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Practivistas Chiapas estudio sobre la factibilidad de microhídro

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This page is a project page in progress. Please refrain from making edits unless you are a member of the project team, but feel free to make comments using the discussion tab. Check back for the finished version on August 12, 2010.


Contents

Team Micro Hydro

Project Description

Objective/Objetivo

We are a small team of Humboldt State University undergraduate students working on a project to investigate the feasibility of constructing, installing, utilizing and maintaining a run-of-the-river micro-hydro system to provide electricity for a rural community near San Cristóbal de Las Casas, Chiapas, Mexico. The feasibility tests will include studies on potential power available from several rivers and a survey of the available building materials and operation costs. If the feasibility study results recommend the implementation, design, and construction of this project, it may be completed by another party in the near future. Such action would be coordinated with the community that would benefit from the micro-hydro system.

Somos un pequeño equipo de estudiantes de licencia en Humboldt State University trabajando en un proyecto para investigar la factibilidad de construir, instalar, utlizar y mantener un sistema de micro-hídro para proveer la electricidad para una comunidad rural cerca de San Cristóbal de las Casas, Chiapas, México. Las pruebas de la factibilidad van a incluir estudio del poder potencial que se puede extraer de varios ríos y un estudio de las materias disponibles de construcción y costos de operación. Si el estudio de la factibilidad recomienda la implementación, el diseño y la construcción de este proyecto, quizás será implementado por otra parte en un futuro cercano. Tal acción sería coordinado con la comunidad que beneficiaría del sistem de micro-hídro.


 
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Background/Antecedentes

Hydro power is already a common method of energy generation in Mexico. Mexico's total installed power capacity from the year 2000, which utilized 20% of the Mexican Energy Supply (6368 PJ) was 36,697 MW. The capacity profile was: fuel oil 38.9%; hydro electricity 26.2%; natural gas 15.7%; coal 7.1%; dual 5.7%; nuclear 3.7%; geothermal 2.3%; 0.3% diesel. Hydro power provides 26.2% of Mexico's electricity, but mainly from large dams that greatly disrupt the ecosystems surrounding the rivers.[1] The aim of this project is to investigate run-of-the-river hydro power systems which generate less electricity but have a more benign environmental impact. The autonomous communities and the mountainous terrain of Chiapas appear to indicate positive circumstances for micro-hydro power. The drop in elevation may provide the amount of head necessary for sufficient energy generation from a micro-hydro power system.

Although Chiapas remains one of Mexico´s poorest states, it contributes a great portion of the country´s electricity. Unfortunately, only 8% of the electricity users account for 50% of the state´s electricity use because the Federal Electricity Commission (EFC) levies tariffs on communities that cannot afford to pay for electric power.[2] For this reason, many local Zapatista and autonomous communities resist paying for electricity and have learned how to maintain their own repairs on power lines. [3] Such communities may therefore benefit from the increased independence provided by micro hydro power for their lighting needs, refrigeration of medicines and maintenance of communication systems.

El poder hidroeléctrico ya es un método comun de generar energia en México.Lo constituye 26.2% de la electricidad del país, pero es generado principalmente por presas grandes que causan daños a los ecosistemas que rodean los ríos. La meta de este proyecto era investigar la factibilidad de los sistemas de micro-hídro, cuales por definición generan menos electricidad pero tienen un más benévolo impacto medioambental. Las comunidades autónomas y el terreno montañoso de Chiapas parezcan indicar circunstancias positivas para el poder micro-hídro. El descenso en la elevación quizás provea la cantidad de caída necesaria para generar suficiente energía de un sistema del poder micro-hídro.

Aunque Chiapas sigue siendo uno de los estados más pobres de México, el estado contribuye una gran porción de la electricidad del país. Desafortunadamente, sólo 8% de los usuarios de la electricidad constituye para 50% del uso eléctrico del estado porque la Comisión Federal de la Electricidad (CFE) impone tarifas a comunidades que no pueden pagar para poder eléctrico. Por eso, muchas cercanas comunidades Zapatistas y autónomas están en resistencia de pagar para la electricidad y han aprendido mantener sus propios cables de la luz. Tales comunidades pueden por consiguiente beneficiar de la independencia aumentada aportado del poder micro-hídro para sus requirimientos de la luz, refrigeración de las medicinas y mantenimiento de los sistemas de comunicación.

