Topic: Lake Atitlan Water/Power-Distribution System

Members:

  • Jeremy Black

  • Yuri Carrillo

  • Clint Sorensen



Objectives:
We first plan to assess the power that is needed to and that can be generated from pumping water from the rising lake to the surrounding villages. From our research, we will determine mechanical and electrical methods of appropriately pumping and using the water. We also plan to consider the environmental costs of such a project and research the need for such a project. Furthermore, we will research the probability of the lake rising to a level of concern.

Guatemala's Current Situation:
Approximately 51% of the Guatemalan population lives in poverty [1]. Roughly, 26% of this group lives below the poverty level, surviving with the equivalent of 1 dollar per day [2].In regards to rural Guatemala, 80% of rural Guatemalans live below the international poverty line at 2 dollars per day [2]. The high level of poverty is attributed to the unbalanced distribution of land, an increasing population, and the damages inflicted by a devastating civil war that lasted about 4 decades; the war caused the destruction of several rural communities, viable land and diminished access to basic services and resources for the people [2].Within the last two decades, the Guatemalan government and the Ministry of Energy and Mines (MEM) has sought to electrify nearly 90% of homes, despite the living concerns of the people; famine, disease, and lack of potable water are pressing and higher priority issues faced by several rural communities [2]. Though the government has commenced to electrify remote regions of the country, most Guatemalans in rural communities continue to use firewood as their main source of power [2]. Firewood prevails as the main source of energy because electricity is simply too expensive and purchasing of electronic appliances is not financially feasible. Electricity, in their view, is a luxury; experiencing a few extra hours of light during the day is not worth sacrificing a meal or exchanging another vital resource for it.
Role_of_Firewood.png
Obtained from: "Electrifying Rural Guatemala: Central Policy and Rural Reality" by Matthew J. Taylor

Another emerging issue afflicting the people of Guatemala is climate change. Climate change in the region has been associated with the escalation of large-scale weather events, including storms and hurricanes [3]. Last year, the tropical storm Agatha struck the country, killing around 180 people and damaging agricultural land and infrastructure; these losses equated to 1 billion quetzales (US $123.2 million) [3]. As quoted from the article "Climate Change Threatens Central America", written by Louisa Reynolds of the NotiCen Central American & Caribbean Affairs:
"ECLAC (Economic Commission for Latin America and the Carribbean) calculates that by 2010 in Central America, the rise in atmospheric and sea temperature, declining and unstable rainfall, rising sea levels, droughts and hurricanes will have repercussions on production, infrastructure, livelihoods and health and safety of the population, as well as weakening the environment's capacity to provide vital services and resources..."
Several communities have felt the detrimental effects of the emerging irregular weather patterns, including droughts, mudslides, floods, and rising water levels (as is the case of Lake Atitlan). The demand of water alone is expected to increase by 300% by 2050 [3]. Furthermore, climate change is prone to hinder rural development and economic advancement of the people. Farmers are loosing their harvest to the unpredicatable weather conditions, diminishing their profits and sustaining poverty in their villages. As stated by Reynolds, "Even though Central America is one of the smallest contributors of global greenhouse-gas emission in the world, ECLAC says that the region is 'extremely vulnerable to climate change as a result of its socioeconomic situation, its exposure to extreme events, and its high level of biodiversity.' Agriculture in jeapordy."

Electricity in Guatemala:
In 2008 Guatemala consumed 7.2 TWh of electricity while producing 8.6 TWh, and is projected to grow at an annual rate of 8.6%. Hydro power generation is the largest source of electricity production in Guatemala.Guatemala's energy sector was privatized in 1998, with the result of energy prices that have "increased moderately" as well as increased investment in capacity.

