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The earliest of the modern Danish wind turbines were composed of three propeller-like fiberglass blades that point upwind of a steel tower on which they were mounted. The latest versions, which are also manufactured by companies based in Germany, Spain, India and the USA, have aerodynamic variable-pitch blades that are as long as 40 metres in some cases, electronic variable speed drives, and sophisticated microprocessor controls.

Wind Farm in Europe

The following are typical features of the modern wind power industry:

• The largest wind turbines available today can deliver up to 2MW of electricity.
• There are nearly 14,000 MW of wind power capacity installed at present.
• Growth in wind turbine sales has averaged 40% per year for the past five years, reaching almost US$4 billion by the end of 1999. In this regard, it is said that both the installation of new capacity and cumulative capacity are approaching that of an exponential curve.
• In 1999, three countries, namely Germany, Spain and the USA accounted for about 75% of all new installations of wind power worldwide. But the nearly 500MW installed by the USA, one of the industry's leaders throughout the 1990s, was dwarfed by the nearly 1600 MW installed in Germany and the more than 900 MW installed in Spain.

Wind Power Generation in Jamaica
Wind Resource Studies

(1) In the late 1970s the first formal wind profile study was carried out in Jamaica by Dr. Anthony A. Chen of the Physics Department of the University of the West Indies (UWI). This particular study was sponsored by USAID and formed a minor part of a more substantial programme of assessment of energy resources in Jamaica at the time.

The study concentrated on wind sites pre-selected from available meteorological data and significantly, involved sites that were all located in coastal areas. Although no site with spectacularly high wind regimes was identified the data generated was nevertheless useful.

(2) The next notable study of wind conditions in Jamaica took place in the period 1990-95 when US Wind Power Inc., a subsidiary of Kennetech Corporation USA; formed an alliance with a Jamaican company and undertook a wind resource study. The study involved the installation of 90ft towers with anemometers and wind direction monitoring equipment. The data was collected on special chips with NRG dataloggers from which wind data was transferred, printed and interpreted.

(3) In the mid to late 1990s the Petroleum Corporation of Jamaica (PCJ) after forming a working alliance with Renewable Energy Systems Ltd of the UK, undertook to find possible sites with good wind regimes by driving to remote locations and inspecting the vegetation for distortions due to wind.

Commercial Wind Power Ventures
Jamaica's attempts to establish commercial wind power ventures have so far been limited to:

(a) The establishment of a single wind turbine at Munro College in St. Elizabeth in 1996, which continues to supply electricity to the JPSCo grid, and

(b) The present state of advanced negotiations between PCJ/Renewable
Energy Systems Ltd. and the JPSCo for the installation of a 20MW wind farm at Wigton in Manchester.

The Munro College Wind Turbine Project
The project was founded by and has been pursued throughout by the Past Students Association of Munro College.

Munro College is located in the parish of St. Elizabeth on one of the peaks of the Santa Cruz Mountain at an altitude of 2,500 ft. Because of its relatively flat but actually undulating terrain, it is a favourable site for capturing wind energy.

The project that culminated in the commencement of power generation in 1996, has the following features:

• The wind turbine that is at present operating is a Vestas 27- 225 kW model rated at 225kW power capacity.
• The project was funded primarily by the Environmental Foundation of Jamaica (EFJ), but also include a long list of local companies and individuals.
• The total installed cost of the facility is US$300,000. However, much of the local services, such as JPSCo's services and Alpart's crane services, were donated free of cost.

In 1997, its best year of production so far, total energy generated amounted to 527,433 kWh.

The Proposed PCJ Wind Farm
The PCJ in an alliance with Renewable Energy Systems Ltd. of the United Kingdom (UK) is to establish a wind farm at Wigton in south Manchester, to produce and sell 20MW of electricity to the JPSCo grid. The features of the project are as follows:

• Wigton is an area of about 1000-ft above sea level but is located relatively close to the south coast in the Alligator Pond area.
• The wind regime averages 8.1 m/s or nearly one m/s above that at Munro. It is also reportedly without a significant diurnal differential, which means that almost equal amounts of power will be produced in the days and nights.
• The project will utilize 23 only 900kW NEG Micon turbines, to be manufactured in Denmark.
  
   

SOLAR ENERGY TECHNOLOGY
Solar energy is energy derived directly from solar irradiation. The two main types of solar energy are (1) solar thermal and (2) solar photovoltaics

Solar Thermal Energy
Solar Thermal energy technology includes solar water heating, solar crop drying, and process heating in industry and agriculture.

Solar Water Heating
Solar water heating is by far the most popular use for solar thermal energy. It is proven technology and has been in use for many years but its use has increased significantly during the decade of the 1990s with both range and quality of products improving tremendously. The technology is now a major industry in China, Australia, Greece, Israel, and the USA.
Thermosyphon water heater systems

The most common types of solar water heaters are integrated solar pre-heaters and thermosyphon systems. A thermosyphon system relies on natural circulation of water between the collector and the tank or heat exchanger. To achieve circulation during the day and to limit reversal at night, the tank is placed above the collector.

