Overview of Hydro-Electricity in Costa Rica (TSP Paper)

      Humans have been utilizing hydraulic power from rivers and streams for centuries. The Greeks and Romans began using waterwheels to grind corn in the third century B.C.E. and the Chinese had their own independent inventions by 100 B.C.E., these designs were very basic yet practical. Hydropower is a clean source of energy in that nothing needs to be burned to harness it. The hydro cycle replenishes itself, hence the reason why humans have been taking advantage of it for hundreds of years. Costa Rica is one of many countries that have a heavy dependence on hydropower, generating over eighty percent of the country’s electricity.
     
      Hydro technology has been drastically improved in the past few centuries. It wasn’t until the 1770’s that French engineer Bernard Forest de Bélidor, published research on the water turbine that would act as the foundation of modern hydro turbine development. The French were extremely proactive in engineering turbines for hydroelectric use. The San Lorenzo macro hydro-plant the class visited used two turbines designed by a French engineer. The Francis turbines at this site are capable of producing 8.5 mega watts each. Macro scale hydro projects in Costa Rica such as this one are relatively new. Large generation of electricity based on hydropower in the country did not begin until 1949, when the Costa Rican Electricity Institute (ICE) was founded to manage electricity and telecommunications in the country.

      While hydroelectricity is much cleaner than burning coal, natural gas and oil for electricity, there are still some environmental impacts that are tied into its generation. One of the most apparent impacts is had on the aquatic life that thrives in rivers and streams near hydroelectric sites. In the majority of macro designs, a reservoir is constructed in order to store water for its plant. These reservoirs affect wildlife and the natural environments they are transplanted into. The dams built to hold the water stop fish from being able to navigate water systems normally. As migrations of some species are brought to a halt, some populations severely suffer. Populations down stream also suffer from loss of water as the hydro-plants alter the natural flow of the river. As some species decline in population other species that thrive in warmer slower waters can see population spikes near reservoirs. All of these factors contribute to the disruption of aquatic ecosystems.

San Lorenzo Dam

      Another sizable problem that goes along with hydroelectricity is sedimentation, this is probably the most technical problem dams face today.  Sedimentation builds up in reservoirs and takes away from the amount of storage available for water. Maintenance is constantly required at large scale dams to try to prevent this problem from happening. At San Lorenzo, the staff does an annual cleaning of its reservoir to remove sediment and increase energy production. The sediment is placed outside of the river in a sort of heap. If this sediment was utilized for purposes such as agriculture it could be highly beneficial.

      There are also doors found at the bottom of the large reservoir that are opened when the amount of sediment is clearly increasing in an effort to combat the problem. When sediment gets trapped by the dam it creates a functional problem for the hydro-plant but it also creates a problem for the river and the species that inhabit it. As the sediment stops at the dam it prevents nutrients from traveling downstream and therefore can cause nutrient deficiencies at some parts of the river. The reverse affects of this problem as that there are too many nutrients near the reservoir where the nutrients collect. The unnatural construction of hydro dams creates very unnatural problems.

      Currently hydroelectricity is being used in 150 countries.  In total, 16% of the electricity in circulation around the globe is harnessed from water(which equals 3,427 terra-watt hours).  Here in Costa Rica, 82% of the total electricity in the grid comes from water.  The country produces more than 90% of it’s total energy from renewable sources.  Costa Rica is only going to move further with hydro electricity.  Currently the largest facility in the country is the Presa Sangregado dam.  The dam is on the south east shore of Lake Arenal and produces 157 megawatts hours of energy which is all sold and regulated by the ICE (Instituto Costarricense de Electridad).

       Costa Rica has great potential for hydro-electricity.  The country has plenty of rainfall throughout the year and a landscape perfect for building dams and reservoirs.  The perfection of the land is due to the steep mountains formed on the Central American isthmus and bounty of rivers with consistent waterflows and deep valleys.  As a whole Costa Rica has a predicted hydro-electric energy potential of 25,400 MW.  Considering the size of the country, this number is very high.  Costa Rica has a total of four hydro-electric plants that are of a notable size: Presa Sagregado(largest),  Cachí (three 34 MW turbines), Angostura( three 70 MW turbines), and Corobici (additional component to the Arenal Reservoir). Although these are all very large hydro projects they do not produce even close to all the hydro-electricity in Costa Rica. Many of the Hydro-electric producing facilities in Costa Rica are small or Medium scale facilities due to the medium scale needs of the country.  One example of a medium scale Hydro Electric plant in Costa Rica is the San Lorenzo dam.  The dam is not built on a large river and does not alter the flow as drastically as many other hydro-electric facilities do.  The plant produces 17 megawatts of energy and is a great display of a Costa Rican hydro-electric plant.

       The last type of Hydro Facility found in Costa Rica is a Micro Hydro facility.  These facilities are the most environmentally friendly out of all other facilities because of their run of the river design.  They produce anywhere from 5kw to 100kw of energy.  An even smaller design is Pico Hydro, which is a facility that produces under 5kW of energy.  The two of these designs have the purpose of powering small communities.  Pico and Micro Hydro facilities are not government owned and are not built with the intention of selling the energy.  Typically these types of facilities are used as a power source in remote settings that are not connected to the power grid.  They can have the purpose of powering anything from a light bulb to a community with as many as 50 homes. Micro hydro-electric facilities are very simple and should be used more across the world.  The design only needs a flow of 2 gallons per minute, or a drop as low as two feet for a viable power source.  The design is perfect for many areas of Costa Rica and should be an implemented strategy in rural and indigenous areas.

       Harnessing the power of water has been a practice for much of written human history.  Even harnessing the mechanical power of water is nonetheless using the energy of water.  Nowadays water is one of the main electrical sources of the world.  Due to the growth of the hydro-electric industry it has become a large part of the global economy and is also a large part of international politics.  As the industry grows knowledge of new practices and the impacts of hydro-electric facilities are spreading.  The concept of Hydro-electricity is a double standard when it comes to environmental impacts(renewable energy vs. disruption of river flow).  In the future we will most likely see an abundance of hydro-electric practices from pico to macro sized.

AUTHORS: Matt Richards, Blake Lecroy