Electricity (GWh)
Production from:

coal
1131
oil
2322
biomass
1552
hydro
3712
Total Production
8717
Final Consumption
7175
Industry
2804
Transport
0
Residential
2407
Commercial and Public Services
1964
Values from 2008

The majority of Guatemala's electric generation is situated around Guatemala city and the southern portion of the country. Lake Atitlan is situated in between two distribution lines of the electric grid, one to the north and one to the south of the lake.

guatemala's_electricity_transport_system.png


Lake Atitlan:

Lake Atitlan (Mayan translation: the place where the rainbow gets its colors) is a large crater lake situated in the southwestern portion of Guatemala. It is situated near three volcanoes, at least one of which remains active. The surface of the lake is about 1562 meters above sea level, but has been rising in recent years. The main economy of the region relies on tourism, supported by the 281 hotels that are situated on the lake's shore. There are also a number of towns situated around the lake, as seen in the illustration below.

Note: This drawing faces south
Note: This drawing faces south


Power Generation Technologies:

Micro Hydro:

Micro hydro is used to define hydroelectric installations that generate under 100kW of power and are popular in developing countries where they can replace fuel as an energy source. It often involves diverting water away from a river via a canal or pipe, producing electricity from the water head, and then discharging the water back to the source. The cost of a standard micro hydro installation typically amounts to $1,000 - $20,000 and normally utilizes a Pelton wheel for high head low flow situations.

Pico Hydro:

Pico hydro are hydroelectric installations that deliver under 5 kW of power. Pico hydro generators are also useful in rural and remote communities that require minimal electricity. Pico hydro is a low-cost alternative for basic power generation and is potentially the lowest-cost technology for off-grid electrification.

Illustration of a Picohydro setup
Illustration of a Picohydro setup




Considerations:

Pollution:

In 2008 there was an out break of cyanobacteria in Lake Atitlan. The cyanobacteria feeds off of man made nutrients and produces toxins harmful to humans, but it is unknown whether it is spreading from increased pollution or from a temperature increase witnessed in the region. Temperature within Guatemala has been shown to be increasing from 1980 to 2010 [5]. Below are two figures, (both measured in Kelvin with MERRA "Modern Era Retrospective-analysis for Research and Applications"
Surface Skin Measurements) one of a surface skin temperature time-series of central Guatemala, and the other mapping a temperature difference of Guatelama in 1979 and 2010, showing 2010 to be warmer.

guatemalaoveryears.JPG
Surface skin temperature time-series for central Guatemala

guatemala_temp.JPG
Surface skin temperature in 1979 (on left) and 2010 (on right)


Beyond the normal concerns of environmental impact, this affects our project because of increased governmental oversight. In a plan released by the Guatemalan government, it has been recommended (unknown if enforced) that no construction occurs without environmental assessment done by MARN.

Governmental entities overseeing the pollution problem of Lake Atitlan:
  • The authority for sustainable development in the Atitlán basin and its surroundings (La Autoridad Para El Manejo Sustentable de la Cuenca de Atitlán y su Entornos AMSCLAE)
  • State Council for Nature Reserves (Consejo Nacional de Áreas Protegidas y su delegación departamental)
  • Ministry of Environment


Cyanobacteria blooming in Lake Atitlan
Cyanobacteria blooming in Lake Atitlan

Poverty:

About 74% of Lake Atitlan's inhabitants live in extreme poverty. This could affect the option of obtaining government support due to efforts in the area to increase the local education and health care system. If the construction of a hydroelectric system is seen as beneficial towards these aims, or reducing poverty in the region, it would help in any efforts to obtain financial or legal aid from the government.

NGO's operating in the area of Lake Atitlan:
  • Asociación Vivamos Mejor Guatemala




Scenarios:

The scenarios below consist of pumping water from Lake Atitlan from the city of San Lucas, located in the south eastern part of the lake. The water is to be pumped from the lake, over a ridge line, and then used to generate hydro power. This hydro power is to be sold to either the locals or the electric grid of Guatemala.

San_Lucas.jpg
San Lucas


The Advantage to choosing this location is that the water needs to be pumped only about up a vertical distance of 250 feet (~100 meters) to exit the lake basin.

Elevation_1.jpg
Elevation profile of water pumped uphill.
Elevation_2.jpg
Elevation profile of water path from the lake, over the ridge and downhill.