Local Energy Alternatives

The main form of power generation in Chiapas is large scale hydro power. Cañon de Sumidero is a popular tourist attraction and at the end of the tour a large dam and hydro power plant are visible. This dam is called Chicoasen and it is the 5th largest in the world. Large scale hydro power has several major drawbacks. According to New Scientist, [4] hydro power dams produce significant amounts of methane and carbon dioxide. They also destroy ecosystems and disrupt the migration of fish populations and cause flooding.

Micro Hydro in Latin America

  • Chel, Quiché, Guatemala [5]
    The rural community of Chel is located in the northern region of Quiché, Guatemala. This area was greatly affected by the Guatemalan Civil War, which left it without access to water, energy or transportation. The people of Chel put their trust in Fundación Solar (a Guatemalan non-profit organization) to organize the planning and installation of the micro hydro system. This represented a big step towards healing the fear of the outside world instilled by the massacre of Chel during the war. The people worked together to build a road into the community and carried the necessary supplies on foot from town. The micro hydro power system was built in 2000 and provides 110 kilowatts of power for 440 homes. The community was very enthusiastic about the quality of life improvements created by having electricity. These improvements included purchasing a solar powered satellite telephone that generated an income for Chel because it saved surrounding communities a 10-hour journey to the nearest phone. The success of the phone then helped them afford a fax machine, computer and truck for transporting supplies.  The introduction of micro hydro power empowered the town of Chel to plan for their future instead of being fearful of outside life.
  • La Pita del Carmen, Nicaragua[6]
    The community of La Pita del Carmen is located in northern Nicaragua and has a population of about 400. Northern Nicaragua is home to many relocated combatants of the 1980-90 Nicaraguan Civil War whose communities lack electricity and are located far from any federal power infrastructure. La Pita del Carmen is located 70 kilometers from the nearest power source, thus a micro hydro system provided them with a cost effective way to bring electricity to the town and put them on track for future economic growth. The Association of Renewable Development Workers (ATDER) assisted with the coordination of the system that brought electricity to homes, farmers, businesses and the local school for the first time. The micro hydro system on the La Pita River began operating in 2000 and provides the people with 120,000 kWh per year. It is one of four micro hydro installations planned by ATDER in Northern Nicaragua in the next few years. The community also benefitted from overcoming differences forged by the civil war in order to work together towards a mutually beneficial goal.
  • Camata, Department of La Paz, Bolivia [7]
    Camata is a small subsistence community of 70 households whose people live mainly by producing coffee, chile and corn. The hydro installation provides 27 kilowatts of power that provides electricity to homes, a police station and a school as well as a new agro-processing plant. The agro-processing plant is the perfect complement to the micro hydro installment for Camata because the plant uses the same power during the day that households use in the evening. The plant helps both save and generate income for Camata: it provides the locals with a way to process their crops of coffee, corn, and chile instead of selling their crops to someone else for processing. Members of surrounding communities can sell their products to the plant instead of taking them to town. The community formed the Committee for Electrification after the suggestion that their location was ideal for micro hydro by the Hydraulic and Hydrology Institute. The Committee for Electrification was responsible for the planning and construction of the hydro system and agro-plant and now oversees power regulations and system operations.

Advice from a Local Water Engineer

During our visit to the technical department of the National Water Commission (CONAGUA) we spoke to a water engineer. He relayed some information that his organization and other groups working on feasibility studies discovered about micro hydro feasibility in San Cristobal de Las Casas. It appears that much like the City of México, D.F., San Cristóbal de Las Casas was previously located on top of a lake. As the population grew a solution had to be found to remove the water from the city. A tunnel was constructed and the water was removed from the city and transported to barren land. The water from the lake that was San Cristóbal suddenly made this land viable for cultivation and a farming community grew there. Previous hydrological and micro hydro studies in San Cristóbal concluded that micro hydro systems would only be efficient during the rainy months of the year in the mountains far outside the city. In order to reach an ideal cost-benefit ratio, the system must be closer to the center of the city. This presents a problem in disrupting the irrigation of farming communities that were created by the tunnel. Although we are researching run-of-the-river systems that do not impede water flows to these communities, micro hydro systems are therefore seen as a threat to their livelihood. Near the center of San Cristóbal there exists much resistance to micro hydro and heightened tension whenever the topic is broached. [8]

Criteria

Criteria Description Weight
Aesthetics Meets cultural needs. 6
Community Involvement Community has interest and need. 5
Cost Efficiency Cost/kW, availability of local materials, and low maintenance. 9.5
Educational System educates community about sustainable energy. 6
Environmental Effect Diverts an appropriate amount of water and does not harm aquatic life. 7
Location of Site Close to community with access to a continuously reliable water source. 9.5

What is Micro Hydro?/¿Qué es Microhídro?

