RENEWABLE ENERGY DEVELOPMENT IN CUBA:This article was originally published in IEEE Technology and Society Magazine, Summer, 1997.
SUSTAINABILITY RESPONDS TO ECONOMIC CRISIS
National Center for Appropriate Technology,
Energy Analyst, Berkeley, CA
Energy Consultant, Denver, CO
Solar Energy International, Carbondale, CO
School of International Service,
The American University, Washington, DC
School kids play in the shade of a photovoltaic panel that powers lights in their remote village school. Down the road a few dozen kilometers, a couple of teenagers sit next to a small hydroelectric plant, listening for subtle changes and tinkering with the manual controls to keep the frequency stable as load varies. Throughout the countryside, large sugar mills pump electricity back into the national grid. In Havana, a father pedals past an empty gas station on a bicycle loaded with his son on the handlebars and his wife on the back, each carrying a large bag of groceries. These are images of a country struggling in creative ways with a serious energy crisis.
The collapse of the Soviet Union and dissolution of the socialist bloc at the end of the eighties brought an end to trading terms that had allowed Cuba to trade sugar for oil and other imports at favorable rates, an arrangement that had helped Cuba rapidly develop its economy. The U.S., still looking for ways to put an end to a socialist revolution just off Florida's coast, saw in this turn of events an opportunity to put economic pressure on the government led by Fidel Castro. In 1992 and again in 1996, the U.S. intensified the economic embargo on Cuba, making access to resources and up-to-date technologies difficult and expensive. This triggered an economic crisis - which Cubans euphemistically refer to as the "Special Period" - that has put a major strain on this previously flourishing economy. As prices of energy and other resources have skyrocketed, production in the country has plummeted. Commodities ranging from oil, soap, and foodstuffs to medical equipment like pacemakers and even basic medicine have become scarce and expensive.
Cuban annual per capita energy consumption has dropped to about four barrels of oil equivalent, half of what it was before the Special Period. By comparison, the U.S. uses the equivalent of 59 barrels of oil per person annually.
About 20 North American specialists in energy conservation and alternative sources of energy, including the authors, journeyed to Cuba in June of 1996 to learn how the Cubans are dealing with the energy aspects of this crisis. The focus of the trip was a week-long international solar energy workshop sponsored by CubaSolar, an independent association of many of Cuba's top scientists, engineers, and planners working for the development and application of alternative sources of energy in Cuba. In addition to technical sessions and visits to Cuban research labs in Santiago de Cuba, the conference provided travel opportunities to see firsthand how Cubans are implementing energy alternatives in remote sections of the country.
We found a country that is working hard to become self-sufficient in energy, putting a major effort into research, development, and demonstration of efficiency and a wide variety of indigenous renewable resource technologies, including sugar cane biomass for electricity and cooking gas, small rivers for hydroelectric power, wind and a prodigious amount of sun for electricity with photovoltaics and wind generators, and bioclimatic architecture to reduce energy needs.
BIOMASS CONVERSION: SELF SUFFICIENCY THROUGH SUGAR
Cuba's reliance on sugar exports plays a central role in its economic and energy problems. Many in the Cuban solar energy community look towards sugar as a potential centerpiece of Cuba's recovery. Imported oil has long fueled the majority of Cuba's energy needs. Sugar, the main export crop, provides the credits to get that oil. Under an agreement with the former USSR, Cuba had a stable and affordable supply by trading one ton of sugar for four tons of oil. In this respect, Cuba before the Special Period was in a situation not too different from most other sugar producers. The international free market for sugar represents only a small fraction of the total market for sugar. Most sugar is sold by contract at above-market prices, typically to the former colonial power; e.g., Jamaica sells to Britain.
With that arrangement gone, Cuba is exposed to world market prices for both its sugar exports and its oil imports. Since the collapse of its preferential trade agreement with the USSR in 1989, Cuba receives only about one ton of Russian oil for one ton of sugar.
