Regensys Large Scale Utility Energy Storage

National Power (U.K.), has announced a new electricity storage technology – called Regenesys – in which a flowing electrolyte is charged and then and stored in tanks for later use. It has a high speed of response, supplies real and reactive power and is therefore suited to many different applications on a power system.

The Regenesysª system is based on regenerative fuel cell technology, (sometimes known as redox flow cell technology). Two electrolytes flow through the fuel cell on either side of an ion exchange membrane. By applying a voltage across the electrolytes they change state and become “charged”. The “charged” electrolytes pass out of the fuel cell to be stored in tanks. Just like a rechargeable battery, the process can be easily reversed. The “charged” electrolytes flow back through the fuel cell and electricity is produced.

The two electrolytes are concentrated solutions of sodium bromide and sodium polysulphide. The technology is environmentally benign, modular, comparatively easy to site, and separates the power rating from the energy storage capacity. These features make it suitable for energy storage applications in the 5 – 500 MW range which require storage times from fractions of a second to 12 hours or more.

Following successful trials of a Regenesys pilot plant at a power station in South Wales, the company will build its first full scale commercial plant at Didcot in Oxfordshire. Detailed designs are now complete for up to a 15 MW and 120 MWh utility scale energy storage plant. The plant would be housed in a low-rise building, occupying a compact site conservatively estimated at less than 0.5 hectare (1.2 acres). This generic design could be used for a number of applications within the power industry.

The total installed capital cost will be approximately $150/kWh. With continued technical improvements, National Power has set an eventual target price of US$80/kWh.

A storage plant with these cost and performance characteristics will provide significant technical and financial benefits in the operation of a network, from more efficient use of plant (generation, transmission and distribution), and from improved system performance. Storage can also significantly enhance the value of electricity produced by renewable generators, such as wind turbines.

The only available existing large-scale energy storage techniques are pumped hydro or compressed air energy storage, which have severe geographical limitations. Regensys would provide a real alternative. Other energy storage techniques such as batteries, flywheels, superconducting magnetic storage and supercapacitors have different capacity characteristics, and are not well suited to large scale applications.

National Power has formed a new business unit within its Commercial Division to develop the Regenesys technology in the UK and overseas.

Contact: Barry Davidson tel 011-44-1235-444-991

(I also have a PDF file of their brochure)

==== Some Additional Technical Details ===============

Regenerative fuel cells are a separate class of electrochemical device, which have inert electrodes acting only as an electron transfer surface. The electrodes do not take part in the electrochemical process and so do not limit the energy storage capacity of the regenerative fuel cell. This approach allows the complete separation of power, determined by the module’s electrode area, and energy, determined by the storage tank volume.

There are many electrochemical couples that have been assessed for use in flow battery systems. The Regenesys system uses electrolytes of concentrated solutions of sodium bromide and sodium polysulphide. These salts are readily soluble and present no adverse hazards in handling or storage. They are abundant and available at the necessary degree of purity at moderate cost. The use of other bromide and sulphide salts was investigated during the development phase, but the increased electrochemical efficiency would not necessarily repay the additional costs of the alternatives.

The simplified overall chemical reaction for the cell is given by:

3 NaBr + Na2S4 2 Na2S2 + NaBr3

The conversion of electrical to stored chemical energy and back again can be repeated indefinitely with high turnaround efficiency. There is no memory effect associated with the specific electrochemistry of the Regenesys system, and a full charge/discharge cycle can be completed without limitation of a theoretical maximum depth of discharge.

When commissioned the plant will have the ability to start up in less than 10 minutes or, if held in stand-by mode with the modules filled with electrolytes, in seconds. The plant will have a high rate of dynamic response. When running, the plant will be operated fully connected to the grid, capable of turning from a state of fully charging to fully discharging or any state in between in the order of 0.02 seconds. This performance makes the plant suitable for a number of ancillary service applications such as voltage control and frequency response. In stand-by or shutdown mode there is no self-discharge of the electrolyte stored in the tanks.

The Power Conversion System (PCS) provides the interface between the AC network electrical supply and the variable operating voltage of the DC modules. The four quadrant converter system is designed to transfer both reactive and real power simultaneously and independently from each other.

The PCS allows the operator to select from a wide range of operating modes.
– Pre-defined schedule
– Load following
– Voltage control mode
– Frequency regulation
– Power System Stabilisation
– Constant VAr
– Constant AC power
– Self-commutated to operate as a UPS, or to provide Black Start

And, practical peak shaving and dispatch optimization on networks, which has been limited by the availability of suitable technology.