Most simply, micro hydro systems utilize the kinetic energy of falling water to turn a turbine that converts kinetic energy into mechanical energy. The mechanical energy can either be used to turn water wheels or a generator can convert the mechanical energy into electrical DC power. Micro hydro can be used to power remote communities or provide a renewable energy resource to existing electric grids.[9]

Here is a short video about the basics of how micro hydro electric power works. This is just one example of a micro hydro system. There are many variations and designs they can take on depending on the conditions of your site.

Simplemente, los sistemas del microhídro utilizan la energía cinética del agua cayendo para girar una turbina que convierte la energía cinética en la energía mecánica. Se puede usar la energía mecánica o para girar ruedas de agua o un generador puede convertir la energía mecánica en corriente continua eléctrica. Se puede usar el microhídro para dar energía a comunidades remotos o para proveer un recurso de energía renovable a una red de electricidad que ya existe.[10]

Aquí está una película pequeña sobre las ideas basicas de cómo funciona la energía eléctrica del microhídro. Éste es solamente un ejemplo de un sistema de microhídro. Hay varios diseños que se pueden usar dependiendo de las condiciones de su propio sitio.


Components of Micro-Hydro System/Componentes del Sistema de Micro-Hídro 

A micro-hydro system consists of a diversion of part of the water flow from a river or intake[11], which passes through a debris filter or settling basin[12], and then flows from a forebay tank[13] down a hill in a pipe or penstock[14], where it accelerates through the force of gravity and gains head. The pressure of this stream of water turns a turbine [15] and is then released back to the river flow through a tailrace[16]. The turbine´s mechanical energy can be converted into electrical energy through a generator[17], whose current must be maintained by a controller[18] and can then be transferred through transmission lines [19] to provide electricity for a consumer or business.[20]

Un sistema de micro-hídro utilizaría una toma para desviar una parte del flujo del río. Luego este agua pasaría por un filtro de detritos y un canal a una cámara de carga que está situada por encima de la casa de máquinas. Desde la cámara de carga el agua fluye através de un conducto forzado cuesta abajo de un cerro, en donde se acumula una presión neto, menos la fricción perdida al tubo y empalmes, que le llamamos la caída. Esta caída accelera la fuerza con que el agua gira una turbina y aumenta la cantidad de la electricidad que se puede generar. Luego el agua vuelve al flujo del río por un canal de 'descarga. La energía mecánica de la turbina puede ser convertido en energía eléctrica através de un generador, cuyo corriente hay que ser mantenido por un controlador y luego puede ser transferido através de cables de la luz para proveer la electricidad a un consumidor o una empresa.



Diagram micro.gif

Maintenance of System/El Mantenimiento del Sistema

  • Micro hydro systems require regular maintenance although the cost of this maintenance is generally low.[21] These tasks can generally be completed by one part time operator. Filters must be cleaned on a regular basis, but the number of cleanings can be reduced. By installing the filter at an angle the filter will be mostly self-cleaning. Penstocks must be unclogged after a certain period of time, but the better the filter, the less often the penstock will become clogged. Machinery within the powerhouse must be greased to continue running at optimal performance. If batteries are being used to store energy they must be equalized on a regular basis. Minimum wage in Chiapas is 49 pesos/hour[22] for an estimated 3 hours of maintenance a month, maintenance ends up costing 1,764 pesos annually.
  • Los sistemas de microhídro requieren mantenimiento aunque el costo de este mantenimiento sea generalmente bajo.[23]Por lo general, solamente un obrero puede completar estos trabajos. Hay que limpiar los filtros regularmente, pero se puede reducir el número de las limpiezas. Si se instala el filtro de un ángulo, el filtro se podrá limpiar. Hay que desembarazar los conductos forzados después de un período de tiempo, pero lo mejor el filtro, lo menos seguido que el conducto forzado se pondrá bloquear. Hay que lubricar algunas máquinas dentro de la casa de la turbina para que puedan seguir funcionando al nivel óptimo. Si se usa pilas para acumular energía, hay que igualarlas regularmente. El salario mínimo en el estado de Chiapas es 49 pesos/hora[24] para tres horas de mantenimiento cada mes estimado, el mantenimiento costaría 1,764 pesos cada año.