Model Scenario 1:

Question : Can enough water be pumped out of Lake Atitlan to stop the rising water level and generate enough hydro power to offset the project cost?

Answer: Maybe, but the scale of such a water system would be immense.

Pump System:

The lake has a surface area of about 140 square kilometers and rises about 3 meters a year. To offset this volumetric increase of water every year, a pumping system needs to be installed to handle 13 cubic meters per second (cms). Using the pump selection tool from the ITT Corporation, the most appropriate pump located was an SSF 30 x 36 pump. It can handle a flow of roughly 4 cms and produce a head of almost 50 meters. With these characteristics, we would need 4 pumps(2 parallel sets of pumps, each set having 2 pumps in series ) to achieve the flow and head desired. Each of these pumps requires 10 MW of power a piece, totaling up to a 40 MW power pumping system. My calculations indicate that these pumps are then only 20% efficient. This is very unlikely, and likely the pumps will not require that much power.

SSF_Pump_Curve.png
Pump curve for an SSF 30 x 36 pump
SSF_pump_picture.jpg
SSF 30 x 36 pump.



Piping System:

Assuming a flow velocity of one meter per second through a piping system, the pipe diameter would need to be at least 4 meters in diameter. In addition to this calculation, by using EPANET (a water system modeling software provided by the EPA) it was determined that the pipeline would need to be able to handle roughly 200 - 300 psi. A similar type of pipe as was used in the LA Aqueduct, as seen in the picture below, will need to be used in this project.



EPANET_pressure_profile.jpg
Pressure profile of water pumped to ridgeline (left to right, from lake to ridge)
LA_aquaduct.jpg
The LA Aquaduct has a pipe diamter of roughly 3.7 meters.


Power Generation System:

The theoretical power that can be extracted from water is given by the equation...
Power = Head x Mass flow x Gravity
Where Head is the drop in elevation of the water flow in meters, mass flow is mass per time flow in kilograms/second, and gravity is the acceleration due to earth gravity in meters/(second^2). The graph below demonstrates this equation in action, note the location of 13 cms on the x axis. With the high flow of this scenario there is no practical ceiling to how much power that can be generated. Subsequently a power generation capacity of 80 MW was installed.

Theoretical_Power.jpg
Theoretical power generation from water.


Financial Results:

Assuming a 5 year construction time, as well as factoring for other cost such as loan interest and operations & maintenance, the project could financially break even in about 13 years. However this is an extremely rough estimation of foreseeable cost. A project of this scale may be greatly influenced by the rural location of the area, the nature of the utility system in Guatemala, as well as the views of locals where the project is constructed.

Financial_1.jpg
Scenario 1 Financial Model.


Calculations:

The calculations for the above scenario (scenario 1) are located in the excel file below.
.



Model Scenario 2:

Question: Is it financially viable for water to be pumped out of the lake to generate electricity for the surrounding area.

Answer: Yes

Pump System:

This scenario is much smaller of scale, so a lower flow of 0.2 cms was arbitrarily chosen because it could be handled by a wide range of pumps, thereby lowering the pump cost.

Piping System:

Along with a lower flow rate comes a much smaller pipe. With a flow rate of about 0.2 cms it was calculated that a pipe with a diameter of roughly 0.5 meters will suffice for this scenerio.

Power Generation System:

An additional advantage to a lower flow rate is the ability to use micro-hydro to generate power. The main advantages of implementing a micro-hydro system in villages such as San Lucas Tolíman include [7]:
  • Its suitability for decentralized development, fully using local materials and appropriate technology, allowing the participation of local people.
  • It is a mature technology, posing as a small investment risk.
  • It has low operating costs, it is easy to maintain, and it is generally a reliable power source.
  • May introduce social benefits by empowering locals to develop micro-economies, introducing improvements in material and spiritual life for villagers.