The result has been a dangerous cycle: inadequate oil imports mean insufficient diesel to fuel harvest vehicles and other agricultural production equipment, and less feedstock to make fertilizers and pesticides. The shortages hamper the sugar harvest, reducing output. Less sugar to sell means Cuba gets even less foreign exchange and can buy less oil, completing the downward spiral. The results have been devastating, with the island's oil imports dropping from 13 million tons in 1989 to 6 million tons in 1992, and the crucial sugar harvest cut in half by 1993. (1) The reduction in oil imports has also led to widespread electric shortages as generation, which is primarily dependent upon oil-fired facilities, dropped from nearly 14 billion kwh in 1990 to only 10 billion kwh in 1994. (2)
Cuban agriculturists have responded to the fertilizer and fuel shortage (as well as the embargo-induced difficulty in obtaining pesticides) with a crash program to adopt and develop alternative agriculture methods such as minimal tilling to reduce tractor use, composting to reduce fertilizer needs, and organic pest control to reduce dependence on pesticides.
The sugar mills are a key part of the Cuban plan to compensate for the oil shortage and become energy self-sufficient. For decades, Cuba's 156 sugar mills have burned the waste cane stalks, known as bagasse, to fuel boilers and, through cogeneration, provide electricity for the mill operations. But the cogeneration systems and the sugar cane processing equipment were designed to be inefficient energy suppliers and users in order to avoid a surplus of bagasse that would have to be discarded.
Today the sugar mills generate an average of 20 kWh of electricity per ton of sugar cane in their older, less efficient steam turbines that operate at a pressure of 18 atmospheres. The conversion rate in the newer mills, built in the 1980s, is about 40 KWH per ton of cane, enough to make them net contributors to the national grid. (3) The typical conversion rate in industrialized countries is 60 to 80 kWh. In Hawaii, with the use of more efficient electricity cogeneration technology that is manufactured in many countries today, net exports of electricity to the grid already reach 100 kWh/ton, while advanced biomass-fueled cogeneration systems undergoing commercial trials worldwide might produce as much as 500 or 600 kWh per ton of cane. By storing bagasse for year-round processing and utilizing existing commercial technology to reach Hawaii's current level of mill electricity exports, Cuba could cost-effectively supply most of its electricity from sugar mill cogeneration. (4)
The sugar ministry would like to move Cuba toward self-sufficiency by installing another 100 MW of cogeneration equipment in sugar mills by the year 2000. A total of 400 MW of cogeneration potentially could be added to the grid over the next 15 years, if investments of up to $1 billion can be secured. (5) The increased output would be achieved primarily by improving the efficiency of the sugar industry so more electricity can be sent to the grid, improving the efficiency of cogeneration, and installing more capacity where the bagasse supply is not fully utilized. (6) The result would be a 10% addition to Cuba's installed electrical generation capacity, of which over 98% is from thermal plants. (2)
While financing is scarce in this embargoed island country, investment in efficiency compares favorably with the proposal to complete Cuba's Cienfuegos nuclear power plant. Construction was halted several years ago on the Soviet-designed and financed nuclear power plant. Investors are now being sought to finance completion, which is estimated to require another $1-$1.5 billion, similar to the sugar upgrade plan.
Which is the better deal? Assuming a 50% duty factor from the twin 417-MW reactors, the energy output of the nuclear plant would be about the same as from enhanced bagasse power plants. The cost to build (under current optimistic estimates for completion of the nuclear project) would also be comparable. The bagasse plants are cheaper to operate, since the fuel is an on-site resource available at no cost. The nuclear plants would create a new dependence on expensive imported nuclear fuel - and a dangerous, expensive radioactive waste disposal problem. Additionally, the cost of upgrading an outdated bagasse plant in the future is certain to be much lower than decommissioning a radiation-saturated nuclear power plant.
