Example of Microhydro-electric turbine
Activities and Findings
In February 2013, CEN and a small team of residents of the community of Suruacá conducted tests in the area and evaluated their findings:
- After releasing a two-liter, partially submerged water bottle attached to a 20-meter cord, two people remained in a canoe about 10 meters downriver from the team in the canoe that released the bottle.
- Someone in both canoes timed how long it took for the cord to become taut.
- These measurements were compared to the measurements taken at various observation points.
You can view the measurements we took on the project's page on our organizaton's website.
Based on local observations and the measurements taken, the evaluation team concluded that micro-hydrokinetic technology is not a viable option to meet the community’s electricity needs at either site. Based on the measurements of the water current the team made along the Tapajós River near the community of Suruacá — and consistent reports by local fishermen and riverboat captains that the current speed near the community of Surucuá, approximately 50 kilometers to the south, were of similar speed to that near Suruacá — the team determined that it was not worth the additional expense to travel to Surucuá to take measurements.
Long-Term Energy Alternatives
Although CEN has concluded that a micro-hydrokinetic implementation is not a suitable option for meeting the electricity needs of either Suruacá or Surucuá, there are still several other long-term energy alternatives for the communities to pursue. These include:
Constructing a transmission line from the expanded capacity planned at the micro-hydroelectric generator at the Cachoeira do Aruã, about 100 kilometers to the northwest of Suruacá: Unlike the much larger dams that are planned to the south, this installation has very limited environmental impact. While IBAMA (the Brazilian environmental agency) and the Ministry of Education support the project, financing for its construction has been delayed for a considerable time by the local electricity concessionaire. However, local agencies and nongovernmental organizations are continuing to attempt to address the obstacles.
The community has petitioned the Prefecture of Santarem for a new 600 kVA diesel generator to replace the community’s current 30 kVA generator. The new generator would produce 20 times the current generator’s capacity — enough to account for many years of future growth — for less than 50% more fuel. The current proposal details using the new generator for the same number of hours as the current generator (four hours, three to four nights a week); however, it could become feasible to expand the number of hours over time. It is unlikely to be economically feasible to operate the generator 24 hours a day and seven days a week, as this would continue to be an obstacle for meeting key needs such as refrigeration and health.
Install small generators to be used for electricity needs during the hours when the community generator is not being used. Such an approach would be very costly for long-term use since the common small generators in use today consume over one liter per hour but serve only one family. It could be an option for situations, such as tooling and woodworking shops where the generators could be used only when needed.
Several positive outcomes did result from the project:
- Identified a locally designed and produced micro-hydrokinetic turbine with lower water current velocity requirements
During consultations with a Santarém-based engineering firm, Indalma Industria & Comércio, CEN learned that they have developed a micro-hydrokinetic turbine rated to function efficiently with currents as low as one meter per second. While this would not be suitable for use on the Tapajós River near Suruacá, it might serve the needs of communities along the much more quickly flowing Amazon River or other parts of the Amazon. Indalma estimates the costs for meeting the electricity needs using their turbine designs to be between $3,500 to $5,000 USD per family, which is considered very reasonable.
- Addressed the challenge of seasonal river level variance along the Tapajós River for locating micro-hydrokinetic turbines
During the dry season, the water level drops several meters and the river becomes narrower. It lowers over one kilometer compared to rainy season water levels. This requires the team to locate the turbine well over a kilometer from shore so that it doesn’t have to be moved or move it as the water recedes. If the turbine were moved, it would require someone to regularly monitor the water level and to relocate it several times a year, which is a process prone to potential mistakes. Permanently mooring a turbine on a platform away from the shoreline requires the team to ensure it isn’t a navigational hazard.
Locating the turbine slightly off the riverbed offshore eliminates both problems and appears to be the most feasible solution.
We concluded the most viable option for deepwater locations is to locate the turbine off the river bottom and to run an underground cable to the shore, using a solution developed by Indalma. One challenge with this solution is that the turbine needs to be located at a significant distance from the shoreline, which would require the use of a heavy gauge cable, leading to a significant increase in the project’s cost.
Regardless of whether a turbine is installed permanently offshore or not, the need to locate the turbine over one kilometer from shore, for even part of the year, would require the use of higher gauge electric cables in order to prevent heavy loss of electricity.
- Documented the prevailing water current along the lower Tapajós River
- Further strengthened community experience and ability to manage infrastructure projects, especially energy
Although the community developed an impressive ability to manage its current public infrastructure, it has not been closely involved in decisions effecting the provision of electricity to the community. Overall, community members are not well informed about the feasibility and obstacles to options available.
For example, about five years ago, CEN helped put the community in touch with a local engineering firm to investigate the feasibility of using a small waterfall about nine kilometers from the community to build a micro-hydroelectric dam. Although the engineer originally felt the project was potentially feasible, he later switched his opinion when more data became available. Community members have significantly different understandings of why the generator wasn’t built. Some understood that subsequent data changed the engineer’s opinion. Others felt the engineer didn’t care enough to execute the project. No one contacted the engineer to gain a full understanding, and the engineer didn’t sit down with the community to communicate his findings.
By closely involving the community leadership, and especially those members who are most responsible for managing the community’s energy infrastructure, we helped them better understand the detailed requirements. Together we determined that the proposal wasn’t feasible and why.
- Clarified for the community leaders why an earlier evaluation of a micro-hydroelectric project was deemed not to be feasible
During discussions with community leaders, CEN Director Bob Bortner helped community leaders understand why an earlier micro-hydroelectric project was deemed unsuitable, as well as provided an update on the status of the possible construction of a transmission line to the Cachoeira do Aruã, and shared the information and contacts with the community leaders so they may follow up if needed.
Although we concluded that the water current along the Tapajós River is not strong enough for a micro-hydrokinetic turbine to operate efficiently, the project built upon our ongoing leadership development efforts in the community by closely involving community leaders in the discovery and evaluation process for accessing the electricity they need. Residents became active participants in the process rather than bystanders like they have been in the past.
Satellite photo of where we measured