UK Renewables Review

(Renewables are being taken up faster in Europe than in the US, with commitments at all levels of government and industry, so it’s important for us to follow developments there closely.)
The UK Department of Trade and Industry has some very interesting stuff on its website, at:

In particular, they issued a major report recently. Here is a notice about it.

In March, Energy Minister John Battle set out the Government’s blueprint for the future of renewables, reaffirming its commitment to developing the industry and boosting research and development expenditure to £43 million over the next three years. Launching the Consultation Paper “New and Renewable Energy ? Prospects for the 21st Century”, which reports on the outcome of the Government’s review of new and renewable energy policy, Mr Battle said:

“The Renewables Review paper demonstrates that there is tremendous potential for renewables to become a fully competitive part of UK energy supply. The Government intends working towards a target of renewable energy providing 10% of UK electricity supplies, cost-effectively, as soon as possible. This report seeks views on the issues raised to enable the Government to frame its future policy. I look forward to receiving those views and plan to make a further announcement about our way forward in due course”.

Responses should be made by 28 May 1999 to Neil Hornsby, Energy Technologies Directorate, DTI, 1 Victoria Street, London SW1H 0ET. Copies of the Review are available from: DTI Publications Orderline, Admail 528, London SW1W 8YT, Tel: 0870 1502 500, Fax: 0870 1502 333, e-mail: The document is also available on the Internet at:

– >>
At this link, there are pdf and word downloads available of the report itself. Also provided — a 277 page pdf document: “Supporting Analysis for New and Renewable Energy”, which appears to be a very comprehensive report on all types of renewables.

Found in: NEW REVIEW, ISSUE 40, May 1999
The Quarterly Newsletter for the UK New and Renewable Energy Industry

Also Recommended:
Canadian Association for Renewable Energies Association
Their free weekly email newsletter is a great source of information.
(This is where I learned of the item above)

Progress: Nortel/Norweb UK Digital Powerline

Last Oct 8, Nortel and Norweb in the UK made a big announcement about a breakthrough in putting data over the powerline at up to 1 megabit/sec. UFTO Notes on Oct 8 and 22 supplied information that was available at that time. (See the UFTO Database-do a search for “nortel” to get a copy of these two notes.) In mid December, another press release was issued on the test being run at a school in Manchester, England. The system is operational.

Understandably, UFTO’s initial query to Nortel back in October got lost in the chaos that followed their first announcement. Now with a recent follow up, we have new information and a unique opportunity to get involved at the front end of this remarkable development.

1. More details about the system now officially named “Digital Powerline” are available on Nortel’s website at:

2. Nortel and Norweb will announce in the coming weeks how they intend to pursue worldwide commercial deployment of this product.

3. Nortel North America, headquartered in Atlanta, has a group that sells networking equipment and services to the electric utility industry. This group has lined up two US utilities for a preliminary study of their distribution system configurations, to be able to begin the process of understanding the best prospects for deployment — i.e. markets, locations, niches, and technical issues, etc.

The system serves as the communications link to the customer’s premises, and provides an “always on” internet connection. A small box next to the meter connects via coax cable to the customer’s computer. The ISP would connect to the utility’s backbone which connects via fiber or other dedicated high-bandwidth transport means. As the website explains, one big issue for N. America is the number of customers per distribution transformer (8-10, vs. 100 or more in the UK), and the possible need for some kind of bypass technology.

More technical details beyond what appears on the website can be made available only under a non-disclosure.

The Nortel group in Atlanta would welcome the opportunity to enter into discussions with UFTO utilities. Contact: Barbara Warren, 770-708-5117,

Energy Storage Assoc. Meeting

Energy Storage Association (ESA) Fall Meeting
“The Value of Energy Storage in a Restructured Utility Market”
Sacramento, CA
November 18 -19, 1997

((An UFTO Note on Nov 10 gave the original agenda for this meeting.))

*** –> SPECIAL OFFER <– ***

This one time, the ESA is offering to send a free copy of the full proceedings to prospective members, together with their membership solicitation package. Membership in ESA is a good way to stay in touch with developments in utility storage, and a year’s company membership is only $1500.

To request the package and proceedings of the November meeting, contact (please tell them UFTO sent you):

TEL: (301) 951-3223
FAX: (301) 951-3235

E-MAIL: John Hurwitch, Executive Director,


(more details on request–and in the Proceedings)

–> Overview of the Market:
The goal of ESA and the DOE Utility Storage program is to build market volume for storage systems. Utilities are proving to be a very tough market for battery storage, despite a strong benefit/cost story. One hypothesis is that the benefits are scattered among different stakeholders (even within a utility), with no single part being big enough by itself. Nobody is in a position to put it together, and restructuring is making the situation even worse, as the walls go up inside utilities. Also, utilities say they have no money, and want the first cost to be very low, regardless of life-cycle considerations. Meanwhile, big needs are looming, especially on transmission systems, but nobody seems to own the problem or is in a position to make the investment.

