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Low-Head Hydropower Innovation: Harnessing Hydroelectric Power from Low-Head Sites

July 13, 2022
Booth #1802, Exhibit Floor
Knowledge Hub - Technology Horizons
IRENA estimates that to meet the forecast 50% increase in global energy demand by 2050, and to do so within required reduced carbon emission limitations, hydropower capacity will need to increase by 25% before year 2030 and 60% by 2050. Approximately 850 GW of newly installed hydropower capacity will be required in the next 30 years, roughly equal to adding the entire power system capacity of the European Union in 2020. In addition to new capacity, IRENA estimates more than 600 GW of the current aging hydropower fleet will require refurbishment and modernisation (IRENA, Global Renewables Outlook, 2020). This high forecast demand is seeing renewed interest in hydropower as a low carbon source of electric power. Pumped hydro is considered a valuable stable base load for wind and solar, sectors with governmental support and investor attention, and small run-of-river hydro is key for decentralised electricity production and intelligent development within existing watercourses. To meet this potential, innovation in small, low-head hydropower technology is necessary, as well as a greater focus on sustainability and biodiversity factors to meet the needs of public, investor and regulation approvals. Innovation is vital because typically, low-head hydropower does not create enough power to make the installation worthwhile from a cost perspective. With decreasing governmental support, most installations are not economically viable and LCOE is not competitive with wind or solar. 11 GW of low-head hydropower potential therefore remains untapped due to cost-inefficient turbine solutions for such low-pressure settings. In addition, many man-made watercourses such as waste water outfalls and distribution infrastructure remain under-utilised (IEA Hydro). This paper presents a case study of a novel low-cost hydropower technology for low-head applications called Venturi-Enhanced Turbine Technology (VETT). Findings and lessons learnt will be presented and discussed from the first UK VETT project operating since 2019 and installed in an unused culvert. VETT units are suitable for run-of-river sites with installed capacities from 20 to 130kW, and available head drops of up to four metres. It can also be installed into any low-pressure watercourse such as waste water outfalls or water treatment plants, unharnessed water flows with significant potential as recognised by the IEA’s ‘Hidden Hydro’ research project. A further aspiration is to use the technology in tidal settings. VETT technology acts as a pressure amplification system that changes the operating conditions so that turbines designed for higher head projects can be utilised in low-head projects. Instead of providing the turbine with a large volume of water at low pressure, VETT uses one part of the water in a venturi to achieve a pressure amplification, therefore providing the turbine with a profile of less water volume but at a higher pressure. This increases the head the turbine experiences by ca. 2.5x. As a result the turbines can be 3-5x smaller and up to 15x faster, and a gearbox is not required. Fish screening is 5x smaller than conventional technologies as only 20% of water through a VETT encounters moving parts. The fish-friendly and sustainable VETT is verified ‘low-risk’ with proven zero fish mortality and zero noise or visual pollution keeps impact on local eco-systems minimal. This innovative, compact technology is therefore suitable for a variety of potential installation sites and is significantly more affordable than traditional technology, with 45% less investment costs than typical low-head technologies. Cost of energy and project returns for low-head hydro projects are improved, with shorter payback periods and higher returns.

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