Sugar's potential contribution to the Cuban search for energy self-sufficiency does not end with converting cane waste into electricity. The industry produces about 3 million tons of solid "cachaza" a year - the residue of minerals and wax left after filtering the pressed cane juice. Cuban sugar researchers are developing biogas digesters to convert the cachaza into methane gas for cooking fuel. We visited a biogas plant built in 1996 to provide fuel for a workers' cafeteria at the Dos Rios sugar mill in Santiago Province. The Dos Rios plant uses one to two tons of cachaza per week to produce 23 cubic meters of methane gas each day in a 40 cubic meter digester. This is more than ample to meet all the needs of the mill cafeteria that feeds 300 to 400 people. The plant is a success, paying for itself in four months of operation. Ten similar biogas plants have been built for other industrial kitchens in the area. (7)
Cuba is also using other biomass, such as coffee bran and rice hulls, as energy sources. The country produced about 250,000 tons of rice and 55,000 tons of coffee in 1995. About 70% of the coffee bran byproduct is used in the coffee industry itself, primarily burned in the ovens. Cuba is investigating the energy conversion potential of the remnants that are available for electrical generation. (6)
HYDROELECTRICITY: MANUAL MICROHYDRO IN THE MOUNTAINS
Hydroelectricity is second only to biomass in Cuba's renewable energy picture. While Cuba has few large rivers, it has many small ones, which are well suited for microhydro generators. The hydroelectric potential in Cuba is estimated at 650 MW, with an annual generation of 1300 GWh. Cuba started utilizing hydro with a 1.7 MW grid-connected plant in 1917, but to date, Cuba has exploited only 55 MW of the potential, with annual generation of 80 GWh. The capacity factors are somewhat low due to the seasonal fluctuations of the rivers, as well as the requirements for irrigation use of water at certain times of the year.
Over half of this total potential could be realized through the 360 MW Toa-Duaba project in eastern Cuba. An estimated 600 GWh could be generated per year from the Toa river, while harnessing the smaller rivers above the Toa could add an additional 120 MW of capacity, generating 300 GWh per year. This project is considered a priority in the National Energy Plan, but, as with all other energy projects, lack of financing has slowed its realization. (8,9)
Microhydro generators already provide electricity to some rural villages in Cuba's mountainous regions. The microhydro potential in Cuba is estimated at 25 MW, spread out over more than 400 sites. About 200 of these microhydro sites have been developed already, supplying 30,000 Cubans with electricity. Four per cent of the Cuban population (160,000 homes) is still without electricity. (10)
We visited one 30-kW (peak) microhydro station at La Bruja, outside of Santiago de Cuba. The system provides electricity for 56 households in the village; the entire community uses only 10 kW. (11) Each house is limited to 100 watts, due to seasonally fluctuating river flow and to preserve capacity for a neighboring town 4 km. away. When funding is secured for a transformer, the remaining electricity will be transmitted to the nearby village. As with each of the microhydro plants we visited, the water flow is manually regulated by operators working around the clock. Again, financing is the roadblock to automatic regulation.
PHOTOVOLTAICS: BRINGING MEDICINE TO THE PEOPLE
Blessed with high solar radiation (over 5 kWh/square meter/day throughout the year, comparable to southern Arizona), Cuba has embarked on an ambitious rural photovoltaics program to bring electricity to the unserved parts of the population. The program is supported by the Cuban government, non-governmental organizations, and aid from Switzerland, Spain, Austria, Germany and India. The primary beneficiaries have been doctor's offices, rural homes, and small communities. Over 50 community clinics and 295 homes have been electrified with photovoltaics. (12)
The typical PV system on a rural house uses two 40-watt PV panels and a 150 amp-hour battery to provide power for five 20-watt fluorescent lights, a radio and a television, at a cost of $1000, or $12.50 per peak watt. Average system costs in the U.S. are $18-20 per peak watt, installed. (10,12)
As part of its national health care program, Cuba provides a medical clinic with live-in doctor and nurse for every remote Cuban village. Together they play an important role in education and preventative medicine in the community and have helped give Cuba some of the best health statistics in the Caribbean and Latin America - including a doctor-to-patient ratio twice that of the U.S. and an infant mortality rate far lower than many U.S. cities.
Of these clinics, 700 are in off-grid communities throughout Cuba, including 300 clinics with no electricity at all. Top priority is being given to providing such clinics with electricity. Over fifty had been electrified with photovoltaics by mid-1996, and the Cubans planned to double that number over the next year. (10,12)
The basic clinic system uses four 40-watt PV panels and a 250 amp-hour battery to provide power for medical equipment, fourteen 20-watt fluorescent lights, a radio, and a television. The Cubans are now installing some systems with double the capacity in order to replace the kerosene-powered vaccine refrigerator with a 12-volt D.C. refrigerator. (10,12)
With help from the Indian government, Cuba has completely powered the small town of La Magdalena (population 574) with photovoltaic modules. Each house has its own 70-watt PV system, powering compact fluorescent D.C. lights, a radio, and a television. The houses are each allocated up to 18 light fixture-hours per day. (For example, three hours of light from each of six fixtures.) PV-powered street lights, with two compact 11-watt fluorescent bulbs in each, line the main street of the village. A 3-kW PV-powered water pumping system provides 30,000 gallons of well water per day for the entire community. The community center has an inverter to run A.C. appliances, and the doctor's office has a larger eight-panel system with a PV-powered vaccine refrigerator. (13)
Cuba's Institute for Solar Energy Research (CIES) in Santiago de Cuba has scrutinized the PV installations carefully. While the installations largely have been successful, the hot, humid Cuban climate has proved tough on some equipment not designed for tropical conditions. To optimize the performance and longevity of solar installations in tropical climates, CIES is conducting research on panels, charge controllers, and invertors, in conjunction with Cuba's developing PV industry. In addition to manufacturing many of its charge controllers and some of its invertors, Cuba is assembling modules from imported cells and hopes soon to manufacture its own cells as well.