Solar Thermal Power
Solar thermal power plants use sunlight concentrated by various types of reflecting systems as the heat input for thermal power systems. Because of their large size and preference for baseload application, most solar thermal power systems include heat storage systems, and in some cases, back-up fossil fueled power systems. Pilot plants that use this technology in the USA, currently generate about 350 MW of electricity.

Solar Crop Drying
The objective of drying an agricultural product is to reduce its moisture content to that which prevents deterioration within a period of time regarded as the safe storage time. Drying is a dual process of (1) heat transfer to the product from the heating source; and (2) mass transfer of moisture from the interior of the product to its surface and from the surface to the surrounding air. In solar drying, solar energy is used either as the sole source of the required heat or as a supplemental source, and the air flow can be generated by either forced or natural convection. The heating procedure can involve the passage of pre-heated air through the product, by directly exposing it to solar radiation or a combination of both. The major requirement is the transfer of heat to the moist product by convection and conduction from surrounding air mass at temperatures above that of the product. Or by radiation mainly from the sun plus, to an extent, surrounding hot surfaces, or conduction from heated surfaces in contact with the product.

Water starts to vapourize from the surface of the moist product when the absorbed energy has increased its temperature sufficiently for the water vapour pressure of the crop moisture to exceed the vapour pressure of the of the surrounding air. The rate of moisture replenishment to the surface by diffusion from the interior depends on the nature of the product and its moisture content. If diffusion rate is slow it becomes the limiting factor in the drying process, but if it is sufficiently rapid, the controlling factor may be the rate of evaporation at the surface. The solar absorption of the product is an important factor in direct solar drying: most agricultural materials have relatively high absorption of between 0.67 and 0.90. Heat transfer and evaporation rates must be controlled closely for an optimum combination of drying rate and acceptable final product quality. Solar energy dryers vary mainly as to the mode of utilization of the solar heat and the arrangements of their major features. The performance of natural circulation solar dryers can be compromised by very high, wet season ambient humidities.

Solar drying is a technology that has found good application worldwide but the constraints of having to depend on the availability of the sun in daytime, and no application at nights has hindered its competitiveness. This is in a market that includes very efficient gas and electric fired dryers including desiccant dehumidifiers, which use comparatively small amounts of energy. However, in countries or farming communities where electricity or domestic gases are expensive or unavailable, solar dryers have become very important.

Solar Photovoltaics (PV)
A photovoltaic generator is fundamentally different from a heat engine. Unlike heat engine derived electrical power, photovoltaics convert sunlight directly into electricity. Although photovoltaics have been known since the early nineteenth century, it was only since the early 1970s that their practical use in both the USA and the then USSR space programmes, spurred commercial interest. The operating efficiencies of today's commercial systems are less than half of that demonstrated in the laboratory, and still considerably lower than their theoretical efficiency. Two decades of field experience, since the early 1980's have demonstrated that these systems can be operated with high availability and minimal maintenance. Global shipments of solar photovoltaic cells have increased between 25% and 41% per year since the 1970s, and installed capacity has grown from 0.1 MW in 1971 to 810 MW in 1997.

The major impediment to widespread use of PV is the high cost, although there is considerable optimism about reducing the cost. The average factory price for PV modules has been reduced from almost US$90/peak watt in 1975, to around US$4 per peak watt in 2000.

In Jamaica, the two communities that are now supplied with individual stand alone PV systems by JPSCo under the DSM programme would not
have received electricity for many years if the basic criteria used by the Rural Electrification Programme were adhered to.

For PV to start competing with conventional grid electricity, however, both cell efficiency and manufacturing efficiency will have to be improved beyond where it has reached. Cell efficiency may have to exceed 30% in modules, but this may not be far off, because that level has almost been reached with laboratory samples.

 

SOLAR ENERGY IN JAMAICA

Solar radiation conditions in Jamaica
Jamaica has higher average solar irradiation than most countries in the world. A typical solar map of the entire world, which is easily available these days, will show that in the western hemisphere, only a few western states of the USA, small parts of Central and South America, and the entire Caribbean including Jamaica are classified in the category of highest average global irradiation.

The lowest monthly average radiation is 14.75 MJ/m2/day, which translates to average daily energy potentials of 4.1 Kwh/m2/day and that the maximum monthly average is about 20.20 MJ/m2/day which corresponds to average daily energy potentials of 5.61 Kwh/m2/day.

These figures are relatively high and gives the assurance that Jamaica is very suitable for widescale use of solar radiation as a primary source of energy to satisfy its growing energy needs especially since conventional energy, based on fossil fuels, which is widely used in Jamaica, is rapidly losing credibility in the world economy, because of its negative environmental effects.
   

Daily Global Radiation (MJ/m2/day), for twelve measuring Stations.

Source: A. A. Chen

 

Solar Water Heating in Jamaica
The solar water heater business in Jamaica is dominated by thermosyphon systems, which is predictable considering the warm year round climatic conditions.