Powering San Lucas Tolíman with Micro-Hydro:

The village of San Lucas is populated with approximately 17,000 people. In Guatemala, the average number of children per woman is 4.


children_per_woman.png

Assuming that each family unit has both parents, the average household size is about 6 people per home. With these figures, we estimate that there are roughly 3,000 homes in San Lucas.

picture.png
After some investigation and discussions with Professor Taufik, Power-Engineering Professor at Cal Poly, we estimated that the average power demand of a rural home in a developing country could be met with roughly 100W. People in rural Guatemala mainly seek electrification for luminous lighting to increase visibility in the dark as they finish the day’s tasks, i.e., preparing maize to torteár in the following morning; finishing diner as the night enters, weaving, finding items around the house, lighting to permit children to finish their homework, etc. Other uses of electricity are to power small low voltage/current devices, such as radios, small televisions, and cell-phones—a presently emerging means of communication. Another important consideration is that power consumption is also minimal due to duration of use; typically in a Guatemalan aldea (village), people go to sleep early (approximately 8:00-9:00pm). Therefore, luminous lighting is only required for a couple of hours (3-4hours). Furthermore, appliance usage is infrequent, resulting in small power consumption.



Possible Loads in Aldea home (W):

CB Radio
5
Clock Radio
1
12" TV (B&W)
20
19" TV
45-70
Cell-phone Charger
2-3

Incandescent Lightbulbs (W)
Compact Fluorescent (W)
LED Lighting (W)
40
11
1-5
60
16

75
20

100
30

Ideally, homes in San Lucas would be lighted with high efficiency LED lights.

Therefore, with approximately 3,000 homes demanding 100W each, the load demand for the entire village of San Lucas is about 300kW. According to US standards, the Load Demand of San Lucas could be met with a Micro-Hydro power generation system [7].


micro_hydro.png

Power-System Considerations for San Lucas:

The distance from the lake to the southernmost point of the village is about 1 mile (white line). The distance from the furthest points of the village (running east to west) is about 0.7 miles (blue line). If we wanted to run transmission lines across San Lucas, they would extend no more than 1 mile in length, depending on where we place our powerhouse that houses the generators. With these physical constraints, in terms of Power-System Analysis, we would model our transmission lines as Short Lines.

A Short Line Model has the following Parameters [6]:
  • Defined to be less than or equal to 50 miles (80km)
  • Shunt Capacitances may often be ignored without much error
  • Negligible losses



TL_paths.png


The following are typical Hydro-Generation Parameters [7]:
  • Efficiency of the hydraulic turbine falls within 0.8-0.9
  • Efficiency of Generator is 0.9-0.97
  • Overall efficiency of turbine-generator combination may fall in the range of 0.72-0.87


The following is a basic diagram of a power-system scheme to electrify San Lucas, given the above parameters:

power_system_diagram.png


Electronic Components found in Powerhouse:

The Battery Bank (Deep-Cycle Lead-Acid Battery Bank: 300 X 2V 8000AH):
  • Provides voltage stability to system; batteries maintain a constant voltage that can be appropriately and effectively inverted for AC transmission.
  • Provides a way to store surplus energy when more is being produced than consumed.
  • When demand increases beyond what is generated, the batteries can be used to release energy to keep household loads operating (if need be).
  • Typical Efficiency for Deep-Cycle Lead-Acid Batteries falls within 85-95%

The Charge Controller (25 x 300A):
  • Battery-based micro-hydro systems require charge controllers to prevent overcharging of the batteries.
  • Controllers generally send excess energy to a secondary (dump) load, such as air or water heaters.

Meters (Battery Monitor, Amp-Hour Meter, Watt-Hour meter): Measure display several different aspects of your micro hydro-electric system´s performance and status:
  • How full your battery bank is?
  • How much electricity your turbine is producing or has produced?
  • How much electricity is being used?

DC Disconnect: Allows the inverter to be disconnected from the batteries for service, and protects the inverter-to-battery wiring against electrical faults.