Vendors are offering turnkey systems for various applications and markets, but there are very few orders, and those are mostly for very special situations, e.g. in Alaska (remarkable success stories). Vendors are getting very discouraged, and may be close to throwing in the towel.

Is the problem with the Technology? Marketing? Or do utilities “just not get it?” Or, are the proponents wrong in their view that storage is an idea whose time is overdue, and that it’s largely a matter of “education”? In 1996, DOE and Sandia visited with over two dozen utilities to try to understand the industry’s views on storage. Results were recently published: “Report on the Energy Storage Systems Program Executive Meetings Project” SAND 97-2700, November 97. However, more dialogue with the utility industry is still needed, to get to the bottom of these questions.

The ESA has proposed a flagship project called “Storage 2000,” as a joint program with DOE to stimulate and accelerate development, with a goal of 200 MW of project commitments by the year 2000. Applications are to include renewable, distributed, generation/transmission (ancillary services), and customer systems.

–> Energy Storage in the UK
The closer storage is to the customer, the better. Anthony Price, of National Power, UK, compared batteries to warehouses for “just in time” distribution, where it’s well known that you put storage only in one place in the system, close to the customer. He showed an analysis of the bulk market hourly price over time. Even with big differences between on and off peak wholesale prices, you can’t win by buying off-peak and selling on-peak. Not only are there roundtrip (storage) losses, but you’re also fighting the spread (sell at the bid price, buy at ask). What you’d be selling is capacity, and there’s currently an excess.

The farther down the distribution chain you are, more distribution costs are built into the price of goods, so storage has more value. However, whoever owns the storage controls that value. “If the customer owns the storage, then the rates are wrong”.

–> Uninterruptible Power and Power Quality
While utility storage isn’t moving, UPS and P/Q applications are a very strong market (a lesson there somewhere?). There are still issues, however. Though vendors have products, there’s often insufficient understanding of what a “disturbance” really is. For example, they may design for a 3 phase symmetrical fault, which rarely occurs. Phase shifts and waveforms need particular attention. Too often, products need to be redesigned in the field.

There are several interesting systems using steel flywheels: – International Computer Power — steel flywheel in a 100 kVA motor genset to provide ridethrough, successfully demonstrated for two years at a Hewlett Packard site, dramatically reducing diesel backup starts. – Holic Power Protection — 100’s installed worldwide. Diesel generator and flywheel combination where the flywheel dynamically adjusts itself to maintain constant generator speed. 1250 kVA unit runs about $1.1 million. Without the diesel, it can provide short term ride through. – Active Power, Austin TX, has been issuing press releases lately. Modular pancake unit provides 400kW for 5 sec, for short discharge P/Q applications.

In “new” technology (composite) flywheels, Beacon Power presented their plug-replacement for batteries in UPS systems. The 1 kW, 2kWh unit goes directly on the DC bus. Beacon is a joint venture between SatCon and Duquesne. They expect to be in production by the end of ’98, with beta tests in mid year.
–> Renewables and Storage
Solar and Wind energy systems need storage, particularly in remote/village power applications. The opportunities are huge, particularly to supply the 2 billion people in the world with no electricity, and to displace diesel fuel consumption. A number of programs are trying to come up with reliable modular integrated systems (hybrids with diesel, solar or wind, and batteries). Batteries are often blamed as the weak link in renewable energy systems (right along with inverters), but the blame may be misplaced–often the wrong type of battery is installed by local people.

The President’s “Million Solar Roof” initiative is beginning to be felt, though this may not necessarily imply much use of storage. SMUD has a huge commitment to renewables, and are just now beginning to consider the potential benefits of storage in that context.

The first major project under Storage 2000 is to be the “Renewable Generation and Storage ” (RGS) project. Partners will be selected by formal solicitation process in 1998 for design, development and testing of a prototype integrated system with a PV array, inverter and storage, ready for customer use. International opportunities exist for “Remote Area Power Systems” or mini-grid systems. Funding is available, and local governments are motivated, e.g. in Latin America. The Solar Energy Industry Association has information. ( ).