Pros and Cons of Micro Hydro [25][26][27]

Pros Cons
  • Water is a concentrated and continuous source of energy
  • Energy availability is fairly predictable
  • Very little maintenance is required
  • There is very little environmental impact
  • Greenhouse gases are reduced by reduction of fossil fuel usage
  • Good sites close to communities are hard to find
  • There is not much room for expanding the power generated
  • Variations in seasonal river flow can limit power availability
  • Other uses for the water, such as irrigation, can take away from the desirability of the system
  • Lack of government support and subsidies
  • The additional work and maintenance may be undesirable if the electricity recipients are already grid tied


Feasibility Study/El Estudio de Factibilidad

The feasibility of a micro hydro system is firstly dependent upon the flow and head available at the site, and secondly upon the electricity load and proximity of the system to the community. The feasibility study for a micro hydro system aims to answer the following questions for a given site[28]:

  • How much head is available?
  • What are the maximum and minimum flow rates?
  • How long does the penstock have to be?
  • How much power can be generated at the flow rates?
  • Initial and annual costs?
  • Potential environmental effects of installing micro hydro?

La factibilidad de un sistema de microhídro es primeramente dependiente en el flujo y la caída disponibles en el sitio, y segundamente en la carga de electricidad y la proximidad del sistema a la comunidad. El estudio de factibilidad para un sistema de microhídro trata de responder a las siguientes preguntas para un sitio dado[29]:

  • ¿Cuánta caída está disponible?
  • ¿Qué son los ritmos de flujo máximos y mínimos?
  • ¿Cómo largo tiene que ser el conducto forzado?
  • ¿Cuánto poder se puede generar con estos ritmos de flujo?
  • ¿Cuáles son los costos iniciales y anuales?
  • ¿Hay la posibilidad de afectar al medio ambiente con una instalación de microhídro?

Data Collection Methods

Measuring Flow Rate

There are varying methods on how to measure flow rate. The method we used was to measure a cross-section of a river and time the period of a floating object down the given cross-section. We averaged our ten trials and multiplied the average time by estimated cross-sectional area to calculate a flow in cubic feet per minute. We then converted this to gallons per minute. There is at least one other method for determining flow rate, which involves constructing a temporary dam, then placing a tube out of the dam which diverts the water into a bucket of a specific capacity. Timing the rate at which the bucket fills and then multiplying the average time to fill the bucket by the volume capacity of the bucket gives the flow rate.[30]

Measuring Available Head

The way we measured head was to use a carpenter's level and a calibrated pole five feet long. We had one person walk in front of the level counting strides until his or her feet were in line with the level signifying that the walker had moved up in elevation by five feet. We then moved the level to where the walker stopped and repeated the step. We started measuring from where we would want to place our powerhouse and walked until we reached the elevation of the river. By counting how many times the walker stopped, we could determine the amount of run of the hill, which allows us to determine the necessary amount of piping. By multiplying the amount strides taken by the length of the walker's stride, we were able to determine the amount of available head from the river to the powerhouse.[31]

Power Output Equation

  A common field equation to measure the theoretical maximum power available in a moving body of water is:

\, P_{max} = \frac{Q_{max}*H_{max}*e_{max}}{k}


Where:

  • Pmax=Maximum Power Available (kW)
  • Qmax=Flow (Volume/time)
  • Hmax=Head (Vertical drop in ft)
  • emax=Efficiency of the turbine (use a value of 1 for max power available)
  • K=Unit conversion factor (see table below for some common values)
For Q measured in K is equal to
ft3/min 708 (ft4)/(min*kW)
ft3/sec (CFS) 11.8 (ft4)/(sec*kW)
l/sec 102 (l*ft)/(sec*kW)
gal/min (GPM) 5302 (gal*ft)/(min*kW)


To find the actual power you will get from that moving body of water, calculate Pnet with the following changes made.