DC-AC Inverter (300 kW Pure Sine Wave Inverter): Transforms the DC electricity stored in your battery bank into AC electricity, used for transmission that is again inverted to power appliances

AC Breaker Panel: Point at which all of a home's electrical wiring meets with the provider of the electricity, whether it be the grid or a micro-hydro electric system.
power_house_components.png
With all the above considerations, to distribute about 300kW of electrical power to San Lucas, we need approximately 550kW of hydro-energy harnessed from the lake:

calculation.png


To obtain 550kW of hydro-energy, given a water flow of 0.2 cms, we need to have a head drop of roughly 280 meters between the lake and the powerhouse. This parameter is important (especially for the civil engineers on-board) to determine the geographical placement of the generator and the piping for this particular system.
calculation2.png
microhydro_setup.png

Civil Engineering Considerations:

The question of what will happen to the displaced water once it enters the village arises. In micro-hydro systems, displaced water is typically stored in a “water pond” (a small scale dam). Stored water could potentially be accessed during times of drought, when there is not enough water being supplied from the lake. Stored water could also be used to regulate power generation; water is stored during off-peak times and is discharged from the pond at peak hours. Furthermore, the displaced water could be used for irrigation, if properly filtered. A possible irrigation scheme is depicted below:


possible_irrigation_scheme.png
Image obtained from: "Innovate: Energy for the Developing World" by David Farris


Financial Results:

Assuming a 5 year construction time, as well as factoring for other cost such as loan interest and operations & maintenance, the project could financially break even in about 12 years.

Financial_Scenario_2c.jpg
Scenerio 2 Financial Model.

Calculations:

The calculations for the above scenario (scenario 2) are located in the excel file below.



*Good introduction. I expect to see a design and some calculation of costs and amount of output possible. 50% so far.* calculation of value.


Sources:
[1] http://data.worldbank.org/country/guatemala
[2] Matthew J. Taylor, "Electrifying Rural Guatemala: Central Policy and Rural Reality", Environment and Planning. Government and Policy (2005).
[3] Reynolds, Louisa. "Climate change threatens Central America." NotiCen: Central American & Caribbean Affairs 20 Jan. 2011: 2. Expanded Academic ASAP. Web. 3 May. 2011. Document URL: [[http://find.galegroup.com.ezproxy.lib.calpoly.edu/gtx/infomark.do?&contentSet=IAC-Documents&type=retrieve&tabID=T002&prodId=EAIM&docId=A247634069&source=gale&srcprod=EAIM&userGroupName=calpolyw_csu&version=1.0 ]]
The file was accessed via the Cal Poly Databases; the file is accessible via your Cal Poly Portal (see Library Services).
[4] Hirsch & Utreras, Power to the People: Hydropower, Indigenous People's Rights and Popular Resistance in Guatemala, FIVAS, September 2010 www.fivas.org
[5] Giovanni News, Goddard Earth Sciences Data and Information Services Center GES DISC, May 2011 Volume 4, Issue 1-2 http://giovanni.gsfs.nasa.gov
[6] Professor Taufik. Power System Analysis I: EE-406 Lecture Notes.(2010).
[7] Jaindong, Tong; Zhen, Naibo; Xianhuan, Wang; Hai, Jing; Huishen, Ding. Mini Hydropower. (1996)
[8] Ferris, David. "INNOVATE: ENERGY FOR THE DEVELOPING WORLD." Sierra 95.2 (2010): 69. Academic Search Elite. EBSCO. Web. 5 June 2011.
http://www.iea.org/country/n_country.asp?COUNTRY_CODE=GT
http://www.investinguatemala.org/index.php?option=com_content&task=view&id=45&Itemid=46&lang=english
http://www.csstc.org/reports/egm/P4/Presentation_Guatemala.htm
http://www.geni.org/globalenergy/library/national_energy_grid/guatemala/graphics/Ergy-Grid-Guatemala.jpg
http://www.globalnature.org/30700/CAMPAIGNS/Threatened-Lake-of-the-Year-2011/Threatened-Lake-2009/02_vorlage.asp
http://disc.sci.gsfc.nasa.gov/giovanni/additional/newsletters/giovanni-news-newsletters/giovanni_news_may_2011
http://homepower.com/basics/hydro/
Can we pump enough water to stop the lake level from continuing to rise and generate electricity to offset the project cost?