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In terms of pollution avoided, a 5MW small hydro plant typically replaces 1400 tonnes of fossil fuel annually, avoiding the emission of 16,000 tonnes of CO2 and over 100 tonnes of SO2, while supplying the electricity needs of over 5,000 families. Moreover, small hydropower has a huge, as yet untapped potential in most parts of the world, and can make a significant contribution to future energy needs. It depends largely on already proven and developed technologies, yet there is considerable scope for development and optimization of them.

Small Hydropower in Jamaica
Jamaica neither has the volume of running water in its various rivers or the finances to construct a large or medium size hydropower plant. It, however, has a number of small hydro plants (a total of 24MW) in operation now, and has been using hydropower technology for nearly 100 years. For the future it is expected that private sector entities will find it favourable to install other small hydropower generating facilities especially since the PCJ has formally estimated that there is potential for another 94MW capacity.

JPSCo at present uses the 24 MW of small hydropower as part of its base load capacity. Most of the plants, however, are fairly old and are at present undergoing rehabilitation; the oldest having been commissioned in 1945. Another constraint is the fact that all of them are run-of-the-river facilities, which as a result, guarantees good production in the rainy seasons when the associated rivers are almost in spate, and poor production when water levels are low and flow rates are slow due to drought, an almost yearly occurrence in Jamaica.

Additional Small Hydropower Capacity Projected for Jamaica

Source: PCJ (1999)

BIOENERGY
Bioenergy is energy derived from organic matter that includes Biomass, which are trees and vegetation, and their waste matter on the one hand, and animal waste and their main gaseous derivative, Biogas, on the other hand.

Biomass Technology
The stock of any country's biomass resources at any given time is its reserves of unprocessed growing plants, whether they be agricultural crops, forests or wild grasses and weeds; and processed organic materials, namely solid waste arising from human consumption.

Energy produced from biomass are classified as:
(1) Biopower - resulting from the combustion of vegetable matter by burning. Typically the burning of biomass produces heat that is used by boilers to produce steam which in turn generates electricity in similar fashion to coal generated electricity.

Although it can be argued that coal is fossilized biomass, it is categorized separately (as a conventional source of energy) because the process of fossilization which involves tremendous heating and compression, renders it fertile with compounds of mainly sulphur and mercury, which on burning releases noxious related gases that are largely absent when biomass is burned.
 

(2) Biofuels - resulting from the conversion of starchy biomass feedstock such as corn, potato and beet, to liquid fuels such as ethanol. The general process involves the fermentation of the starchy materials in a similar manner to the production of alcoholic beverages where yeast at elevated temperatures is used to break down complex sugars into simpler alcohols.

(3) Biochemicals - resulting from the conversion of biomass into chemicals which are subsequently used to generate electricity. The main chemical involved is Phenol, which is used either as a gasoline additive or burned as petroleum to generate electricity. Phenol is extracted from the liquid oil that results from pyrolysis, a process that involves the burning of biomass in the absence of Oxygen.

Some other benefits of biomass energy are:

• Significant employment of labour for planting trees, maintaining (thinning) and reaping forests and other sources of biomass.
• Increased planting and growth of trees, which leads to increased production of Oxygen (O2) and consequently better air quality.
• Replacement of conventional energy sources, which in the case of Jamaica and similar countries that have to import all their conventional energy sources, will save foreign exchange and make the country more capable of paying its energy bills.
• Reduction of the incidence of acid rain. Since biomass burning results in little or no discharge of sulphur gases to the atmosphere, unlike with conventional fuels, the possibility of acid rain affecting water bodies is significantly reduced.
• Reduction of the possibility of soil erosion and slope degradation. Wide scale planting of trees results in the stabilizing of usually unstable soils by plant roots.
• Increased rainfall and better wildlife protection. At present Jamaica is experiencing long periods of drought which impacts negatively on agricultural production, and it is believed that this is partly due to unplanned cutting down of forests without replanting. If biomass is grown for energy production where reaping and planting become simultaneous exercises, watersheds would always be adequately protected and rainfall would be steady.

Bioenergy production and use from biomass in Jamaica
The main areas of importance are bagasse, charcoal and fuelwood use.

One of the country's most notable uses of biomass is the burning of bagasse, the residue from sugar cane juice extraction. In a typical sugar factory, bagasse is burnt in furnaces that supply heat to boilers for steam production. The steam produced is subsequently channeled in different directions to operate equipment that grinds cane, operate turbines that produce electricity, and operate distilling equipment.

Many of the sugar factories use most of the bagasse they generate in the juice extraction process, but where there are surpluses, the sugar industry has planned future alternative uses for it, in an effort to reduce the volume of waste products that have to be disposed of.

Over the past several years, the MME has reported in its Annual Report that the use of bagasse in Jamaica is consistently in the region of 1.2 million barrels fuel oil equivalent (bfoe).

The other areas of biomass production and use involve charcoal and fuelwood. Charcoal use is reported to be consistently in the range 210,000 - 250,000 bfoe; and that for fuelwood in the range 550,000 - 600,000 bfoe, per year throughout the decade of the 1990s. It means therefore, that there have been no real new breakthroughs in the use of biomass in Jamaica in recent years.

