VRB technology comes to the fore

By Nigel Blackaby

The Holy Grail of cost-effective, bulk energy storage has been pursued in many different ways, but one system is showing particular promise. The Vanadium Energy Storage System (VESS) is about to be installed for the first time in a commercial operating environment in North America, following successful trials in South Africa.

Canadian energy technology company Vanteck VRB Technology Corporation has developed the Vanadium Energy Storage System (VESS), a Vanadium Redox Battery-based storage device. The Vancouver, B.C-based company has, under licence, rights to develop, market, manufacture and sell portable Vanadium Redox Battery applications worldwide.

In the power industry, energy storage can provide ‘ride-through’ for momentary outages, and extended protection from longer outages. Without it, power producers require expensive surplus generating and distribution capacity to meet peak demand. Coupled with advanced power electronics, storage systems can reduce harmonic distortions, and eliminate voltage sags and surges. When used in conjunction with renewable resources, energy storage can increase the value of photovoltaic (PV) and wind-generated electricity, making supply coincident with periods of peak consumer demand. For utilities, energy storage systems can be used to follow load, stabilise frequency, and manage peak loads.

Fig 1. VRB technology: an electrochemical redox reaction produces a current, providing power to the electricity grid
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The California-based Electricity Storage Association (ESA) estimates the world market for batteries to be about $15bn each year. It believes that industrial batteries, as might be used in uninterruptible power supplies, power quality applications, standby and reserve batteries, amount to $5bn each year.

Chemical storage

Vanadium Redox Battery (VRB) technology was first developed and patented by the University of New South Wales in Australia. It is referred to as a reduction/oxidation (redox) flow battery. Energy is stored chemically in two forms of ionic vanadium in acidic liquid electrolyte. The VRB is made up of a number of flow cells, also known as ‘stacks’, and the electrolyte is pumped from separate storage tanks into each of the flow cells.

The two different forms of the electrolyte remain separated by a Proton Exchange Membrane. In doing so, one form of the ionic vanadium is oxidized and the other form reduced with the resulting current collected by electrodes and available to an external circuit. The electrochemical reaction is reversible, so the VRB can be charged and discharged. The concentration of each ionic form of the vanadium electrolyte changes as the VRB is charged and discharged with electrical energy being converted to chemical energy and vice-versa.

The battery operates on the V(4+)/V(5+)//V(3+)/V(2+) redox couples and produces a nominal cell potential of approximately 1.25 V, depending on the concentration of vanadium. As with other flow batteries, useful terminal voltages are achieved by series connections of many cells into the stack. The amount of power available is related to the stack voltage and the current density established across the membrane, while the time (or ampere-hours) available depends only on the supply of charged electrolyte to the stack.

VRB technology has been under development since the mid-1980s but until relatively recently its application has been limited to Japan, where Mitsubishi Group operates a load levelling VRB system connected to the Tokyo grid. Advancements in the manufacture of electrolyte and the cell stack system have opened up a wider range of applications and have made commercial exploitation of the technology feasible.

Since Vanadium Redox Batteries operate at normal temperatures, they offer a safety advantage. The VRB has a low ecological impact using plastic electrodes and contains no heavy metals such as lead, nickel, zinc cadmium etc., which alternative battery systems usually contain. These materials all have potential environmental impacts both during production and upon disposal. The electrolyte used in the VRB has an indefinite life, and there are no disposal issues.

VESS is a proprietary advancement of the basic VRB technology. Vanteck believes it has achieved a commercial application by incorporating the VRB technology into its flexible and modular-based Vanadium Energy Storage System. VESS integrates the VRB into a practical energy storage system, in which the design and operating characteristics of the VRB are optimized and integrated with automated intelligent control and operational management electronics. The battery is monitored and controlled in order to achieve a performance suited to the customer’s need.

Going commercial

As a new technology, technical credibility and performance against existing technologies had to be established and an important user-based field trial of a VESS incorporating a 250 kW/520 kWh VRB has been undertaken in South Africa – the first such large-scale commercial trial outside Japan.

