C-GEN is an innovative multi-stage air-cored PMG technology that is applicable to direct drive, slow or medium speed generator designs for wind, tidal and wave energy converters.
C-GEN generator technology has the following USPs over existing generator technologies used for direct drive:
- No Magnetic Attraction Forces closing the airgap - this simplifies the support structure required, and makes assembly of the stator and rotor modules easier.
- No cogging torque - more of the input mechanical energy will be converted to electrical energy, and noise and vibration will be reduced.
- High Degree of Modularity - the use of air-cored coils allows a high degree of modularity in both the stator and rotor construction.
- Higher availability - Due to the high degree of modularity, C-GEN can be reconfigured to isolate faults whilst still operating, and modules can be replaced relatively easily reducing downtime.
- Reduced CAPEX & OPEX - The high degree of modularity enables volume production using standard components, keeping CAPEX low. Modularity enables replacement of single faulty modules rather than the complete machine increasing the turnaround of any O&M procedures, enabling low OPEX costs.
- Reduce LCoE - with the higher availability, lower CAPEX and OPEX costs and equivalent performance, C-GEN generators contribute to lower LCoE.
C-GEN History
C-GEN was developed in 2005 by Prof Markus Mueller in the School of Engineering within the Institute for Energy Systems at the University of Edinburgh. With Scottish Enterprise funding under the Proof of Concept Programme, C-GEN was demonstrated at laboratory level through the design and build of two prototype:
- 20 kW at 100 rpm, tested in the laboratory at Edinburgh
- 15 kW at 150 rpm, installed on a 15 kW Proven Wind Turbine
Successful demonstration of these two prototypes was used to prove the concept, verify design tools, component manufacturing and final assembly procedures. Both prototypes were built by Fountain Design Ltd. who have been involved with the C-GEN development to the present day. On the back of these two prototypes, Prof Mueller founded in 2009 a spin out company, NGenTec, with colleague Dr. Alasdair McDonald. NGenTec raised investment through venture capital and public funding to scale C-GEN from the laboratory to multi-MW scale. Two additional prototypes were built within NGenTec:
- 25 kW at 100 rpm, multi-stage axial flux machine tested in the laboratory at Edinburgh
- 1 MW at 13 rpm, multi-stage axial flux machine tested at David Brown Gears in Huddersfield
These two prototypes further demonstrated the technology and led towards industrialisation of the generator. Component manufacturing techniques were developed that could be replicated within a manufacturing environment. Design tools were further verified providing confidence that C-GEN could be designed for any rating of a wind turbine. Unfortunately the company ceased to trade in 2013, but all the Intellectual Property was passed back to the University of Edinburgh for further exploitation.
As well as wind energy, C-GEN design studies were conducted for tidal and wave energy applications with nPower juice funding. Reports from this work can be found elsewhere on the website. In order to explore C-GEN for wave energy funding was obtained under the Carbon Trust Marine Accelerator Programme in .2008. A 50 kW, 1m/s linear generator was designed, built and tested, and with based on the results further funding was obtained from Wave Energy Scotland in 2015 as part of its Novel PTO call to focus on critical components, the windings and bearings. In May 2017 the Edinburgh team were awarded a Stage 3 Wave Energy Scotland project, C-GEN Project Neptune, to demonstrate the generator technology at scale, in this case 150 kW, in the real marine environment. Project Neptune is set to run until May 2019, and is the current main project to develop C-GEN for the wave energy sector, but all learning can be applied to other sectors, such as tidal and wind.
Search the site for more detailed information on the various C-GEN prototypes and projects.
