THE FUTURE OF ENERGY STORAGE WITH MAG DRIVE PUMPS AT ITS HEART
28th Aug 2015
Vanadium redox batteries are one of the most promising energy storage solutions and centrifugal pumps are at their heart.
Centrifugal pumps are the unsung heroes of most everyday processes. On average, the average person will experience a process that has been powered by a centrifugal pump 8 times a day. It is the same story for the new and developing vanadium redox battery technology being developed by companies across the globe. These companies are looking to create a world able to produce renewable energy via wind, solar, or tidal power and then store the generated energy with vanadium redox batteries for later use or transportation.
There are many possibilities associated with vanadium redox batteries, making them well suited for use in larger power storage applications, such as helping average out the output of highly variable generation sources like wind or solar power, helping generators cope with surges in demand at peak times, or levelling out supply and demand at transmission-constrained regions.
Vanadium flow batteries are one of the few new battery formats that hold the promise to be capable of affordably storing energy for prolonged periods of time. That’s a valuable feature for grid-scale energy storage that tackles the problem of providing energy and electricity to remote areas.
Energy Storage – Advantages
The main advantages of vanadium redox batteries are their ability to offer almost unlimited capacity simply by using larger storage tanks and that they can be left completely discharged for long periods of time with no ill effects. Then can be recharged simply by replacing the electrolyte if no power source is available. Better yet, if the electrolytes are accidentally mixed, the battery suffers no permanent damage.
Vanadium redox batteries have the power to change the way the world produces energy. By combining these batteries with solar or wind power while matching the cost of existing energy generation from gas, coal, and nuclear power, the vanadium redox batteries could become the most sought-after and desirable means of energy production. The market for vanadium flow batteries is forecast to be worth $390 million (€357 million) by 2020, according to Lux Research.
The centrifugal role
Vanadium redox batteries work like a rechargeable fuel cell. The charging process involves power cells in which two electrolytes are separated by a proton exchange membrane. Both electrolytes are vanadium-based, with the electrolyte in the positive half-cells containing + ions and the electrolyte in the negative half-cells containing – ions. This vanadium-based chemical remains extremely acidic throughout its use. Both half cells are additionally connected to storage tanks and centrifugal pumps so that very large volumes of electrolytes can be circulated through the cell.
The vanadium redox battery technology is solely reliant on centrifugal pumps for processing the acid liquid from the storage tank to the electrode membrane to convert chemical energy to electrical energy or vice versa.
Diagram of the vanadium flow setup
It is essential that the centrifugal pump is selected correctly to combat the corrosive and acidic properties of the vanadium solution whilst maintaining over 70% average operating efficiency. For this type of acid, we have found that pumps built with thermoplastic work best, ensuring a long working life for the pump.
For the most optimal process, it is best to utilise dry-run protection installed in a select range of magnetic drive pumps, which enable the system to run dry up to 8 hours without damaging equipment. This feature ensures a leak-free and safe working environment, which is particularly important when processing highly valuable and volatile media such as vanadium solution.
These features combined prolong the life of the pump and safeguard the process from any maintenance or downtime which is paramount to grid-scale systems. Most flow battery systems can involve up to a 100 pumps in one facility, which may result in a massive burden for maintenance personnel. With magnetic drive pumps, maintenance is reduced to the bare minimum (practically non-existent) due to the way the magnetic drive ranges have been designed.
The vanadium redox battery system is designed to utilise and store as much energy as possible, and the pumps must conform to that. That is why it is critical to utilize a high efficiency IE3 motor, in line with new EU regulation as of the 1st of January, 2015.
CASE STUDY
Most recently Crest Pumps worked with Vanadis Power to provide 16 magnetic drive pumps for construction of a fuel cell battery system to harvest energy generated from a wind park located near Flensburg, Germany.
These magnetic drive pumps were part of the biggest battery storage system in Germany in a joint venture with Bosch, and the project was one of the largest in the world using vanadium redox flow technology. The storage would theoretically be able to provide electricity consumption for a 100 family houses on a single charge.
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To confirm to the technical and engineering efficiency requirements for the battery installation the pumps needed to:
- Be magnetically driven to ensure the highly volatile media remained inside the process at all time to avoid costly leakages and clean up bills
- Include built-in corrosion resistant materials to ensure the pumps continued to have a long service life pumping the highly acidic vanadium solution.
- Maintain an overall 74% processing efficiency in line with battery efficiency specification.
- Use highly efficient IE3 motors to ensure maximum cost savings over a 10 year lifespan.
Crest Pumps supplied the magnetic drive AMX range as its most suitable chemical pumping solution to Vanadis Power’s requirements. The pumps were dispatched and delivered within two weeks of the original enquiry.
Crest Pumps AMX pump supplied to Vanadis
Crest has also been awarded contracts with another two of the ‘Big 5’ of flow battery companies to provide hundreds of pumps for solar installations across the globe. The pumps supplied to these companies are also in the magnetic drive AMX and AMA ranges providing a long working life with minimal maintenance. These pumps also feature the run-dry protection that can provide much needed emergency response time to address a problem without the process faltering as a result.
View to the future
Vanadium redox batteries have the potential to change the way the world generates power. Distant communities and areas or temporary refugee centres, for example, can suddenly be supplied with energy with the help of these batteries.
Much of the debate over the long-term usefulness of battery technology in the US and UK is focused on whether or not batteries can be combined with solar and wind power while still matching the cost of our existing natural gas, coal, and nuclear plants, which at the moment are producing energy at their cheapest possible prices.
However, in Africa or Indonesia import costs are high, infrastructure limited, and natural deposits of fossil fuels are low. Africa also has enormous renewable energy potential: it receives huge amounts of solar power, its hydropower generating capability is largely untapped, and its geothermal and wave power are both abundant.
Vanadium flow batteries could potentially augment renewable power in many areas across the continent boosting economic growth and development with centrifugal pumps at the heart of the process.