\, P_{net} = \frac{Q_{net}*H_{net}*e_{net}}{k}

Where:

  • Pnet= The net power extracted from the river, not including loss in delivery from power station to load (kW)
  • Qnet= Flow (Volume/time) - Only take a portion of the max flow (%take). For delicate streams this may be a small percentage of the total flow
    • Qnet=Qmax*%take
  • Hnet= Head (Vertical drop in feet) - This is the actual head that you have available due to losses from friction. Calculate friction loss using tables based on the materials you use for diversion (e.g. PVC)
    • Determine equivalent length of pipe by adding actual length of pipe and equivalent lengths of fittings based on tables using pipe size
    • Find Frictional Pressure Loss Ratio (FPL) coefficient in ftloss/ftpipe based upon flow rate and pipe size
    • Calculate Hloss=equivalent length of pipe * FPL
    • Hnet=Hmax-Hloss
  • enet= Efficiency of the turbine - Always between 0 and 1, usually between .5 and .9 depending on the turbine type and flow rate. A value of 0.78 is a good guess for modern turbines in average conditions
  • K=Unit conversion factor (see table above for some common values)

Note that these equations are static in time. You must run these equations with a resolution high enough to cover periods of variation (e.g. monthly river data).

Costs/Costos

The cost of a system is dependent on the location, power needs, locally available materials or components, and type of system you build. Aside from ideal site conditions, the cost-efficiency can be increased if local labor and expertise is utilized, where there are high load requirements (ideally, industry during the day and domestic needs at night), and the system uses easily maintainable and replaceable parts.[32] According to Retscreen Canada 75% of costs are site specific. [33] The typical range in cost is $1,200 to $6,000 per installed kW.

Las pruebas de la factibilidad que ejecutamos utilizaron al programa de software RETScreen para estimar el poder potencial que sería disponible de nuestro sistema prepuesto. Este programa también nos permitó a estimar los costos potenciales de la instalación del sistema y prever la cantidad del tiempo que sería necesario para que la comunidad se recupere tales costos. Éste incluye las tarifas posibles de conectar la energia renovable a la red eléctrica pagadas por la Comisión Federal de la Electricidad (CFE) a la comunidad, la venta de los créditos internacionales de las emisiones de gases invernaderos (de aquí en adelenta conocidos como créditos de carbón) en el mercado internacional, y la formación de una empresa independiente de electricidad por la comunidad que entonces vendría su electricidad al gobierno.

Site Specific Costs

The estimated up-front costs for the hydro systems designed at each location were an important part of the RetScreen analysis, they were used to determine a payback period.

Financing

Potential options for increasing the feasibility of a system include: grants, selling carbon credits based on greenhouse gases avoided by the micro hydro system, or selling the unused energy back to the local power company to receive income through feed-in tariffs.

Grants

The location of, intent of, or group assisted by the project; renwable energy generated; protection of resources; greenhouse gases avoided; or end use of the electricity can help to secure grants by different sources to assist with the initial capital required to build a system. A couple of examples of grant organizations that might be pertinent to a micro hydro project are:

for projects that combat environmental problems and protect human rights.[34]

  • Terra Viva is a "directory of international grant funding for agriculture, energy, environment, and natural resources in the developing world."[35]
Carbon Credits

Selling carbon credits on the international market is a way to increase the feasibility of this system. For every megaton of CO2 not emitted by this clean energy form a carbon credit or OCO can be sold to a company generating these greenhouse gases. This market exists because of the emissions cap created by the Kyoto Protocol. Prices vary, but 3Degrees [36]buys these credits at $15.00 (USA) per metric ton of CO2.

Feed-In Tariffs

Feed-in tariffs pay a rate for electricity fed back into the grid from a renewable energy technology such as solar, wind or hydro.  Feed-in tariffs both encourage investment in renewable energy technologies and supplement the grid with cleaner sources of power otherwise going unused by the owner of the system.[37] The Mexican government approved small-scale solar grid tie-in in 2007, but there are not yet any laws for wind or hydro power technologies. [38] [39]

Permits and Grid Tie-In Feasibility

  • Requirements to obtain a permit for construction[40]
    • Required Application
    • Copy of property payment for the year
    • Copy of owner´s identification
    • Copy of exact location and official updated number
    • Sketch of what will be constructed and a copy (architectural and with structural details, legal size or double letter size)
    • Copy of feasibility and use of site (in case of commercial use or if there is more than one occupant in the same property)
  • According to Artículo 192 from La Ley Federal de Derechos from La Constitución Política de los Estados Unidos Mexicanos, applicable fees for use of national water are $2,745.00 (MXN); for use of land within 10 meters of national water are $1,163.00 (MXN)[41]
  • According to Capítulo 3 of Artículo 80 from La Ley de Agua Nacionales from La Constitución Políica de los Estados Unidos Mexicanos,concessions are not required for small scale hydro power projects[42]

