Energy Storage Assoc Meeting Notes

Here are some notes from the recent meeting of the ESA, here in the SF
bay area. The ESA website will be posting additional information.

Energy Storage Association
2000 Annual Meeting

“Cleaner, Greener Power through Energy Storage”
6-7 April 2000
Pleasanton, CA


Finally, energy storage appears to be breaking through, across a broad front. There are about 100 MW of pending purchases for systems in the US, and a comparable amount in Europe. This new success isn’t limited to one technology either, but is spread across many different ones, from flywheels to SMES to advanced Pb Acid to “flow” batteries. Applications range from small to large, from local UPS/power quality to grid support systems.

This meeting had as its theme the environmental implications of storage, noting the synergies with renewable power (e.g. to improve its dispatchability and application), and how storage also can improve the environmental performance of conventional plants.


Flow Batteries

Flow batteries in particular are emerging strongly; four companies presented different chemistries and product niches.

In these systems, two electrolytes flow through a reactor, which is similar to a fuel cell, on either side of an separator membrane. When a voltage is applied across the reactor, the electrolytes change state and become “charged”. The “charged” electrolytes pass out of the reactor to be stored in tanks. Just like a conventional rechargeable battery, the process can be easily reversed. The “charged” electrolytes flow back through the reactor and electricity is produced. The technologies are environmentally benign, modular, comparatively easy to site, and separate the power rating from the energy storage capacity. They also appear to be free of the charge/discharge management issues that most battery chemistries suffer from, i.e. they can be fully discharged, and have no standby self-discharge losses (i.e. when the circulating pumps are turned off). Manufacturing and material costs are relatively low, and system costs will drop as the number of installations increases.

— Regenesys — Large Scale Utility Energy Storage — sodium bromide and sodium polysulphide electrolytes. An “electricity warehouse” reference design is based on 120 MWh with 10 hour discharge, max rated output 14.75 MW. Other configurations (5 – 500 MW) are possible. First plant at advanced stage of planning on a power station site in the UK. The first N. American “follow-on” installation is in advanced discussions. A transportable/containerised unit is suggested at 20 MWh, 2MW. (

— Pinnacle VRB Ltd — Renewable and Remote Applications — vanadium (in various charge states). Invented at Univ of New South Wales, Australia. Licensed to Sumitomo and Mitshubishi in Japan. Sumitomo has developed collapsible storage tanks that can go through doors and manholes, enabling installation in existing structures. (High time-of-day rate differentials make diurnal peak shaving attractive.) Installation at SDGE as part of EPRI DR test program. A unit at a park hostel in Australia is 20 kw/120 kwh, part of a remote power system. Another on King Island is 100kw/1800 kwh supports a minigrid and drastically reduces diesel fuel and operating costs. (

— Powercell — Zinc-Flow™ uses zinc bromide and polybromide solutions. Their standard unit is the PowerBlock, 100kW/100kWh, in one self contained package complete with power electronics. It is on the market, to date mostly through Williams Energy, and the company is ramping up production to meet the demand. (

— Cellennium — also uses vanadium. This Thailand based company is developing a wide range of applications, from small to large. (


Keynote Address: * Renewables, Distributed Generation and System Reliability in a Restructured Electric Supply Industry – Gregg Renkes, The Renkes Group, Ltd.

Renkes was staff to Senator Murkowski for many years, and directly involved in many of the congressional hearings on the energy industry. He gave a detailed view of how the players line up in Washington, particularly as to how the elections will impact restructuring legislation in the near future. Starting from a historical perspective (cold war, White House and Congress controlled by opposite parties), he uses various clues to how Gore and Bush’s views on energy will play out (in the closest race in recent history), and concludes they’re very similar. The current administration’s proposal, and what’s been done in Texas both point to restructuring, market mechanisms to deal with emissions, renewable standards, etc. In Congress, there’s also more agreement than disagreement, and the states’ speed on restructuring is pressuring Congress to do something sooner rather than later, regardless of election results. Grid reliability, and shortages expected this summer are high profile reasons for action. Overall, conditions are looking increasingly positive for distributed power, renewables, and storage application.


