Yorkshire Water gets good vibes from microgenerator

Perpetuum has developed the first effective vibration energy harvesting microgenerator that makes wireless, battery-free sensors a reality. Yorkshire Water, along with the US Navy and a major international oil company, has been trialling the PMG7 high-performance microgenerator. We take an in-depth look at the technology and how it has been benefiting the water utility.

When it comes to research and development (R&D), Yorkshire Water is no novice

– which could explain why it has evolved from being seen as one of the most inefficient companies about ten years ago into being one of the most efficient.

Over the years, the company has been involved with more than 400 R&D projects, and worked with at least 60 university departments.

And, says Martin Tillotson, head of R&D at Yorkshire Water, the search for new

and better technology is ongoing. IT and telemetry, for instance, accounts for 6% of the company’s 2006/07 R&D programme.

Tillotson explains: “Yorkshire Water is reforming telemetry at present. We are looking at developing new technologies, and re-engineering existing technologies. Our aim is to increase the visibility of our asset base. We don’t have a good understanding of what happens at facilities.”

At the end of the day, Yorkshire Water wants to achieve a “predictive response” to maintenance.

No surprise

So it comes as no surprise that the water utility is involved with field trials concerning Perpetuum’s vibration energy harvesting technology, and which involves using wireless and battery-free devices capable of sending large amounts of data from many types of industrial equipment.

Perpetuum, a spin-out company from the University of Southampton and founded in 2004, specialises in self-powered sensor systems eliminating the need for external wires or batteries. It has developed the PMG7, a high-performance microgenerator that can power sensors, microprocessors and transmitters for accurately monitoring the condition of plant equipment and machinery, without the need for batteries, expensive cabling or maintenance.

The easy-to-install solution is now available to OEMs, sensor manufacturers and end-users in all industries, allowing them to make significant cost savings.

The microgenerator converts kinetic energy from the equipment’s vibration running at mains frequency – 50 or 60Hz – into electrical energy. It can generate up to 5MW, enough to power a wireless transmitter sending up to 6kilobytes of critical data every few minutes, or smaller amounts of data – such as a temperature reading – several times a second.

The PMG7 series of vibration energy harvesting microgenerators are energy sources for low-power electronic systems such as wireless sensor nodes. In a typical application, power derived from vibration is delivered as a charging current directly to an external storage capacitor.

Once sufficient charge has been accumulated in the capacitor, application circuitry is enabled and performs its required function. Power for all work cycle functions is provided as the capacitor discharges. The PMG7 series devices require no extra circuitry in order to charge a capacitor directly to 3.3V.

The resonance of the PMG7 series of energy harvesters allows them to derive the maximum power from the targeted frequency operating bands, which are listed in the following table. However, the centre of the operating bandwidths may be manually tuned during installation in order to maximise power generation.

It is a practical device that can operate in most industrial environments and at minimal vibration levels (25mg).

The easy-to-install microgenerator simply screws into place, or can be held in place by magnets. It is then left in place with no need for maintenance.

Following the recent £2.2M new funding round developments are under way to extend the range of applications and the performance of these devices.

Perpetuum CEO Roy Freeland says the microgenerator is an enabling technology designed to convert waste energy into electricity. “It’s harvesting barely perceptible vibrations.”

He says that there are “enormous benefits to using this – being able to install this without interfering with existing equipment at a process plant”.

Cost savings

The PMG7 allows operators to continually monitor plant equipment, providing valuable data – such as temperature and vibration – about the condition of equipment including pumps, motors and fans. The data can be used to optimise the efficiency and availability of plant, increase the cost efficiency of maintenance work, to prevent accidents and make significant savings in energy costs.

According to the ARC advisory group, this is a market that can expect significant growth in the next three years, reaching almost £700M by the end of next year.

In addition to Yorkshire Water, Perpetuum has also completed field trials with the US Navy and an international oil company. Freeland says: “This is a practical device, not a laboratory experiment. No competitive offering has come close to this level of performance in terms of the amount of data that can be sent, or the conditions under which it will operate reliably.”

