are restored.

The regenerative cell technology was, by common consent, a breakthrough in energy research (see sidebar, below). The first Regenesys facility at Little Barford, Cambridgeshire, would have been at least equal to – and in the view of many ahead of – any comparable technology in the world. In fact, it was held to be such an exciting prospect that Regenesys had already been exported to the US even before storing a megawatt of power here (see sidebar, below). Like many on this side of the Atlantic, the Americans were ‘surprised and disappointed’ by RWE’s pulling the plug – and also want to recover some of the $30m (£16m) they spent on the project.

RWE said its decision arose from a ‘shift in strategic focus’ that will see it concentrate on its core power generation and sales operations. Energy storage technology, and specifically Regenesys, was deemed outside this remit, along with some other peripheral activities such as telecoms services. ‘Unfortunately prioritising means having to decide not to go forward with some things, and in this case Regenesys had to be one of those,’ said an RWE Innogy spokesman.

The firm is believed to have entered into talks with several potential buyers without success, and confirmed that it remains open to ‘any appropriate offers’ for the intellectual property.

Unless and until a buyer is found, ‘so near yet so far’ will be the overwhelming emotion of those involved in Regenesys, which has been under development for 15 years at a total cost approaching £100m. The modules for the first 2.4MW of the 12MW Little Barford plant were installed and being commissioned when RWE halted it.Energy consultant Anthony Price has worked on the development of Regenesys from its earliest days in the laboratories of National Power. Though he was reluctant to comment specifically on RWE’s decision, his disappointment at the project’s sudden demise so near to fruition was apparent.

Price said that, whether filled by Regenesys or another technology, a gap in the market exists at the megawatt storage range in which the UK initiative was designed to operate. This is bigger than the limited storage capability of conventional batteries but below that of large-scale pumped-hydro or compressed-air storage projects, for which geographical sites are limited.

A system operating in the 5MW to 30MW band would, according to Price, fit perfectly with the drive towards distributed energy – smaller energy networks that combine different generation and management technologies to manage local power supplies more efficiently. ‘With the rise of distributed energy you are opening up a whole new market sector,’ he said. ‘You could start integrating energy storage with fuel cells, wind power and possibly micro-turbines.’

Regenesys was, in many ways, ideally suited to the purpose. Its flexible, modular approach meant it could be adapted to the particular needs of a network and used on a small scale if necessary. It could react efficiently, switching swiftly from the absorption of energy to pushing it back into the network. Crucially, it also offered a possible solution to the intermittent and unpredictable behaviour of clean energy technologies such as wind power.

According to Price, even competitive foreign technologies were rooting for it. ‘Every energy storage manufacturer wanted Regenesys to succeed,’ he said. ‘That would have meant this new market could be opened up for the first time.’

As things stand, that task will fall to another system. ‘The UK ought to have a presence in energy technologies that have a significant potential worldwide market,’ said Price.

Regenesys had plenty of fans beyond the energy industry, and until the shutdown Innogy was working with research partners around the UK to perfect the system. Confidence in the technology was high, and those working on it were surprised and dismayed by the project’s sudden end.

Sheffield University had a research centre called Suretec devoted to working on the Regenesys fuel cell, and particularly the flow and containment of electrolytes within it. Dr Steve Joseph of Sheffield’s department of mechanical engineering, said Regenesys was, as far as he knew, the most advanced project of its type. ‘There was nothing I could see that would prevent it from becoming viable. It was at the stage of being made into a working plant,’ he said.

Although Sheffield has not lost out financially, its team has no immediate outlet for the expertise it developed during its work with Regenesys. ‘We are looking at alternatives to see if there’s anyone going down the same road,’ said Joseph. ‘It’s exactly the type of technology you want for your wind-mills. It’s the sort of generic technology that would merit global programmes.’

Like everyone involved with Regenesys, Joseph is waiting to see if anyone else is prepared to buy the technology from RWE and continue the research.

Such technological barriers as remained were being overcome. ‘That being said, no technical problem can ever be resolved at a price that satisfies the commercial people,’ said Joseph.

It seems clear that the ‘commercial people’ in RWE saw something in Regenesys that to their minds didn’t add up. For all its talk about strategic focus, it seems unlikely that the company would have abandoned the project at such an advanced stage, with much of the development capital long since spent, if it thought there was a chance of it becoming a major asset.

Regenesys appears to have suffered a classic squeeze between short-term commercial imperatives and longer-term, more imponderable benefits. More specifically, it may be a victim of the hugely complex nature of the energy market and its precarious balancing act between the economic interests of producers, distributors and consumers.

David Milborrow, an independent energy analyst, said: ‘It was always going to be a challenge to get the cost down to the level at which it would pay for itself.’That task is made even harder, said Milborrow, by the electricity industry’s razor-tight margins. ‘For a storage facility to succeed commercially, there has to be a decent differential between the price at which you can buy and sell electricity.’

Despite the challenging market conditions, Milborrow was a ‘big fan’ of Regenesys’s technology. ‘With my engineer’s hat on, I was very impressed by it. It had a lot of potential and it would be a shame if once again a UK technology founders and others come to the fore.’

The national pride of the UK energy sector may be bruised by the abrupt termination of Regenesys, but does it have wider implications for the future of energy storage as a whole?

