INTRODUCTION
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.
CONCLUSION
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.