Five years ago solar water heater manufacturing was a small fledging but growing business, but today the market has not continued to favour expansion of local manufacturing as an influx of reasonably priced imported ones have been providing stiff competition, but the market is still growing.

Local manufacturers include Steel Craft Ltd; Rodobar Ltd; and Econergy Engineering Ltd.

The main importers are Isratech Ltd, which are the chief importers of Israeli made solar water heaters; and Solar Dynamics, which is owned by Barbadian business persons who operate a manufacturing business with the same name in Barbados.
It is estimated that more than 5,000 solar water heater units are now installed in Jamaica, and over 2,000 were installed over the past three years: this has been boosted somewhat by the DSM programme, which has awarded contracts to a few companies (that import them) to supply hundreds of solar water heaters for its commercial and domestic DSM programmes. The improvement in sales is assumed to be a result of householders in general finding favour with these types of heaters although they are not necessarily convinced that they are a better option than electric water heaters on a purely cost basis. It is believed that like Americans, and Europeans, Jamaicans may now be prepared to pay extra for clean energy.

The local solar water heater industry is price competitive, with prices ranging from J$900 to J$1250 per US gallon. A 60 gallons electric water heater cost J$17,000 (uninstalled), and a solar water heater of equivalent capacity will cost at least J$55,000 (installed), which acknowledges the fact that in terms of initial investment, the solar heater is much more expensive. However, the companies marketing solar water heaters are in accord with the view that the payback for a solar water heater is about three years given the price of electricity in Jamaica. Since each unit is normally of service for ten to fifteen years, an investment in a solar water heater is considered prudent.

The GOJ granted the following concessions that have since been considered in unison as a waiver:

• Reductions of import duty from 30% to 5% on all renewable energy equipment.
• Zero rating for GCT purposes, meaning that no GCT, since that time, is to be paid for imports of renewable energy equipment.

Photovoltaic Technology in Jamaica

The DSM's pilot project which at present supplies PV generated electricity to two rural communities (a total of about 50 households) in separate parishes, is the largest PV project in Jamaica. In this project, each household is supplied with two modules or about 120 watts of power in individual stand alone systems that also include inverter, power conditioner, battery and accessory equipment.

PV technology is used primarily by a few companies, which have installed systems on their own commercial buildings particularly to provide lighting; and a growing number of individuals most of which are using it only because they are clean energy or specifically PV enthusiasts, in which case the decision to use PV was founded more on choice than on necessity.

The only company that is at present installing and commissioning PV systems in Jamaica is Automatic Control Ltd, with offices in Kingston and Mandeville. The company has installed all PV systems in Jamaica save for the 700-watt system at the Chemistry Department, UWI; which was installed by that institution's Electronic Unit in 1999.

Aside from the DSM project, commercial size PV installations in Jamaica include:

• The new Mutual Life Building, Old Hope Road - About 4.3k
• WAutomatic Control Engineering (Head Office/Mandeville) - 1.8kW.
• The Jamaica House lawn and security lighting - About 1kW
• The UWI Chemistry Department, Mona - About 700 watts

The only known impending commercial PV project is the expansion of the UWI system from 700 watt to 1MW to enable it to provide for all of the electricity needs of the faculty of Pure and Applied Sciences.

Solar Drying in Jamaica
The two main types of solar dryers to be found in Jamaica are (a) solar crop dryers and (b) solar timber dryers that are used in a drying process called solar seasoning.
Solar seasoning dryers have never become popular in Jamaica although the SRC attempted to introduce it to the timber industry in the 1980s. At present the local timber industry is declining as evidenced by the recent closure of the Forestry Development Company (FIDCO). This is due to the uncompetitiveness of local timber.

Heightened interest by local food processing enterprises influenced the SRC to commence its own solar drying project in 1980, which was directed at establishing the effectiveness of solar drying of crops such as banana, onion and ginger to make them more amenable to storage and transportation.

By 1983, the SRC joined forces with the UWI, and the then CAST Solar Energy Centre, to pursue a solar energy project that was sponsored by the GOJ/USAID Energy Sector Assistance Programme, to:

• Develop solar collectors and evaluate available construction materials for their thermal performance qualities
• Develop small crop drying units
• Demonstrate the application of industrial solar crop drying units
• Explore the availability of commercial bank loans to facilitate the wide scale adoption of solar crop drying in the agricultural sector.

This project was concluded by 1986 with limited success, but the overall programme continued with another collaboration with the CAST Energy Centre, to carry out shelf life studies of Pineapple that was packaged in cellophane and polyethylene bags.

The SRC has also combined forces with JAMPRO and the UTech Entrepreneurial Centre in recent years to maximize efforts to promote the use of solar crop dryers and also to encourage the formation of business enterprises that would spearhead its production and marketing.

A number of other private sector companies have developed their own versions of solar crop dryers for the local market. One of these is Econergy Engineering Ltd; which at present has its own model under test at the FTI. The Econergy solar dryer is capable of drying one pound of agro-product per cubic foot of drying space, and is also capable of achieving temperatures in the range 480C - 790C (1200 F- 1750 F) between morning and mid-day on any given day in Jamaica.
 

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