The trial brought together three interested parties: Vanteck; Highveld Vanadium and Steel Corporation, who have access to significant reserves of vanadium needed for the electrolyte manufacture; and Eskom, the national electricity utility of South Africa. As the fifth largest electricity generator in the world supplying 60 per cent of continental Africa’s entire electricity demand, Eskom has to address the issues of power quality and reliability. These are also practical considerations for Highveld, one of Eskom’s largest customers. The project, known as the Stellenbosch VESS trial, is part of an evaluation of options and solutions for power quality issues currently under consideration by Eskom.

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The VRB system installed for the Stellenbosch VESS trial was designed to show the versatile configuration and operation of VESS, with the single installation demonstrating applications ranging from sub-second uninterrupible power supply (UPS) ride-through capability through to power quality and emergency power back-up.

Vanteck undertook the installation for the TSI division of Eskom at the University of Stellenbosch, Cape Town. It was commissioned in September 2001 and followed Vanteck’s business strategy of reducing the VRB and VESS to core components and developing low-cost supply paths for each element in order to meet baseline cost targets through aggregation. System components for the TSI/Eskom VRB-VESS system were obtained from various sources reflecting an international effort to commercialize the technology.

The six 42 kW 100-cell stacks were purchased from Sumitomo Electric Industries. Vanteck/Highveld Vanadium and Steel produced the electrolyte in South Africa at an electrolyte pilot plant established in Highveld’s Witbank facility to a purity level specified by the stack manufacturer. Vanteck/Highveld are able to implement and scale up bulk vanadium electrolyte manufacture going forward. Eskom’s 250 KVA shunt connected Dynamic Power Quality Compensator (DPQC) was used as the PCS bi-directional inverter. Vanteck developed its proprietary VESS hardware and software along with technical consultants, Telepower Australia, under the guidance of Dr John Hawkins who is both a principle of Telepower Australia and a director of Vanteck.

As an electrochemical system, the VRB can achieve high voltaic and coulombic efficiencies. The performance of the technology in the field trial was outlined in papers presented at the 21st International Telecommunication Energy Conference (Intelec 2001) in Edinburgh in October 2001 and to the Electrical Energy Storage – Applications and Technology conference (EESAT) in San Francisco in April 2002.

Fig 2. Typical charge and discharge curves for a 100-cell VRB stack
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Typical voltaic efficiency of 92 per cent and coulombic efficiency of 96 per cent were reported. The individual stack performance was verified at the place of manufacture prior to shipping. The typical discharge and charge curve for one of the 100-cell stacks is shown in Figure 2. The profile is similar in character to the discharge of a typical lead-acid battery.

The benchmark stack performance of each of the six stacks at the specified 400A operational current measured over three consecutive charge-discharge cycles is listed in Table 1. At a discharge current of 400A, the stacks used in the Stellenbosch VESS trail all delivered in excess of 42kW DC power during discharge and exhibited a consistent overall DC energy efficiency of 82-85 per cent.

Advanced knowledge

The recently concluded trials have proved to be a success, according to Vanteck. “Aside from some very minor hiccups such as fibre glass fracture, the results have been better than expected – almost flawless,” said Greg Pearson, head of investor relations for Vanteck. “The technology performed extremely well and, as a result, Eskom is very happy,” he added.

Fig 3. Electrolyte storage tanks at Vanteck’s Stellenbosch VESS trial in South Africa
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Dr John Hawkins told the EESAT conference that the trials had advanced Vanteck’s knowledge in the packaging and modular design of the VRB VESS and improved running costs and refining applications.

“The trials have resulted in the prospect of better energy density,” Vanteck CEO Don Nicholson told PEi. “By improving the kW stored/litre electrolyte ratio, we can reduce the amount of electrolyte needed and, as a result make it cheaper to operate,” said Nicholson.

Following the success of the Stellenbosch trial, the commercial breakthrough for VESS in North America came in January this year when PacifiCorp, a subsidiary of UK utility Scottish Power, placed an order with Vanteck for a 250 kW-2000 kWh (eight hour) system. PacifiCorp is responsible for one of the most extensive transmission systems in the US and has a service area of more than 217 300 km, supplying electricity to 1.5 million customers.

