IDTechEx technology analyst Harry Zervos recently interviewed Dr Markys Cain, from the National Physical Laboratory (NPL) in the UK. The NPL is involved in the European Metrology Research Program (EMRP), supported by funds from the E.U. framework 7 programme and from EURAMET (European Association of National Metrology Institutes). The EMRP will ensure collaboration between National Measurement Institutes, reducing duplication and increasing impact with the overall goal of the EMRP to accelerate innovation and competitiveness in Europe.
As part of the EMRP, and due to Europe's particularly strong position in the field of energy harvesting, an initiative started approximately 6 months ago; the Metrology for Energy Harvesting project which is focused on measurements of materials used in energy harvesting (EH) applications. The goal is to establish their relevant characteristics using standardised testing (e.g. Specific tests, equipment, specimens, conditions), which will assure comparability of results. Due to the large variety of EH technologies and ambient energy sources, the initial focus is on thermoelectric and vibration harvesting.
What becomes clear when closely inspecting EH solutions is how application specific they are: Harvested energy and power, would it be needed constantly or intermittently What kind of load is the harvester attached to Is it for example, a capacitive, electromagnetic or resistive one How does the load affect the harvesters themselves
"All these questions highlight the need for a metrology standard" says Dr Cain "as it would offer the possibility of calculating a figure of merit, measured by a national measurement institute, giving reassurance on what quoted devices characteristics really represent."
The quality of energy harvested is also of great importance: In the case of vibration harvesting for instance, until better understanding of non-linear properties and application of these properties in broadband harvesting is achieved, vibration harvesting happens almost in its entirety at a single resonant frequency and energy gathered falls dramatically as one moves away from it. Similarly, specific material systems are to be used for given temperature ranges and differentials in the case of thermoelectrics. This highlights the need to understand input energy and the transfer properties to the harvester and subsequently to the load through the electronics of the overall device, leading to an overall effect in the final efficacy of the system that needs to be better understood in order to be optimised.
The project will be the means to achieve accurate efficacy measurements of the relevant technologies in order to understand quoted performance data in terms of input energy and power, power output, etc. Training sessions, seminars and workshops will raise awareness and will take into consideration suggestions and input from end users and developers of EH technologies in order to create standards that will cover all necessary issues.
Burkhard Habbe, VP of business development at Micropelt GmbH, also voiced his support for the initiative. Talking to Dr Zervos, Burkhard said: "Ten harvesters with different data sheets quoting different parameters measured under a variety of conditions are not comparable. This project is helping metrology fill the gap of standardization, taking into account perspectives from manufacturers, integrators as well as end-users, by defining measurement conditions and qualifying systems and harvesting environments."
Burkhard continued to say that quite often manufacturers and their clients end up with proprietary, private solutions that sometimes impede further understanding and adoption of emerging technologies. "Certification will put the consumer's mind at ease leading to a growing market which, in 5-10 years from now will have moved away from small, private solutions."
