BRAZIL:
An Energy Source Both Cheap and Eco-Friendly
Mario Osava

RIO DE JANEIRO,  (IPS) - Very low-cost electricity that is not just clean but potentially beneficial for the environment, and comes from a flexible source that can be set up on any river without altering its course is the promise a Canadian company made in Brazil this week.

Presented as "revolutionary" technology, the most important means of generating power "in the near future" is a floating turbine, developed in Brazil by Eco Hydro Energy Ltd., a company based in Vancouver, Canada.

The innovative device uses the power of the river's flow to turn a rotor with mobile blades. The rotating movement feeds electromagnetic generators that produce electrical energy. There is no need for waterfalls, and the turbine can be anchored in the river in different ways.

The turbine is installed on either fixed or floating platforms, the latter having the advantage of rising and falling with the river level, explained Wilson Pierazolli, an engineer at the Federal Centre of Technological Education (CEFET) in Minas Gerais, where a prototype of the turbine was evaluated, and research is being conducted on this alternative energy source.

Slow-moving water, like that found in some rivers in the Amazon region and other plains, is no impediment to the working of this system. It just requires bigger equipment to make use of the greater water volume, depth and breadth of the rivers, Pierazolli told IPS.

The turbine operates half submerged, damming back the water, which then flows under it more strongly and at higher speed, he explained.

A turbine with a total diameter of 30 metres and 160 metres long on a great Amazonian river can generate 240 megawatts per hour, enough electricity to supply a city of nearly two million inhabitants, according to Colin Regan, founder and director of Eco Hydro in Vancouver.

Regan and Johann Hoffmann, an Austrian who has lived in Brazil for 20 years, invented the technology. They were thinking of supplying electricity to isolated towns in the Amazon region, where there are 23,000 kilometres of rivers that mostly lack the gradient necessary for conventional hydroelectric power stations.

Floating turbines have many advantages, according to the company. They do not require dams which flood extensive areas, they have almost zero environmental impact, and they can generate power 24 hours a day. They even help to decontaminate rivers, as the turbulence they produce oxygenates the water, thus improving conditions for aquatic life.

The main advantage, however, is their low cost, since large construction projects are unnecessary. The company estimates the required initial investment at 450,000 dollars per megawatt capacity, which is half the cost of gas-burning thermoelectric power stations and one-third the cost of hydroelectric plants or wind energy.

Operating costs are also less than one-third of those using other sources, such as natural gas, hydroelectricity and wind power. Only nuclear energy comes close at 25 dollars per megawatt-hour, compared to 15 dollars for floating turbines.

Also, there are no climate-changing greenhouse gas emissions produced by the turbines, an important improvement on power stations that rely on fossil fuels like coal or gas.

River water flows constantly in the same direction, and can be re-directed or their current altered to improve energy yield, unlike winds which are not constant and can change direction at any time, Regan said.

Furthermore, wind energy is still very expensive, requires heavy subsidies, and the windmills are an eyesore and occupy huge areas, "sometimes killing birds," he added.

Eco Hydro will now try to promote floating turbines in other countries, and to attract some large energy or industrial company to take on the challenge of manufacturing a river turbine with a capacity of "at least 50 megawatts," Regan announced.

He estimates that his technology can be used to build turbine systems generating up to 500 megawatts. Depending on the river, floating turbines can be installed in arrays, a fixed distance apart.

As for research, the next step is to develop mathematical models to find the best way to maximise energy production in each river situation by computer simulation, says José Raimundo da Luz, another engineer with CEFET, which has made a name for itself in small-scale hydroenergy research.

The turbines present "another option" for generating power from water, but it's still in its early stages, and the energy yield in different conditions, especially on a large scale, has yet to be confirmed, was the evaluation Eliab Ricarte gave IPS. Ricarte is a researcher at the Ocean Technology Laboratory of the Federal University of Rio de Janeiro.

The technology looks promising in smaller rivers, but its efficiency in converting water flow energy into electricity must be assessed, he said. Exposing it to evaluation by the scientific and technological community is one way to do this.

The findings to date are based mainly on the operation of a small prototype installed on a stream in Itabirito, in Minas Gerais state. But this isn't enough data to calculate the efficiency and the real costs of a power plant that can generate hundreds of megawatts, Ricarte argued. His own work centres on a project to generate energy from ocean waves.