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Capturing Energy from River, Tide, and Ocean Currents: an Example of Efficient, Practical Technology Using the Helical Turbine
Scott Anderson, Coordinator The Tide Energy Project Near the Mouth of the Amazon
Summary: The immense amounts of energy available from river, tide, and ocean currents are going unused. The helical turbine now makes it efficient and practical to capture energy from flowing water. This can be done with little environmental impact and on small to large scales. The case of a small-scale application with tide currents is presented. An initial evaluation of the potential of water-current energy at specific sites can be done easily and inexpensively. This energy could benefit a large number of developing countries, in particular, Small Island Developing States. Technology to capture the energy of water currents: the helical turbine. The energy of water currents can be captured in an efficient and practical way using the Gorlov helical turbine. A schematic view of a helical turbine mounted in a frame with a generator is shown below.
The helical turbine is designed for hydroelectric applications in free-flowing water. It is self-starting and smooth-running. It operates well in river, tide, and ocean currents.
Because they operate in free-flowing water without expensive dams, helical turbines have little environmental impact. They will not block fish migration or the transport of sediments and nutrients. Also, they will not stop the passage of ships. Helical turbines can be used to capture water-current energy at different scales. Individual turbines can be used on a small scale as shown in the example that follows. They can also be used at larger scales by mounting a number of standard turbines on one shaft in deeper waters, or on a number of shafts in wider waters. A case of capturing tide energy in a simple, inexpensive way. In order to capture the energy of the tides near the mouth of the Amazon River in Brazil, we built a prototype station there for small-scale generation of electricity in rural areas. The photograph below shows a six-blade version of the helical turbine used at the station.
This turbine was built locally by a mechanic and a welder. The only outside components were the helical turbine blades themselves.
The rest of the generating system at the station was also built by local craftsmen from locally available materials. The complete generating system is shown below.
For this prototype station at this site, it is expected that the energy produced would be sufficient to meet the basic needs of 10 households, at World Bank standards for rural electrification using solar energy. For more information on this project, see The Tide-Energy Project Near the Mouth of the Amazon available online at: http://www.globalcoral.org/Tide_Energy_Overview_English.doc Evaluating the energy potential of water currents at a site. In order to generate electricity effectively with the helical turbine, the flow of water at a site must be at least 1.5 meters per second. The amount of energy that can be captured depends on how long the current flows at this speed, or faster, and how frequently this occurs. Therefore, it is necessary to make an evaluation of the energy potential at each site with river, tide, or ocean currents to determine: (a) if this minimum rate of flow is reached; (b) for what length of time; and (c) how often. An initial evaluation of energy potential can be done easily and inexpensively using a wristwatch and a floating object attached to a line of known length. Because the features of river, tide, and ocean currents are somewhat different, the specific procedures for making evaluations of their potential are also somewhat different.
For more information on evaluating river-current energy potential, see For more information on evaluating tide-current energy potential see The Potential of Tidal Energy for Small Island Developing States Author contact information: Scott Anderson, PhD, Coordinator, The Tide-Energy Project Near the Mouth of the Amazon e-mail: sdand@bellsouth.net telephones: +1 (352) 376-0799 / +1 (352) 246-8246 (mobile) |
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