Large-scale hydroelectric power generation facilities have, since the early part of the twentieth century, been technology staples of industrialized society, providing power grids across all the continents with the energy to move industry and provide centers of population with domestic and commercial electricity. While most people are aware of the societal benefits of large-scale hydroelectric power generation, many are not as familiar with the adaptability of smaller hydroelectric power generation systems designed for small communities, remote lodges, even for single-residence dwellings. There are two conditions that are required to generate hydroelectric power, either on a large or small scale. These are: 1) A source of flowing water; and 2) topographic relief in the landscape to provide the flowing water with potential energy.
Hydroelectric power generation, whether large- or small-scale consists of nothing more than channeling the water down a gradient and introducing it into a turbine, which generates current. There are two types of hydroelectric technology, one which generates alternating current (AC), the second which generates direct current (DC). AC-direct power generation systems include the large-scale power generation systems typically located at the base of large hydroelectric reservoirs. These systems are for generating large amounts of electricity to be used in a regional power grid. Smaller AC-direct systems, called mini-hydro systems are used for smaller water sources but can still generate sufficient power to drive small communities, hotels, lodges, certain commercial installations, and large well-anointed households. DC-power generation systems, also called micro-hydro systems, are for very small or seasonal water sources. Although DC-powered appliances can be used by the power generated directly from these systems, typical micro-hydro installations include an inverter, which converts DC power to AC power for use with conventional household appliances and electrical fixtures.
The economic benefits of hydroelectric power generation depend directly on the resources available to the facility in question. For remote residences, lodges, mining camps, and other commercial installations where no electrical grid is available to satisfy energy demand, hydroelectric power generation is almost always advantageous economically over the use of diesel, gasoline, or propane generators. Hydroelectric power generation is normally favorable economically over solar power generation as well, presuming the resources are available for a hydro installation. For areas served by grid electrical power, economic return can normally be gained only across a long period of time.
The economics of hydroelectric power generation are favored by the very low maintenance and operations requirements of such systems. Because hydro systems can be almost completely automated, once they are installed and operational, there is almost no operator attention required at any time, and maintenance needs are normally limited, depending on the complexity of the system, to a yearly series of routine maintenance tasks. Correspondingly, the only real cost of a hydroelectric power generation system, is the capital cost of equipment procurement, installment, and design and engineering fees. For similar amounts of power generation, hydroelectric power generation systems nearly always carry lower capital costs than comparable solar power generation systems, which also have higher maintenance requirements.
The environmental benefits of mini and micro-hydroelectric power generation are also substantial, on scales ranging from local to global. Most importantly, hydroelectric power generation is a renewable energy resource. The water used to generate power is borrowed from a watershed always in accordance with established standards of what is permissible for sustained aquatic health and returned to the watershed subsequent to power generation. Since the water has no contact with oils or greases, there is absolutely no contamination of this water, and it is returned at the same temperature at which it was extracted. There are no fuels used in hydroelectric power generation; therefore there are no emissions such as those emitted by gasoline, diesel, or propane generators. Finally, local hydroelectric power generation reduces societal electrical demands, however slightly, thereby reducing, however infinitesimally, our dependence upon nuclear power plants and coal and oil burning power plants, all of which are at the forefront of global environmental concerns.
There are two fundamental design variables governing the sizing and applicability of a hydroelectric power generation system. These include the available flow rate of water (expressed commonly in gallons per minute, but also cubic feet per second, liters per minute, etc.) and the vertical relief between the site of water intake and the site of power generation. A wide variety of additional information is necessary to design the appropriate hydro installation for a particular energy demand; however, with just these two pieces of information it is possible to establish the approximate output possible and to establish if the resources available are more appropriate for a mini- or a micro-hydro installation.
Our experience in the rigorous environment of remote building sites in Costa Rica is that hydroelectric power generation is a robust source of energy to remote homes and lodges far removed from the national electrical grid. Although the same may not be said for industrialized societies, where grid power is more stable, privately owned hydroelectric plants are consistently more reliable than the nation's power grid, which often experiences frustrating power failures. A back up diesel, propane, or gasoline generator is capable of providing a redundant power source for those rare instances in which hydroelectric power is disrupted for annual maintenance or the rupture of a pipeline by a fallen tree. For environmentally sensitive locations, such as the tropical montane rain forests of southern Costa Rica, hydroelectric power generation has the additional benefits of greatly reducing irreplaceable fossil fuels as well as eliminating their greenhouse gas emissions.