* Energy Storage and Renewable Energy, BPA’s Perspectives
Mike Hoffman, Bonneville Power Administration

BPA is espousing an “EnergyWeb” concept, and see storage as an important element alongside distributed generation and renewables. In conjunction with wind, for example, storage can make it possible to dispatch wind power in the large flat blocks during peak demand, and displace carbon-based generation in the process. Wind power could also be bid into hour-ahead and week-ahead markets if the storage system has a high enough discharge rate. Customer side storage becomes relevant if there are demand charges–and retail access. Larger system configurations depend on local market structures. On the transmission system, storage presents many potential benefits, no one of which is enough by itself to justify the cost, but taken together could do it. Storage will be easier to site than new lines; it can help with congestion management, increase transfer capability, and replace contingencies. Transportable systems would overcome fears of stranded investment. Fast systems (e.g. SMES) can help with stability.


* IBERDROLA’s Technology Demonstration Centre
Jesus Garcia Martin, IBERDROLA

This center supports the generation and other business units of Iderbola, one of the four large utilities in Spain. The only such facility in Spain, it evaluates and tests new technology, does technology transfer, and tries to reduce the time it takes to introduce new technology. In renewable energy, they have PV arrays, fuel cell demonstrations (one with Ansaldo in Italy is a molten carbonate), studies in biomass, thermal solar, wind and hybrid systems. There is also have a 2 MW battery storage system, operating for the last 4 years.


* Power Quality Management as a Green Technology; Imre Gyuk, DOE

Storage is important for reliability and economic competitiveness, and it also plays a role as a green technology, by virtue of its ability to increase the potential of (intermittent) renewable energy sources by making them more dispatchable, and, for example, reducing/optimizing use of diesels in off grid or microgrid settings.


* Flywheels for Renewable Energy and Power Quality Applications
Don Bender, Trinity Flywheel Power

(There was also a tour of Trinity’s plant nearby.) As lower tech flywheel (i.e. steel) systems are opening the market, high speed carbon composite systems are making steady progress, though they’re taking longer than anticipated. There’s been a lot of hype over the last 10 years, and only a small number of contenders are still around. Programs were underfunded, and had too much of a component, not system, focus. Also, requirements for vehicular applications were too severe for the first step.

Trinity’s “electromechanical battery,” as they like to call it, uses a 9 inch diameter rotor. Turning at 40,000 rpm, it will deliver 50 kW for 20 sec. Other configurations offer 100kW/15 sec to 250kW/3 sec, and 700kW/5 sec. Installed on a DC bus to add or remove power as needed, it can deliver energy, or power or both, from a compact package – power density (of the motor/generator and power electronics) starts at 5 kW/kg. The state of charge is always precisely known from the rotational speed. The balance of plant has turned out to be a bigger challenge than originally expected, and the power electronics have very special requirements. Flywheels should have an advantage for short duration power quality applications. Safety concerns have been addressed by a collaboration among most of the developers. You need either containment or rotor integrity, not both. Trinity has focused on rotor integrity, through extensive overspeed/burst testing.


* Battery Energy Storage for Residential Photovoltaic Systems
Bill Brooks, Endecon Engineering

Over 75% of the 299 PV systems installed under CEC Emerging Renewables Buydown program in the first two years of the program include some amount of battery storage. (Even higher percentage among residential projects). The CEC Buydown does not apply to the battery portion of the systems. (even though several attempts were made to include batteries). Battery options are generally preferred and actually help sell the PV system by providing firm backup power capabilities. Batteries are here to stay in this market.

Most appropriate battery for this market is the Valve-Regulated Lead-Acid (VRLA) battery. Advantage—Low maintenance, good performance Disadvantage—Higher cost, intolerant of high temperatures or improper regulation voltages.

Enclosures need very little ventilation. Best if placed in garage or in an outdoor enclosure (in shade and/or conditioned to prevent high temperatures). Building inspectors are unfamiliar with reviewing battery installations; their requirements vary from plywood boxes to explosion-proof enclosures with four-hour fire ratings. Very few batteries or battery enclosures have listings or recognitions by testing labs. PV is blazing the way for a whole series of backup power options for residential and commercial customers.

The Trace 5548 Power Module has a5.5kW ac rating, 44-60V dc input, 120Vac output — Batteries and controls all in the same cabinet, up to 12 kWh in storage cabinet.