–> Texas Energy Storage Technology Institute (ESTI)
This is a coordinated research program involving all the universities in Texas, funded in part by the Texas Energy Coordinating Council, a state agency. ESTI is doing work in capacitors, batteries, and particularly high performance flywheel systems for railroad applications. DOT and DARPA funding support the Advanced Locomotive Propulsion System, which includes a 3 MW Allied Signal gas turbo-alternator, and the University-developed 167 kwh flywheel for braking and acceleration. The idea is to provide an alternative to electrification of railroad right of way. ESTI wants to encourage synergies between stationary and mobile storage systems. Contact John Price, 512-471-4496, 512-232-1888 (direct),, http:/

–> Key Note Speaker

Separately, Pramod Kulkarni of the CEC outlined the priorities for storage in California, seen as a “strategic” area under the public benefit R&D program.

Telecomm over the power line in UK

(I don’t normally just pass along press releases, but this one looked too important and I didn’t want to take the chance that you would miss seeing it.)

Wednesday October 8 4:55 AM EDT
Company Press Release

Nortel (Northern Telecom) and Norweb Communications Achieve Technology Breakthrough That Will Open a New Wave of Internet Growth

LONDON, Oct. 8 /PRNewswire/ – Nortel (Northern Telecom) and Norweb Communications, a business unit of United Utilities plc. of Great Britain, today announced that they have developed jointly a new technology that allows data to be transferred over electrical power lines into the home at speeds of more than one megabit per second-up to 10 times faster than ISDN, currently the fastest generally available speed. The breakthrough has the potential to open a new wave of demand for Internet services in the UK and Europe.

Nortel has developed the technology at its European Research and Development laboratories in Harlow, UK, in co-operation with Norweb Communications. Recent trials on the Norweb Communications network have been completed successfully and the technology is available for deployment.

The technology, which enables electrical companies to convert their power infrastructures into information access networks, will be initially marketed in the UK, Europe and Asia Pacific.

It allows electrical companies to provide a service that solves the three major problems facing international Internet market acceptance-access to consumers’ homes, data transmission rates and capital cost:

– By giving customers access to the Internet through their existing electrical supply system, the technology is available to virtually anyone. It offers permanent on-line connection with the potential for lower charges;

– The new technology enables data to be transmitted at rates of more than one megabit per second by using a patented technology that screens the data from electrical interference on the host power line, a long sought-after goal in telecommunications;

– Investment costs for the electrical companies are low compared to those envisioned for other broadband data access systems. Due to the nature of this technology, it can be rolled out in discrete, targeted phases. Utilities not wishing to operate data services also have the option of charging a right-to-use fee to an operating company for accessing their plant. End users require a computer card comparable in cost to a conventional ISDN terminal adapter, but offering 10 times the peak bandwidth.

The new technology will enable the introduction of Internet-based applications such as electronic commerce, teleworking, web broadcast media, entertainment and Internet telephony on a mass market scale.

The two companies have been working together on this development for the last three years and it is subject to a number of patents filed by Nortel and Norweb Communications. Norweb Communications is widely recognized within the power sector as a leader in research into broadband communications over power lines, having started work in this area in 1990.

Electricity utilities in Europe and the Asia Pacific region have already expressed significant interest.

Peter Dudley, a vice-president of Nortel, comments: “The rate of Internet take up and the volume of data traffic carried over the Internet has been one of the most striking business developments of the current decade, but speed of access remains a bottleneck for most users. As one of the first practical low-cost answers to the problem of high-speed access to the Internet this new technology will unleash the next wave of net growth.”

Mark Ballett, Managing Director of Norweb Communications, comments: “Norweb Communications has championed the use of electrical networks for voice and data services for several years and we are delighted to now be in a position to announce the launch of the first commercial products. This technology will allow us to use existing infrastructure to establish a strongly differentiated service offering in the northwest residential and small business market.”

Nortel will be opening a conformance center in Harlow, UK, for hardware and software suppliers who are interested in certifying their products for use on this new service.

Norweb Communications, part of United Utilities plc, provides an extensive range of advanced voice and data services and has achieved significant success in providing resilient networks for businesses throughout the northwest region of the UK. The company plans to use power line technology to provide public access networks for residential customers in the region.

United Utilities has combined capability in electricity, gas and telecom. This new technology will strengthen its competitiveness as a multi-utility service provider.

Nortel had a 1996 turnover of $US 3 billion in Europe, operating both independently and through its joint ventures with the Lagardere Group in France (Matra Communications and Nortel Matra Cellular), Olivetti SpA in Italy (Sixtel) and Daimler-Benz Aerospace AG in Germany (Nortel Dasa Network Systems). The company employs approximately 16,000 people across Europe in Research and Development, manufacturing and sales.

Nortel works with customers worldwide to design build and integrate digital networks – for information, entertainment, education and business – offering one of the broadest choices of network solutions in the industry.

Nortel had 1996 revenues of $US 12.8 billion and has approximately 68,000 employees worldwide.