Instead of depending on a concentrated source of flow by storage of water the micro plant at Alberto Brenes depends on a pipe that was installed at the edge of the river. A small barrier was constructed to concentrate flow but not stop it. The artificial barrier acts as a funnel, directing a minuscule portion of the flowing water from the river into the pipe that leads to the plants turbine. This design also allows for sediment to keep flowing through the river naturally, providing nutrients to the different walks of life that thrive on it. The minor alteration of river flow is nothing in comparison to macro projects.
Impacts on Wildlife:
Micro hydro projects do a fantastic job at preserving plant, fish, and animal communities. Most designs, including the one at Alberto Brenes, require minimal alteration to the natural environment and therefore hardly alter the rivers they are found in. It is more common for the turbines used in macro designs to injure or kill aquatic life as creatures get caught in the blades. This problem is almost nonexistent when it comes to micro-hydroelectricity. The only incident recorded at the Albert Brenes plant regarding wildlife being harmed was when a baby coati accidentally got sucked into the intake pipe and made it all the way to the turbine. This was a very unfortunate event but very minimal in terms of impact, especially when compared to other projects.
Wildlife is also dramatically affected by reservoirs because as sediment collects the nutrients allow for a wealth of growth. As algae and other plant life begin to flourish they create unnatural competition for different plants an animals. Ecosystems remain far more balanced in the presence of micro hydro plants, as they do not have to suffer from these large surpluses of nutrients. Other than an increase of sediments and nutrients, macro plants introduce far more chemicals into the water that are necessary for the involved machinery. Animals that depend on the rivers located past these hydro plants can suffer from these chemicals. Micro projects have a much lesser impact in general.
Impacts on River:
Hydroelectricity takes a toll on the rivers and streams where hydro projects are located. Fish face drastic changes in their ecosystems when rivers dry up at certain spots, which is common when dealing with hydroelectricity. This problem is also much more relevant when talking about macro projects opposed to micro. It is more common with macro projects because reservoirs hold more stagnant water that is more easily evaporated, so when the flow is taken away the water has a chance to heat. The Albert Brenes Biological Reserve does its best to have an extremely low impact on nature, its main purpose being research of an unaltered environment. It is for this reason that a micro plant is the only acceptable form of hydroelectricity on site. A macro plant would severely alter the state of the river.
Changes in the water levels along with lack of vegetation on the bank of a river can easily lead to erosion. The lack of vegetation makes it possible for water to begin cutting into the banks of reservoirs and rivers alike. As erosion increases there is a larger chance for nutrients to make their way into the water. In this sense, erosion also leads to increased sedimentation. Most problems involved with hydroelectricity are interrelated; the reservoir collects water, the water evaporates, evaporation leads to erosion, and erosion leads to increased sedimentation. Micro plants deal with these problems on such a minimal level that the difference between micro and macro seem like night and day.
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| Micro-Hydro facility turbine at Alberto Brenes Biological Reserve |
Micro Hydro Design:
The design of a Micro hydro-electric facility follows the same idea of a large commercial hydro-electric plant (such as the San Lorenzo facility). The only difference in design is that micro-hydro stations are typically built to have a minimal environmental effect. Therefore these facilities will typically be run of stream, or only have a very small reservoir at the top of the whole facility. In the case of the micro-hydro plant in Alberto Brenes Biological Reserve, hundreds of feet of pipe are used to divert only 20% - 30% of the total flow of the river. The pipe, known as the penstock is approximately 130m long. The penstock veers away from the river in order to gain head above the turbine. The penstock has a few small features that are critical to it’s maintenance and efficiency. Most important is a grate placed at the very beginning of the penstock in order to block flotsam and rocks from entering the system. The other two features are holes drilled in the top of the penstock to let air escape, and a shut off valve, which can be turned to cut off the water flow while no one is on the reserve. After the penstock the water falls downhill approximately 30m towards the turbine. As the water falls, the pipe gets smaller and smaller to increase the speed of water flow. The water exits from the pipe through a nozzle close to that you would find on a fire hose. At this point the pressure of the water is extremely high. The stream of water hits the turbine and the turbine runs the generator. The type of turbine used at Alberto Brenes is called a pelton wheel. Through a set of flywheels and pulleys from the turbine to the generator the rotations per minute go from 84 rpm to 756 rpm. Through this DIY micro hydro-electric facility Alberto Brenes biological reserve is 100% self sufficient when it comes to energy.
Energy and Electrical Components:
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| Electrical intake box at Alberto Brenes Reserve. |
Micro Hydro-electric projects are hydro-electric projects with up to 100 kilowatts of productivity. A Micro Hydro project with this output can power around 50 homes, each with a few lightbulbs and a television or radio. In technical terms the Alberto Brenes Micro Hydro facility is not actually Micro Hydro, because it does not produce enough power. The hydro facility in Alberto Brenes Biological Reserve is actually a “Pico-Hydro” plant. A Pico Hydro plant produces under 5 kilowatts of energy. This is usually enough energy to power a few remote houses, or in this case a Biological Reserve field station. The use of a Pico Hydro plant in Alberto Brenes is so useful that sometimes they have too much energy. A certain amount of lights must be kept on the entire time the plant is running in order for the circuits and such to not go over capacity. At any given time that the hydro plant is running, the reserve field station has 100 volts of energy available. To find the total wattage of the reserve’s facility I would need to multiply the total Volts x Amps. Unfortunately the number of amps was unavailable. I assume the total wattage is just above 1 kilowatt.
What does it take!? Why should it be used? Micro-Hydro:
In order to make a Micro-Hydro facility like the one found in Alberto Brenes Biological Reserve the first and most important component is…..water. Yes of course it’s water, but a substantial source must be chosen, and the source cannot fluctuate in water level too much between seasons. After a good water source is found, the surrounding geography must be right. The river must have a decent slope to it in order to build head. Creating head can be a strenuous task. Usually hundreds of feet of trench or pipe must be laid. From then on more pipe must be laid for the water to fall the distance of the head to the power station where some electrical knowledge is required. The turbine and generator must be mounted and required electrical equipment is set up. Making a micro-hydro electric facility is a very easy task and should be a strategy implemented in more communities around the world. A Micro-Hydro facility can power anywhere from 1 lightbulb to 100 homes. It is a great source environmentally friendly energy at the community level. Building a facility can be done cheaply and properly by anyone in any community. Micro-Hydro electric facilities are an asset that is not used nearly enough throughout the world.
AUTHORS: Matt Richards, Blake Lecroy