Environmental Considerations

Climate & Rainfall

The climate and amount of rainfall in a region determines the seasonal water flow in a river. A more feasible location for siting a micro hydro system has a small annual range of flows (as opposed to an area with a wide range of slows between seasons). Information on flow duration and seasonal changes affects energy calculations.[43]


Sites

River near Pueblo Molino de los Arcos

    
MolinoDeLosArcos.jpg

Date Visited: 12 July 2010
Flow rate calculated: 3015 GPM
Head:
30 feet
Length of Pipe:
110 feet
P max:
17 kW
P net:
540 Watts
GPS Coordinates: 
N 62.8º W -92.6º
Feasibility: 
The river of Peje de Oro flows through this small community, which lies within San Cristóbal de Las Casas. They currently have a micro hydro system infrastucture such as a weir, turbine house, forebay tank and part of a canal that is not in use. Federal power has been cheap enough to make the cost of repairs unjustifiable, but recently the community expressed an interest in repairing the system. Since the infrastructure is already in place the feasibility study would be on the cost of repairing the canal, replacing parts and getting the system running again.



Río de Alcanfores

    
Alcanfores.jpg

Date Visited: 17 June 2010
Flow rate calculated:
120 GPM
Head:
15 feet
Length of Pipe:
87 feet
P max: 670 Watts
P net:
220 Watts
GPS Coordinates:
N 16º44.730' W 92º38.028'
Feasibility:
This small river is close to the neighborhood of Alcanfores, outside of San Cristóbal de Las Casas. The amount of power generated by this stream during the rainy season is sufficient enough to consider the site feasible for the construction of a pico-hydro system. This stream is of interest because the community of Alcanfores is near the site surveyed, and a Zapatista community seeking independence from the government lies approximately an hour further upstream. But the amount of available head did not warrant futher investigation of the site.



Río Jataté en el Pueblo de Corralito

    
ElCorralito.jpg

Date Visited: 14 July 2010
Feasibility: This site lies a bit further from San Cristóbal de Las Casas on the way to Ocosingo and Palenque. Winding down out of the mountains, we could see that the vegetation grew more lush and the maps indicated that heading in this direction would be an ideal zone in terms of rainfall, topographic variety and community location. Corralito is a tiny farming community known for its small touristic attraction of a waterfall in the headwaters of Río Jataté, which goes on to power the Cascadas of Agua Azul. We did not take measurements of its width and depth due to lack of both time and proper introduction to the community. We did speak with a local agronomist, who informed us that the local power lines came from the CFE and we observed a billboard near the center of the community reading that it was being supported by government construction, which could prove useful as a source of grants. We also passed many signs posted outside of autonomous communities reading that they were in protest of paying high government taxes for electricity to power their lights, which may present opportunities for further investigation.

 Parque Ecología Las Canastas, San Cristóbal de Las Casas

    
LasCanastas.jpg


Date Visited: 21/23 July 2010
Flow rate calculated: 197,800 GPM
Head: 15 Feet
Length of Pipe: 80 feet
P max:
558 kW
P net: 220 Watts
GPS Coordinates: N 16º43.969' W 092º36.135'
Feasibility: This site is situated just outside of San Cristóbal de Las Casas behind the neighborhood of La Revolución. A weir and canal have already been constructed on this site for irrigation purposes. A road brings you about 100 feet from the dam. The fact that some of the infrastructure necessary for a hydro set up makes this location very promising. We spoke with a local resident who told us the river had relatively steady year-round flow. There are a few homes, a permaculture community that we learned about which may be constructed in the hills above the river and a nearby factory that may be interested in the generation of micro-hydro power. Although our RETScreen analysis did not indicate a current feasibility, more accurate river flow data, a grant or subsidy from the government for the community, or interest from the factory may be enough to change the financial circumstances.

Parque Ecoturística Arcotete, San Cristóbal 

    
ElArcotete.jpg

Date Visited: 23 July 2010
Feasibility: This river is part of an ecological park outside of San Cristóbal de Las Casas further upstream from Las Canastas along the same river. Attempting to test the flow of the river proved unsuccessful. Matt took one step into the river and immediately began sinking rapidly into the mud. Tests were discontinued for safety reasons. In addition to difficult testing conditions there did not appear to be any communities nearby. For these reasons Arcotete was ruled out as a feasible location, however should a community someday form, we can extrapolate from our word-of-mouth information on the flow data in Las Cnastas that the site maintains a strong year-round flow.