WIND POWER: A GROWING FORCE
The use of wind power in Cuba is extensive, with more than 6500 windmills for mechanical water pumping currently operating (and another 2500 installed but awaiting repairs), along with many small wind turbines (less than 1 kW) for electricity generation. Before 1990, five Cuban factories had the potential to produce 2000 wind pumping systems annually, but due to lack of funding and materials, only two factories operated in 1996, producing 250 systems. Prior to an expansion of the national grid starting in the 1960s, several hundred wind battery chargers operated in remote sites, mainly on the northern coast of the eastern provinces. The grid expansion, combined with the availability of diesel generator and cheap fuel, reduced the use of wind power for electrical generation and water pumping. Starting in the late 1980s, CIES and other research organizations began to develop small wind turbines and windmills to meet specific needs, particularly in farming and cattle ranching. In 1991, the National Energy Commission, with aid from Mexican partners, sponsored the formation of the Wind Power Group, which later established a preliminary Wind Power Program presently focusing on three areas - wind power assessment, wind electricity generation, and wind water pumping.
Until recently, the Cuban wind resource was not considered great enough to support large wind turbines or wind farms. However, with help from Mexico, CIES researchers have begun monitoring at 17 sites over the last three years. In the central and eastern parts of the northern coast, CIES has located sites that could support wind turbines as large as 150 kW. (14)
With financial assistance from Spanish non-governmental organizations and the European Community, Cuba is scheduled to begin construction of a one-MW demonstration grid-connected wind farm in 1997 in Ciego de Avila province, on the north coast. A German partnership is also proposing a wind-diesel hybrid system for a tourist hotel. The hotel will have other energy features, including load prioritization, solar water heating, and occupancy sensors for room lights and air conditioning. (15)
BIOCLIMATIC ARCHITECTURE and ECOTOURISM: DESIGNING FOR THE ENVIRONMENT
We met a number of Cuban architects who are trying to radically reduce the energy requirements and other environmental impacts of new projects through bioclimatic architecture design principles and use of local materials. Projects range from the use of natural ventilation to avoid dependence on energy-intensive mechanical cooling systems, to incorporation of straw bale construction to reduce the use of energy-intensive concrete.
These architects face challenges in convincing builders and government officials that appropriate architectural design can help solve energy needs, but they are busy researching and seeking opportunities for energy efficient and environmentally sensitive design and construction. They hope to reduce building loads to the point that renewable energy can provide all the remaining energy needs for the building.
Other techniques they are studying include daylighting, waste recycling, use of local and natural materials, minimizing non-recyclable materials, rain catchment, and construction on pylons to minimize erosion and soil compaction, while encouraging animal and plant life. (16)
In desperate need of foreign exchange, Cuba, like many Latin countries, has developed a major tourism industry catering to over a million Canadian, European and South American visitors each year. Despite an emphasis on "ecotourism," the resulting hotels sometimes have been associated with deterioration of sensitive areas, destruction and alteration of natural habitats, introduction of non-native species, and water, air, and noise pollution.
Cuban bioclimatic architects are trying to create a vision of ecotourism that is more sustainable, with hotels built in harmony with nature to minimize environmental impact. The first such example, in Pinar del Rio, was designed with natural ventilation rather than air conditioning, and with solar water heating.