The VESS unit, which is modular and relocatable in design, will be used by PacifiCorp to supply peak power capacity (charging in off-peak hours) and provide end of line voltage support (supplying up to 250 kVAR of reactive power) in a remote area of southeastern Utah. Installation and commissioning of the VESS unit is scheduled for completion by the end of June, in time for peak summer demand. “Due to its modular design, the system can be deployed remarkably quickly,” added Hawkins.

PacifiCorp will use the stored energy and voltage support available through the VESS unit to maintain a reliable service in the area while deferring the need to build a new substation. Regulatory obligations meant PacifiCorp needed a quick fix. The VRB/VESS will provide an immediate temporary power solution in an area where environmental constraints exist. The portability of the unit means that it can be moved to another location as needed in the future.

Critical Storage

Two shipments of vanadium electrolyte for Vanteck’s PacifiCorp VESS unit have already been delivered to the US from Highveld Steel and Vanadium’s facilities in South Africa.

Commenting at the time of the order, Rodney Duncan, the then President and CEO of Vanteck, said, “Cost effective large scale reliable energy storage is becoming critical for highly reliable AC and DC power supply, particularly at the distributed end of the market. There is a growing demand for uninterrupted back-up power for ride-through, peak shaving, UPS and quality power which the Vanadium redox energy storage technology addresses.”

The endorsements by PacifiCorp and Eskom are vitally important both in regards to the future application of the VRB VESS technology and for Vanteck’s prospects. “The PacifiCorp order is hugely significant. It is ‘proof of concept’ and it is important that it goes well,” said Pearson. “Utilities are conservative by nature and will be viewing closely the project although discussions are already underway with other utilities for similar installations,” he commented.

Fig 4. VRB/CESS cell stacks at the Stellenbosch University installation
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Confidentiality agreements prevent Vanteck from revealing the value of the order but the deal includes some shared costs and an intention for further orders to be placed in which the benefits of economies of scale will be shared 50/50 between Vanteck and PacifiCorp.

Despite the success of the field trial, Vanteck shareholders have not, of late, enjoyed the returns they might have expected. Greg Pearson attributes this to three obstacles; the fact that Vanteck did not originally control all the rights to the technology which it now does; the absence of a US-situs application which the PacifiCorp order resolves; and the perceived limitation of being quoted only on the CDNX market. Vanteck shares can now be traded on the Frankfurt market but it is the intention to ultimately obtain a London listing.

A protracted reverse takeover of parent company, Pinnacle, led to a collapse of investor confidence and saw Vanteck’s share price dip to as low as 62 cents, from a high of 265 cents.

New goals

Despite the innovative nature of its product, Vanteck has failed to engage investors and exploit the business opportunities that the VRB VESS offers. Earlier this year, it took dramatic steps to address this when it announced wholesale changes to its upper management. Chairman, Rodney Duncan, stood down and was replaced by Peter Stedwell (Chairman of Federation Group, which owns 47 per cent of Vanteck). Experienced project engineer Don Nicholson was appointed CEO and will oversee the buildout, installation and commissioning of the PacifiCorp project and a new Finance director, Gavin Cooper, was also appointed.

The changes, which took effect from the beginning of April, are intended to lead to significant new partnerships and growth for Vanteck. A new investment banking group has been established within the company and the new management team has set its sights on the European market as having the greatest potential for the technology, when linked to renewable energy projects. “Our emphasis is towards establishing partnerships particularly in the field of renewable energy,” said Nicholson. “We are hoping to announce a wind related venture in Europe within the next three months,” he added.

The management upheaval has already led to an important partnership arrangement being put in place. Vanteck’s Pinnacle subsidiary was able to announce a deal with Sumitomo Electric Industries which secures the supply of VRB cell stacks and makes it the principle supplier of VRB/VESS systems to commercial customers worldwide.

The quest has not been a smooth one, but time will tell whether Vanteck has in its grasp the energy storage equivalent to the Holy Grail. Certainly the performance of the PacifiCorp VRB/VESS system will be followed closely by those in the power supply industry. They will need to be convinced that VRB/VESS is the technology to meet the increasing demand for uninterrupted back-up power for ride-through, peak shaving, reliable and quality power.

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