Small hydro |
Left: VETT control cabinet, Eaton Socon, UK Below: VETT-in-Box, closed Bottom: VETT-in-a-Box, open, with turbine and conical fish screen
j With adequate fish screening of the small turbine flow, VETT technology as a whole is fish safe with proven zero fish mortality. This has been proven in live fish trials verified by the Environmental Agency (England). Impact research encompassing ecology surveys, geomorphological studies, flood risk assessments and live fish impacts tests show VETT is inherently environmentally friendly. Other technologies leave significant doubt regarding their fish damage and mortality rates, or become unviable if the entire flow requires fish screening.
Next stage of development Detailed design engineering on VETT-in-a-Box has
begun, with the product expected to be available worldwide within 2022. Improvements to the Standard VETT, which is already available, have also been identified following learnings from Eaton Socon, working in parallel with VETT-in-a-Box development. These lessons learnt will be fed into any new projects going forward.
VETT-in-a-Box, patented by VerdErg in over 20 countries, is a product for the global market and the wider VETT technology has true global potential. Most regions of the world possess hundreds if not thousands of projects which require a smart approach to low-head hydropower. VerdErg has identified 9 GW or a £10bn market remaining within rivers alone. Besides the home market of the UK, VerdErg’s
current international focus for VETT technology is Brazil, where there is a favourable licensing and payment regime for the mini and micro sector, especially for projects under 75kW. The Brazilian government is offering incentives to develop smaller, decentralised projects for local supply and is turning away from large hydro plants. Focus is also placed on the USA, which has 80,000 smaller unpowered dams and a strong appetite for renewable energy with 100% clean energy legislations introduced in several states. In Europe, France has also been identified as one of the first target markets, being a leader in hydropower. Over time, the company intends to expand internationally and there are very few geographical limits for the application. We envision an exciting future for VETT-in-a-Box and VETT in general and look forward to seeing positive change in the run-of-river hydropower industry from this technological innovation. VerdErg has so far received interest from traditional small-scale hydropower customers such as private landowners and community groups, as well as government agencies, NGO research bodies with stations in very remote regions as well as the military. First partnerships have been struck, leading to the build up of a pipeline of projects. VerdErg is also actively looking to raise investment to expand the team and increase the regions where VETT technology is marketed. ●
VETT in operation
The first VETT installation is a 26kW installed capacity scheme commissioned in 2019 on the river Great Ouse in Eaton Socon, Cambridgeshire, exploiting the 1.2m net head between a marina and mill pond. The VETT is submerged within a disused underground culvert, integrated into the existing infrastructure of a Grade-II listed former mill, now restaurant. Generated electricity supplies the restaurant with excess exported to the National Grid. The installation has a design flow of 3.5m³/sec. The intake tank is fed by one of the three existing culverts with the entire tank situated below ground level. A new intake structure was constructed within the marina to feed the culvert. All infrastructure is submerged underwater, with zero noise or visual pollution caused. The VETT pipe draws flow from within the intake tank and
amplifies the pressure across the turbine. The turbine is designed with a fixed blade 440mm diameter runner. The nominal speed of the turbine is 750rpm which is designed to operate at variable speed to ensure the system operates at peak efficiency. There is no regulation of the runner or the guide vanes. If the turbine were dynamically scaled to operate without VETT, i.e., with only 1.2m head and the full design flow, the runner diameter would increase from 440mm to 1,230mm. and the speed would reduce from 750rpm to 174rpm. A turbine operating without VETT would require a gearbox and deeper excavations. The VETT pipework is hung from a galvanized steel frame. It was positioned fully assembled via a single crane lift onto the frame, a successful installation procedure negating requirements for any large cofferdam in future installations.
20 | April 2022 |
www.waterpowermagazine.com
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