The importance of pico hydropower generation

Electricity is critical for improving health, creating jobs, and allowing time for families to generate an income instead of spending a disproportionate time on domestic tasks. According to the International Energy Agency, there are over 1.3 billion people who do not have access to electricity, with almost 1 billion of these living in rural locations where households are dispersed across the landscape, and often the areas are in remote, inhospitable and mountainous terrain. The cost of providing electricity from a centralised grid to these households is high, and so off-grid solutions are attractive.

There are several different sources for off-grid electricity supplies, such as diesel generators, solar photovoltaics, wind turbines, biomass generators and hydro turbines.

Pico-hydropower, electricity generation under 5kW, can be used where there is a stream or river flowing near to a community. Several countries, such as Nepal, Vietnam, Laos and Peru, have been exploiting pico-hydropower for the past few decades as a way to provide electricity to rural locations. A locally made pico-hydro turbine is shown in Figure 2.

Typically pico hydro systems have been stand-alone, with only a single house or a small group of houses connected to a single turbine. Large loads cannot be driven as there is not enough capacity in the system. If the unit fails then all the consumers for the turbine must go without power. Sometimes, there may be multiple sites for turbines around a community, often with a different turbine design at each site. However, these can still only feed a small number of houses each, as illustrated in Figure 3, as there is no standard way of connecting the units together.

If all of these turbines were able to be joined together electrically to form a network, as illustrated in Figure 4, with identical turbines at each site, then this would allow for larger loads to be driven, with good redundancy, and it would allow for spare parts to be held.

Research at Bristol

At Bristol, we have been developing and running scaled tests of a turbine design that can be used at low-head sites for a variety of environmental conditions. This can be made in rural workshops with a minimal amount of tooling. A picture of this turbine being tested can be seen in Figure 5. We are currently constructing a full scale version of this turbine.

We have also been investigating a power electronic interface to connect each turbine onto the off-grid network, to ensure that power is shared and the network voltage and frequency are controlled.

For more information please see the following publications:

S. J. Williamson, B. H. Stark, J. D. Booker, “Site Implementation of a Low-Head Pico-Hydro Turgo Turbine”, in World Renewable Energy Congress, Kingston, UK, 2014.

S. J. Williamson, A. Griffo, B. H. Stark and J. D. Booker, “Control of Parallel Single-Phase Inverters in a Low-Head Pico-Hydro Off-Grid Network,” in Annual Conference of IEEE Industrial Electronics Society, Vienna, 2013 pp 1571-1576.

S. J. Williamson, B. H. Stark and J. D. Booker, “Performance of a low-head pico-hydro Turgo turbine,” Applied Energy, vol. 102, pp. 1114-1126, 2013. 

S. J. Williamson, B. H. Stark and J. D. Booker, “Low head pico hydro turbine selection using a multi-criteria analysis,” Renewable Energy, vol. 61, pp. 43-50, 2014.

S. J. Williamson, B. H. Stark and J. D. Booker, “Modelling of a Multi-Source Low-Head Pico Hydropower Off-Grid Network,” in IEEE International Conference on Sustainable Energy Technologies, Kathmandu, 2012, pp. 369-374.

S. J. Williamson, B. H. Stark and J. D. Booker, “Experimental Optimisation of a Low-Head Pico Hydro Turgo Turbine,” in IEEE International Conference on Sustainable Energy Technologies, Kathmandu, 2012, pp. 322-327.

S. J. Williamson, B. H. Stark and J. D. Booker, “Low Head Pico Hydro Turbine Selection using a Multi-Criteria Analysis,” in World Renewable Energy Congress, Linköping, 2011, pp. 1377-1385.

Pico-Hydropower Workshop

In conjunction with EWB-UK and the Small is… Festival, we have devised a workshop where the participants build and test a pico-hydro turbine. The workshop was used at the Small is… festivals in 2012 and 2014, and is regularily used in primary and secondary schools, on Headstart courses, with university societies and local Scout groups.

For more information, please contact Sam Williamson.