Environmental considerations for Kinetic Energy versus battery back- up for large scale UPS applications
Across every manufacturing sector the definition of cost has changed.
True cost now includes full environmental impact calculations. This spans the cost of extracting and transporting raw materials, the carbon footprint of production processes, whole of life operation and disposal.
Nowhere is this truer than in the energy infrastructure sector. In terms of sustainability and environmental impact power infrastructure is under the microscope.
Active Power flywheel technology has been created as a highly reliable, energy-efficient, battery-free UPS (Uninterruptible Power Supply) system. Known as CleanSource UPS the range creates a predictable, continuous power system that will ride through power outages to keep critical operations up and running.
A description of how CleanSource operates to provide clean, efficient, sustainable power protection can be found below but for now let’s examine the environmental credentials of kinetic flywheel versus battery back-up.
CleanSource UPS is a strong fit for sustainably/environmentally conscious specifications for three main reasons:
It contributes to a safe, healthy environment. Because of its energy efficiency, customers draw less power thus helping to reduce CO2 emissions. CleanSource is up to 98% energy efficient.
Kinetic does not produce toxins or other emissions.
The CleanSource UPS is comprised of benign metal components such as copper, steel and aluminum and therefore can be recycled, often for credit, at any local scrap facility.
It delivers consistent, predictable performance over its 20-year life span with absolutely no degradation in service. As a result, operators can avoid the recurring cost and risk of removing and disposing of lead-acid and li-ion batteries every three years due to their limited life cycle.
Batteries
Lithium-ion battery power technology has changed the world and there are many applications for which it is perfectly suited. However, for long term UPS power back up for industrial scale applications it comes with significant challenges and drawbacks.
By taking account of extraction, the raw materials involved, manufacture, operation, replacement and finally disposal paints a true picture of the environmental cost of battery back-up.
Extracting lithium is resource intensive. It is estimated that the lithium extraction process uses approximately 500,000 gallons per metric ton of lithium.
At the manufacturing stage battery-based UPS systems typically use flooded cell batteries, which contain sulfuric acid electrolyte, VRLA (valve regulated lead acid) batteries or lithium. They contain many toxic and hazardous materials meaning flooded cell, VRLA and lithium batteries present safety and disposal issues.
When operational VRLA batteries have a shorter life expectancy, requiring frequent replacement. The numbers of batteries that will need to be accounted for is growing rapidly. For example, one large company based in India has 30,000 lithium ion batteries installed for power back up across its various sites. It replaces over 4,000 batteries every year.
At end of life there is currently no standard process for recycling lithium ion batteries, even for consumer goods. And there is certainly no proven, safe long term disposal method for large numbers and large batteries.
With no proven safe disposal process of batteries or its chemicals then long-term storage of spent batteries must be considered. But even here the challenges are significant.
There is no standard method for long term storage. There is already an explosion in the number of startup companies working on clean disposal, extending the usable life and reuse of batteries and looking for long term storage options. But neither a disposal solution breakthrough nor viable, safe, low cost long term storage method is as yet on the horizon.
Disposing of used batteries by dropping them into an active volcano has been suggested!
It does not seem far-fetched to suggest that environmental regulators will take more interest in battery use and disposal by industrial users of lithium ion and VRLA batteries. As accurate environmental cost metrics emerge operators at scale could face significant additional costs for disposal or long term storage at end of life – or face very stiff penalties.
How Cleansource UPS delivers clean, sustainable energy
Cleansource is field proven in a variety of applications including data centers, hospitals, airports, oil/gas refineries, broadcast outlets and military installations, to name a few.
A flywheel energy system stores kinetic energy by constantly spinning a compact rotor in a low-friction environment.
Active Power’s UPS systems are similar in this respect. CleanSource is unique in that it uses an integrated flywheel approach combining the functions of a motor, flywheel rotor and generator into a unified system. The motor, which uses electric current from the utility grid to provide energy to rotate the flywheel, spins constantly to maintain a ready source of kinetic energy. The rotor spins in a near frictionless environment, developed by Active Power’s patented magnetic bearing technology. This innovative technology unloads a majority of the flywheel’s weight from the field-replaceable mechanical bearing cartridge. The efficiency in the chamber is further enhanced by the creation of a rough vacuum, which reduces drag on the spinning flywheel.
The technology uses a parallel, on line design that makes the UPS systems much more efficient than conventional, double-conversion battery-based UPS systems. The on line interactive design innovation allows a reduction in UPS system efficiency loss and with an integrated flywheel energy storage component, the flywheel can achieve efficiencies of 98% compared to 96% for conventional battery-based UPS systems. In the 1,000 kVA size range, the difference can easily amount to an annual energy savings of $10K-$15K if the energy rate is $.07 per kWh.
When a power disturbance occurs, the generator converts the flywheel’s kinetic energy into electricity providing short-term back-up power as the rotor’s inertia allows it to continue spinning. As power is transferred to the load, the flywheel’s speed decreases. Additional current is then supplied to the field coil to ensure the voltage output remains constant throughout discharge. This enables the flywheel system to provide ride-through power during power disturbances. CleanSource provides ride-through power for the majority of power disturbances, such as voltage sags and surges, and bridges the gap between a power outage and the time required to switch to generator power.