The trials have been completed using the S5NAPTM remote sensing module from Perpetuum’s US partner, RLW, which develops high-quality innovative hardware and software for Condition Based Maintenance (CBM) applications. Its devices perform machine health monitoring and provide health status messages to remote destinations. RLW developed the S5NAPTM to exploit vibration energy harvesting after selecting Perpetuum’s microgenerator as the best alternative by far.

Yorkshire Water is using six S5NAPTM modules to report the health of pumping equipment and blowers at its Esholt plant. The modules are providing vibration spectra and temperature data for condition monitoring.

Stephen Roberts, technical manager at Perpetuum, says the temperature data has been transmitted every 30 seconds while the overall velocity has been every 30 minutes. “If a monitor goes very high, it can alert the operator that something is wrong and the motor can be shut down.” The S5NAPTM module, says Roberts, spends a lot of its time asleep. “It comes alive to transmit data, then goes back to sleep.”

The other two trials entailed:

  • A S5NAPTM module being installed on a compressor at the US Navy’s Philadelphia base to show the transmission of vibration and temperature data
  • Three S5NAPTM modules were supplied for a trial installation on a test pumping circuit at a major oil company. These were mounted with magnets onto pumps motors and pipework to produce data for condition monitoring

Benefits include

  • Reduced costs
  • Faster and easier installation
  • The devices can be used anywhere
  • High reliability, with no wiring failures or battery failure

Peter Boruszenko, senior R&D engineer at Yorkshire Water, explains Yorkshire Water’s interest in the technology. He says that the company has been looking at condition-based monitoring for some time because of the rising E&M and energy costs.

He says that, on average, pump repairs have cost about £1.2M a year. “And it’s not just about cost, there are environmental issues too.”

Repairing a pump can cost £100,000 to £200,000, while a replacement quote can be as high as £100,000.

Yorkshire Water was seeking a low-cost solution comprising simple installation, no mains power, no hard-wired communications and a simple set-up.

The trial objectives for Yorkshire Water included:

  • Detecting blockages and cavitation
  • Confirm problem detection
  • Determine where the devices were best employed
  • See whether deployment could lead to maintenance changes

Boruszenko says: “We could have used a whole range of technologies but these didn’t really meet our criteria.” It opted to use Perpetuum’s offering instead because of its “huge potential”.

However, Yorkshire Water is not turning its back on hard-wired solutions. Boruszenko explains: “We are rolling our hard-wiring systems but only where the application warrants it.” It costs about £1,500 for a hard-wiring solution – three times that of the Perpetuum offering – and the battery systems incur huge maintenance costs.

The Perpetuum solution has been trialled on air compressors, fan motors and sludge pumps. “The more we can get these devices on blowers, the better,” says Boruszenko. The water utility is measuring the trial’s success through detecting problems before a catastrophic failure occurs. “It will be a very powerful tool for Yorkshire Water.” Boruszenko concludes.

Condition monitoring explained

Vibration energy harvesting is where the vibration of a piece of plant or machinery is transformed into an electrical signal, and is a highly attractive option for wireless condition monitoring because all mains-driven machinery vibrates.

In fact the level of its vibration is frequently used as an indicator of its condition. Continuous monitoring of plant and machinery provides valuable data about the performance and condition of that equipment. The data can be used to optimise the operation and availability of plant, improve cost-efficiency of maintenance work, prevent accidents and make significant savings in energy costs.

Despite its benefits, continuous condition monitoring is currently carried out on only a small percentage of installed industrial machinery worldwide because of the limitations and cost of the existing wired and battery-powered technologies.

Wired systems are too expensive to install on a widespread basis, and wireless, battery-powered systems suffer from reliability and maintenance issues. There are limited instances where equipment is located outside in sunny regions, and if measurements are not required at night, solar power may be viable.

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