System Designs

Both systems at the two most feasible sites of Las Canastas and Molino de los Arcos are designed to be AC integrated systems. AC integrated systems bring the generated electricity directly to a user, unlike a battery system where the user must pick up a charged battery at the powerhouse. The available power is limited by the potential of the stream. If the site has enough flow and head, this system can be designed to the highest load requirement of the community. [44]

Figure 3: Image credited to: Homepower Magazine


Las Canastas

The system at Las Canastas is designed for a low head, high flow situation. We selected the Ampair UW100 Water Turbine, which is a submersible reaction turbine that gets energy from being placed directly in the river. [45] This system was designed to be grid-connected and therefore utilizes transmission wire to deliver the electricity to the consumers.


Molino de los Arcos

Molino de los Arcos has an existing micro hydro infrastructure that has been unused for a number of years, so much of the design of this system is dependent upon repairing the existing parts. Water will be diverted from the river with an approximately 1 kilometer long canal that will be constructed out of concrete and rebar. The penstock will be replaced with about 100 feet of 28" diameter pipe leading down to the turbine house. The turbine house will get a new 12kW turbine and generator. Upgrades to the transmission line system may be required as the new load may be more than when the system was originally in place.





Conclusion/Conclusión

Assumptions Used for Results/Suposiciones Usados para los Resultados

  • Yearly river flow data extrapolated from Rio Grijalva. A river in Chiapas, but not connected to Peje de Oro. Awaiting more accurate data.
  • Construction worker wages and predicted meters of canal construction in a day. Based on quotes from construction workers in town.
  • Carbon credits can be sold on the international market. International Market price from http://www.3degreesinc.com/ This price is not region specific. It will most likely vary because the value of carbon credits depends on how dirty the electricity generation is in each region.
  • Feed in tariffs for micro hydro are legal. Some sources say yes, some sources say only for solar.

Sitio Propuesto y Suposiciones

Para estimar la fiabilidad de nuestro sistema extrapolamos los valores del flujo de todo el año del río con datos del cercano Río Grijalva. Hemos inidicado el trámite de obtener datos más específicos del río Peje de Oro que fluye por Molino de Los Arcos. También estimamos nuestros costos laborales del sueldo de obreros locales de la construcción y cálculos aproximados de la eficiencia del trabajo obtenidos de las conversaciones con trabajadores y albañiles locales. Los precios de los créditos carbonos que utilizamos fueron obtenidos de los precios corrientes en el mercado internacional y no son específicos para la región. Encontramos información contradictoria sobre la legalidad de las tarifas para conectarse a la red eléctrica en México para el poder micro-hidroeléctrico, pero está legal conectarse directamente a la red eléctrica para los productores de la energia solar y ellos reciben tarifas.

Feasibility Study Results/Resultados del Estudio de Factibilidad

For this study Team Micro Hydro utilized/RetScreen, free software provided by Canada to evaluate renewable energy projects internationally. We inputted our projects infrastructure costs, various estimated feed-in tariffs based on CFE (Comisión Federal de Electricidad) electricity prices, the going rate for carbon credits on the international market and projected annual maintenance fees. The program then calculates based on the kW of the system when the system will pay for itself. This is where the feasibility study becomes less accurate based on the time constraints of the project. The governmental organizations could not get back to us in time with specific year round hydrological data for our specific site, therefore data for a substitute Chiapas river was used to extrapolate year round flow for Peje de Oro. The river was Río Grijalva and the data can be viewed in this pdf [46].The extrapolated data based on this source for Río Peje de Oro can be viewed in this excel spreadsheet. File:Hydrodata.xls

The following results are for the two sites we studied most intensively: Las Canastas and Molino de Los Arcos. The three graphs for each are based on the potential feed in rates. The first graph indicates the going electricity rate for region 1 minus ten percent for administrative fees, and includes profits from GHG emissions credits. The second shows the tariff as if the community formed it's own power company and gave a thirty percent discount based on CFE electricity prices. The third displays the region 1 tariff minus a forty percent administrative fee with no GHG emissions credits. Links to the RetScreen excels for each situation can be found in each graph´s caption.