The UK initiative was one of a number of projects across a range of technologies seeking to give power networks a holding option between generation and distribut-ion. These include the battery system being built in Alaska by the Golden Valley Electricity Association in conjunction with engineering giant ABB (see sidebar, below). Other contenders include a Japanese sodium sulphur battery and a US technology based on zinc bromide.

Beyond batteries, research is ongoing into the use of superconducting magnets as an energy storage technology. These systems hold energy in the magnetic field created by cryogenically cooled superconducting material.

Flywheel storage is a well-established principle, and there is growing interest in the idea of converting energy into hydrogen, storing it and then burning it to re-release the energy when needed.

There is no guarantee that any of these, if applied on a large scale, will not run up against the same type of commercial brick wall that seems to have blocked Regenesys. However, if a set of cost-effective technologies can be developed, their real benefit is likely to come in two or three decades rather than a couple of years. By that stage the UK will hopefully have made some tough choices about how its national energy needs should be met. The government, apparently committed to the winding-down of nuclear generation, is currently talking up the role wind farms and other renewables will play.

Dr. Keith Tovey, energy science director at the University of East Anglia’s Low Carbon Innovation Centre, said that in the long term if the UK and other countries want to generate more power from renewable sources the question of storage will have to be addressed. ‘Once we get to 15 per cent of renewables it could become an issue,’ he said. ‘All these technologies will need to be explored. There is no doubt that 40 years down the road we will need extra storage.’

There lies the problem. Forty years is an unimaginably long time for governments and eagle-eyed accountants alike. Regenesys may end up enjoying its day in the sun when few that were present at its inception are around to witness it.

Sidebar: Giant ‘warehouse’ for electricity

Regenesys harnesses the power of chemistry to create a giant ‘warehouse’ for electricity. Its regenerative fuel cell technology converts electrical power into chemical potential energy and back again via a reversible electrochemical reaction.Each Regenesys cell consists of two liquid electrolyte solutions made up of sodium bromide and sodium polysulphide salts.

A single cell has a charged potential of just 1.5V, about the same as a small battery. But the beauty of Regenesys is the ability to connect many cells via shared electrodes, creating a module.

The modules are then operated in parallel to provide the desired power. The system is designed to store 5MW-500MW over periods ranging from a few seconds to 12 hours.

Regenesys was hailed as nothing short of revolutionary by Innogy, then part of National Power, when it unveiled the technology in 2000 after spending much of the 1990s developing it.

Innogy was so convinced of its commercial potential that it immediately announced plans to float Regenesys as a separate venture, and there was even speculation that the technology could end up being worth more than the company’s power station business.

Sidebar: Ensuring power supplies in -50 degree C winters

One of the world’s most ambitious energy storage projects was launched to help ensure continuous power supplies to Alaska, one of the most inhospitable winter climates on Earth.

The battery energy storage system (Bess) built for Alaska’s Golden Valley Electric Association is the world’s most powerful single storage battery (Regenesys was due to become the largest in terms of storage capacity).

Costing $35m (£18.7m), the 1,500-ton system was developed for the utility company by Swiss engineering giant ABB. Bess was built to protect 90,000 residents in the Fairbanks region from the effect of power cuts. Temperatures in the Alaskan winter can fall to -50 degrees C, and homes left unheated will begin to suffer frozen pipes in just a few hours. Bess has already prevented four outages since coming into operation in November 2003.

It is designed to provide 27MW of back-up for 15 minutes. The system’s nickel cadmium batteries are connected to a DC/AC converter.

With a life of 20-30 years the batteries consist of almost 14,000 liquid electrolyte-filled nickel cadmium cells. The converter changes the batteries’ DC power into AC for use by the electricity grid’s transmission system. The batteries will also provide continuous voltage support during normal operation.

Sidebar: Regenesys in the US

US power giant Tennessee Valley Authority has more reason than most to lament the apparent demise of Regenesys. Knoxville-based TVA was a vocal advocate of the merits of the technology, and put its money where its mouth is to the tune of $30m (£16m). The second Regenesys plant in the world, coming on-line soon after Little Barford, would have been TVA’s facility near the Columbus Air Force Base in Mississippi.

The plant was intended to provide a reliable power supply to the USAF and the surrounding area. It would also have created a showcase for Regenesys in the world’s biggest economy, where power is a major issue following some high-profile supply problems over recent years.

Dr. Joe Hoagland, TVA’s senior manager for clean and advanced energy, summed up the company’s reaction to RWE’s decision as ‘surprised and disappointed. Our Regenesys plant was 85 per cent complete.’ Unfortunately, Regenesys had yet to deliver the vital fuel cell modules needed to complete the project. ‘Without those modules we have no way to finish the plant,’ said Hoagland.

With Little Barford expected to be up and running any time, Hoagland and his team expected to be packing their bags for Cambridgeshire to gain vital first-hand experience of a working Regenesys facility. Instead, they are trying to pick up the pieces and are negotiating the return of at least part of their $30m investment.

Hoagland remains convinced that the UK technology could have done a fine job. ‘I believe Regenesys was scientifically sound. There were some engineering issues, as there always are with a new system, but they were being sorted out.’

However, Hoagland conceded that there were cost issues around the technology. ‘It would have needed to get less expensive, but these were the type of issues we could have looked at when one or two plants were up and running.’ TVA would not buy Regenesys, said Hoagland, ‘but I hope somebody could pick it up’.

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