The government is currently establishing environmental guidelines for development of the Archipielago de Sabana off the north coast of central Cuba. The guidelines include protection of biodiversity, location of tourism zones, and creation of a system of control and vigilance over environmental issues. Bioclimatic architects are working to include architectural guidelines within these broader environmental guidelines. Others are working on recommended guidelines for bioclimatic architecture for all tourism developments. They hope that one day these guidelines will become codes or standards, not merely recommendations.
Despite severe hardships posed by the U.S. embargo and the general economic crisis - such as antiquated computers, a primitive phone system, and shortages of everything from sophisticated lab equipment to pencils - Cuba has mobilized a major educational and research effort to bring renewables to bear on its energy needs, and made impressive technical progress toward a self-sufficient renewable energy future.
This crisis has provided Cuba the incentive to change the way it makes and uses energy, in ways that the U.S. has forgotten as the oil crises of the '70s recede in our collective memory. Starting with hands-on energy education in the high schools, Cuba is training a new generation to understand and implement sustainable, environmentally sound energy sources. It has reached out to learn about the best research in the world on renewable energy technologies with application in Cuba.
The present obstacles to the transition are not technological but economic - finding the financial resources to make the long-term investments to accomplish the energy transformation, while still meeting the daily need to buy food and medicines to keep the Cuban population fed and healthy.
Global Exchange, a U.S. group that organized the authors' visit to Cuba, is mobilizing efforts to help Cuba's energy professionals continue their work in renewable energy, energy conservation, and bioclimatic architecture. It has received a formal request from the Cuban Institute for Industry and Energy to collect computers and modems for the network of energy researchers across the island. Computers, modems, printers, renewable energy technologies (e.g., PV panels, wind turbines, etc.), architectural supplies, and money to purchase these items are being collected. To make any of these donations, please contact Global Exchange at 2017 Mission Street, Suite 303, San Francisco, CA 94110. E-mail: email@example.com. Web site: http://www.globalexchange.org/country/cuba
(1) Unless otherwise noted, data contained herein are from unpublished scientific papers distributed in Cuba.
(2) U.S. Energy Information Administration, Office of Markets and End Use.
(3) Emir Madruga, Vice President, CubaSolar, oral presentation at CubaSolar "Solar 96" Conference, June, 1996.
(4) Eric D. Larson, Princeton University, "The Potential for Sugarcane-Based Electric Power in Cuba". Unpublished paper, 1994. Larson notes that an advanced cogeneration technology, the biomass integrated-gasifier/gas turbine combined cycle, promises to nearly double the electricity export potential of sugar before the turn of the century.
(5) Authors' interview with Jaime Santiago, Director of sugar cane research station near Central Dos Rios sugar mill, June, 1996.
(6) Authors' interview with Eliseo Galivan, vice president for communication, CubaSolar; he is also an official of the Cuban Energy Ministry. January, 1997.
(7) Authors' interview with biogas plant manager at industrial kitchen, Central Dos Rios, June, 1996.
(8) Luis Berriz and Emir Madruga, CubaSolar, "Cuba and Renewable Energy." Unpublished paper, 1996.
(9) Comision Nacional de Energia, "Programa de Desarollo de las Fuentes Nacionales de Energia," Habana, Cuba, June, 1993.
(10) R. Ramos, et al, "La Energia Fotovoltaica: Una Opcion a la Electrificacion Rural en Cuba," in Energia Regenerativa y Desarrollo. Habana, August, 1995, pp. 23-27.
(11) Juanita Darling, "Global Power Plays Help to Light Up Villages in Cuba," Los Angeles Times, June 21, 1996.
(12) J.A. Alabart, M. Rodriguez, R. Ramos, I. Batista, Yoel Moreira, Soe del C. Marquez, Centro de Investigaciones de Energia Solar, Santiago de Cuba. "Las Energias alternas: Una Opcion para El Desarrollo del Programa de Electrificacion Rural en Cuba." Unpublished paper, 1996.
(13) Authors' interviews conducted during site visit at La Magdelena, Cuba, June, 1996.
(14) CubaSolar, "Resumen Comparativo de Resultados de las Mediciones Entre las Mejores Estaciones en 1994 y 1995." Habana, August, 1995.
(15) CubaSolar, "Cuban Wind Power Program." Informational manual provided by CubaSolar. Habana, 1995.
(16) Gisela Diaz Quintero, "Turismo Ecologico." Unpublished paper, presented at CubaSolar Conference, Santiago de Cuba, 1996.
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