Handbook of Energy Storage for Transmission or ... - W2agz.com

EPRI Proprietary Licensed Material
Regenesys Electricity Storage Technology
• Space requirements: Innogy says that a 100MWh/10MW plant will occupy 1 hectare (2.5
acres) or less. This corresponds to a footprint of slightly less than 1kWh/ft 2 , or not too
dissimilar to the total site area for single-story plant based on flooded lead-acid cells.
• Efficiency: Innogy estimates that the round-trip energy efficiency (AC energy out versus AC
energy in) of early Regenesys plants will be 60-65%. Higher than the nominal rates of
discharge (15MW versus 10MW nominal) are expected to be sustainable for up to a quarter
of the normal 10-hour discharge time, but such higher rates of discharge will reduce the
AC-AC efficiency to 50-55%.
• Life: According to Innogy publications (see Bibliography and www.regenesys.com) a plant
lifetime of 15 years is being planned for. Since there is already considerable experience with
the membranes (the expected life-limiting component) under much harsher conditions, a 15-
year life expectation does not appear unwarranted.
• Maintenance Requirements: Within the fifteen year life expected for the plant, Innogy
projects that 3-month inspections will be necessary, and that occasional repairs of some of
the mechanical components (pumps, valves, etc.) might be needed. Moreover, the crystalline
sodium sulfate that is the end product of inefficiency of the membranes (see above) will have
to be collected every two weeks, trucked away, and sold or disposed of away from the site.
Sodium sulfate is regarded as an environmentally benign material of low toxicity. It is
produced in million-ton per year quantities in the US, with half the production being as byproduct.
Sales of the material lagged production by almost 50% in 1999. Sodium sulfate
sells for, very approximately, $100/ton.
• Likely Environmental Impact, Safety Considerations: Regenesys plants have been designed
and configured (see Figure 5) in such a way as to minimize any environmental impact and so
as to ensure the safety of personnel visiting the plant and that of people living nearby. An
Environmental Impact Assessment (see Bibliography) has been prepared which indicates that
a Regenesys plant will be environmentally benign.
• Auxiliary Equipment Needs: Innogy is using a system approach to design of their Regenesys
energy storage plants, and has even formed an alliance with ABB (see next section for further
discussion) for provision of AC-DC-AC converters for their systems. Innogy indicates that
no auxiliary equipment other than that provided by itself or its vendors will be needed for
Regenesys plants.
• Power Converter Needs: No information is available on this since Innogy and ABB regard
this as proprietary information. In any case, the developers regard the power converter as an
integral part of the Regenesys energy storage plant. By comparison with other PCS units of
similar capability, it is estimated that the efficiency of an ABB converter will be
approximately 95% round trip
The performance characteristics, at a “black box” functional level, of a Regenesys plant are
expected to be as follows:
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