Para este estudio, el equipo de Team Micro Hydro utilizó RetScreen, un software proveido gratis por el estado de Canada para evaluar proyectos de energía renovable internacionalmente. Entramos nuestros costos de la infraestructura, varias tarifas de introducción de energía renovable a la red eléctrica basadas en los precios de la CFE (Comisión Federal de Electricidad), el precio corriente para los créditos de carbón en el mercado internacional y las cuotas previstas de mantener al sistema anualmente. Basado en las kilowatt-horas que podría generar el sistema, el programa RetScreen calcula cuando la producción de electricidad va a recuperar los costos de la instalación inicial. En este paso, el studio de la factibilidad no está muy exacto tomando en cuento los límites del tiempo del proyecto. Los ONGs (Organizaciones No-Gubernamentales) no nos podían decir antes de terminar el estudio con datos específicos de la hídrologia de la zona, entonces el flujo de los meses del año para el sitio de Peje de Oro fue estimado con datos sustituítos del otro río chiapaneco, el Río Grijalva. El data se puede ver en este pdf.[47] Los datos extrapolados se puede ver en esta hoja de cálculo. 'File:Hydrodata.xls

Los resultos siguientes son de los dos sitios en cuales enfocamos la mayoría de nuestro sitio: Las Canastas y Molino de Los Arcos. Los tres gráficos de cada uno están basados en las tarifas potenciales de energía a la red eléctrica. El gráfico primero indica el precio corriente de la electricidad de región 1 menos diez porciento para las cuotas administrativas, con las ganancias de los créditos de carbón incluso. El segundo se muestra la tárifa como si la comunidad hubiera formado su empresa propia de electricidad y hubiera dado un descuento de treinta porciento basado en el precio de la electricidad de la CFE. El tercero usa la tarifa de región 1 menos cuarenta porciento para las cuotas administrativas, sin los créditos de carbón. Enlaces a las hojas de cálculo para cada situación hipotética se puede encontar en el pie de cada gráfico.

Las Canastas

Molino de los Arcos



As we can see from the graphs the cost-benefits ratio of this particular system at Las Canastas is never favorable. We advise against pursuing a micro hydro system at Las Canastas. At Molino de Los Arcos we have found a more promising cost-benefit ratio estimate. The pay back period for the best case scenario is about 18 years. In the second case it is about 22 years. In the third and worse case scenario it is about 25 years.

Como se puede ver en los gráficos la relación costo/beneficio de este sistema específico en Las Canastas nunca favorece. Aconsejamos que no se persiga un sistema de microhídro en Las Canastas. En Molino de Los Arcos encontramos una relación costo/beneficio presupuesta que se luzca más prometedor. El tiempo necesario para recuperar los costos para el caso mejor es aproximadamente 18 años. En el caso segundo es aproximadmente 22 años. En el caso tercero y peor es aproximademnte 25 años.

Suggestions

Technical Vocabulary of Renewable Energies in English-Spanish and Spanish-English

Next Steps and Lessons Learned/Próximos Pasos y Lecciones Aprendidas 

The next steps for this project are to wait for the more specific and accurate hydrological data to be delivered from the National Water Comission (CONAGUA). With this data a more accurate feasibility study can be completed. Also, the method we researched for fixing the canal (cement and rebar) made the pay back period long. We suggest researching different methods to build the canal. We also suggest using this study to try to secure grants for the system.

A big cultural lesson we learned from this project is that it can be difficult to obtain technical data in Mexico if one cannot receive it in person. Nearly all the e-mail communications between our team and Mexican bureaucrats failed to produce the necessary data. On the other hand, when we met face-to-face with local people and officials such as CONAGUA in Tuxtla Gutierrez we found the people extremely helpful and open.

Los próximos pasos para este proyecto incluyen esperar para los datos hidrológicos más específicos de la Comisión Nacional del Agua (ConAgua). Con esta información un estudio de la factibilidad se puede completar con más precisión. Además, el método que investigamos para reparar el canal usando cemento y rebar alargó el tiempo necesario para recuperar los costos. Aconsejamos que se investigue otros métodos para construir el canal utilizando este estudio para obtener una subvención para el sistema.

Una gran lección que aprendimos de este proyecto se qué puede ser muy difícil obtener datos técnicos en México si uno no se puede recibirlos en persona. Casi toda la comunicación por e-mail entre nuestro equipo y los burócratas Mexicanos fracasaron en producir los datos necesarios. Por el otro lado, cuando nos enfrentamos cara-a-cara con la gente local y los oficiales de ConAgua en Tuxtla Gutierrez encontramos a unas personas sumamente amables y abiertas.

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