More Battery is ALWAYS better


* Utility Evaluation and Demonstration of Dispersed Subsurface
Compressed Air Energy Storage, Dale Bradshaw, Tennessee Valley Authority

A 300 MW CAES site got pretty far in the planning stages in the early 90’s, but the plant was never built. Now TVA is considering a smaller scale system (10-20 MW; 6-10 hours) to be used close to the customer to help relieve transmission congestion. The compressed air field would consist of 3-4000 ft of 5-foot diameter gas pipe, laid out in any pattern convenient for the site, e.g. under a farmer’s field. The CT’s would always be available, even if the storage was exhausted, and while using the compressed air, plant output would not be sensitive to ambient air temperature, and would be a low cost source of spinning reserve, with rapid hot or cold start. Operating cost benefits compared with a CT become significant under higher gas prices.


* Lithium Ion Batteries for Energy Storage Applications
Jim McDowall, SAFT America
Lithium Ion is not just one kind of battery, but refers to a whole family of battery materials and chemistries, with a wide range of characteristics. First proposed in 1990, and first shipped in 1993, they are now in 1/2 of all portable devices. Saft and others have been working on a large scale version for EV applications. Lithium is the lightest metal and offers the highest voltage. With no water present, there’s no problem with electrolysis during charging. SAFT’s battery has lithiated cobalt oxide as the positive electrode, lithium intercalated in graphite as the negative electrode, and the electrolyte consists of LiPF6 salt in an organic solvent. Lithium-Ion batteries must be protected from high temperature (they’ll burn over 150 deg C), overcharge, overdischarge, and over voltage. Therefore each cell must have its own built-in electronic monitoring and control. The batteries provide good cycling, high power, and deep discharge. They’re in pilot production and should be available commercially in 3 years. Though the initial cost is high, this will be very dependent on volume (as with so many new technologies). Life-cycle cost should eventually match Lead-Acid batteries.

* Molten Salt as an Energy Storage Medium
Hugh Reilly, Sandia National Lab

The Solar II plant, closed down over a year ago, used molten salt to transport heat from the tower to heat exhangers, making steam for power generation. Adding 2 large storage tanks effectively decoupled the collection of energy from the generation of electricity, with 105 MWhr of storage, at 97% efficiency, and thus enabling anytime dispatch of solar electricity. The salts solidify at 430 deg F, so the “cold tank” must be kept above that temperature. A new plant using this approach, “Solar Tres”, is under construction in Spain by a consortium that includes Boeing and Bechtel.


* Annex XV: Energy Storage and Renewable Generation: The New Opportunity
John Boyes, Sandia National Lab
The International Energy Agency (IEA), which is an offshoot of the OECD, sponsors a series of research programs and working groups. For a complete list, see “Implementing Agreements” at

Annex XV is the successor to Annex IX, and both of these are under a broad category that covers all forms of storage for energy conservation.
For details, see

An acrobat document gives an overview ( The program scope will be determined at a meeting in October, with work to begin in November.

The objective is “to move storage systems towards commercial market implementation, via the mechanism of technology and applications demonstrators. Whilst it is beyond the scope of Annex 15 to implement an actual demonstration project, it is fully intended that much of the necessary groundwork will be covered within the project to make a demonstration project the next logical step in electrical energy storage system market development.”



Jon Hurwitch – His firm Switch Technology has merged with RK Sen to form Sentech

Evonyx – Ian Grant is new to ESA and a new employee of Evonyx, announced a major investment by Niagara Mohawk in their company. Evonyx has a new type of Zn-Air battery which can be recharged or physically refueled with solid plates or tapes. They forsee applications from AAA size to multi-MW. (

Trace (Trace Technologies and Trace Engineering) announced their merger with Xantrex.

Brad Roberts explained that Omnion had been acquired by S&C Electric, and that they were filling commercial orders for the PQ2000.

Anthony Price and Joe Iannucci observed that lots of money has been spent on reducing the cost of storage technology, nothing has been spent on increasing its value, e.g., integrating it with renewables.

Steve Eckroad summarized recent developments at Golden Valley Electric, Fairbanks, where they’re in the last stage of bidding for a major BESS. There are 3 finalists- ABB, GE and Siemens, each teamed with a particular battery. An award is expected in September.