The KSAC and the MME have looked at the possibility of using most of the solid waste generated in the corporate area to generate electricity. It was reported in the MME's Annual Report (1995), that at least one 5MW plant was considered, to be located somewhere on the Spanish Town road. This plant at the time was estimated to cost between US$73 million to US$26 million, a rather wide range; and the cost to produce power was estimated at US$0.12 to US$0.14 per kWh, which would be unattractive to any utility company.

 

Biogas Technology
The Scientific Research Council (SRC) is credited with being the first and most persistent custodian of biogas technology in Jamaica, having commenced research and development activities in this subject area in 1978.

Over 150 Biogas units have been produces in Jamaica from joint projects betreen the MME and the SRC.


The Integrated Waste Management Project
Since 1993, the SRC has combined with OLADE and GTZ, which provided both financial and human capacity, to expand and modernize the programme. Renamed the Integrated Waste Management Project, the erstwhile biogas programme in its new format, includes in addition to the treatment of animal waste, treatment of a wide range of organic wastes including: plant waste, garbage, human excrement, sludge, domestic sewerage and liquid waste from meat processing operations; by large quantities of microbes of different function. This treatment takes place in the gas-tight biodigester unit and results in the production of biogas plus a nutritious residual sludge. The fermentation process that takes place in the digester does so in the mesophilic temperature range of 20- 350C.

The BST is installed underground as a cylindrical tank constructed of concrete block and steel plus a comparatively high proportion of cement mortar. A number of these units have been installed annd continue to be installed in communities across Jamaica.

Local Use of Biogas
The biogas produced in any of these biodigester systems consist of approximately: 60% methane (CH4) and 40% Carbon Dioxide (CO2). It also contains small amounts of other substances, including up to 1% Hydrogen Sulphide (H2S) and moisture. These are easily removed by special filters.

Biogas is lighter than air and has an ignition temperature of about 700oC, and the temperature of a typical biogas flame is 870oC. Comparatively, the ignition temperature of Diesel oil is 350oC and that of propane is 500oC. Its calorific value is 6kW/m3, which corresponds to 1 litre of diesel oil.

A number of Jamaicans who have biodigester units are at present using biogas to replace conventional sources of energy particularly in their households. It is used for cooking (after typical burners are modified), operating refrigerators (by using a flame to induce refrigerant flow), light (with modified gas lamps), and to operate water heaters. Biogas cannot be economically liquefied but otherwise it can replace LPG in most areas of application.

Novel uses of biogas include mixing with diesel oil in a special way to derive a biogas/diesel mixture that can operate engines including electrical generators. This technology is not yet in use in Jamaica but it is estimated that for the operation of a 1 kW generator for one hour, 700 litres of biogas would be required along with an unspecified amount of diesel oil. For a simpler utilitarian engine rated at 1 brakes horsepower (BHP), the biogas requirement would be 420 litres per hour.

The following are benefits of BST technology:

• A BST supplies energy for use in cooking, refrigeration, lighting, heating and in diesel engines.
• It improves hygiene and protects the environment by removing waste organic matter and harmful pathogens.
• It provides a nutrient rich effluent that can be used for fertilizaion of agricultural crops.
• It provides treated water that helps to recharge the aquifers.
• Its replacement of conventional energy leads to savings in foreign exchange spending to the country.
• Its presence decreases the need for charcoaling, which normally leads to deforestation.
• It leads to a reduction of the energy and water bills of ordinary Jamaican citizens.
• It contributes to finding a solution to the country's municipal waste problem.

Schematic of SRC's Biodigester (BST) Unit

OTEC Energy
It has been proven for many years that as long as the temperature between the warm surface water and the cold deep waters of the ocean differs by approximately 200C (estimated to be 220C in Jamaica), an OTEC system can be employed to produce a significant amount of power. In addition, apart from power generation, OTEC systems can have positive spin-offs, depending on the process used, such as (1) desalinated water that can be used as a source of potable water and for mariculture, and (2) very cold water that can be used for refrigeration and air conditioning.

Three types of OTEC systems are known to generate electricity: (a) closed- cycle, (b) open-cycle and (c) hybrid cycle systems. In addition, versions of these systems work best if located on land or near to shore, on platforms attached to the ocean shelf, or on moorings or free-floating facilities in deep ocean waters. OTEC technology becomes more practical in an environment where the distance between the ocean's surface and where cold water of the order of 60C is located; is relatively short. In this regard, a distance less than 1,000 metres is usually acceptable.

OTEC Technology in Jamaica.
None of the local Research and Development organizations or Universities have seriously explored OTEC technology in Jamaica. However, in 1993, the Rockefeller Foundation provided Jamaica with US$95,000 to undertake planning work towards the development of a 2MW open-cycle project.

The work done so far involves the selection of a possible location site near Discovery Bay, but little other information is available.

UWICED has stated that site studies have indicated that such a project could be sited in either Jamaica or Barbados, but it is not clear if either country is prepared to put up backing funds to make the project a reality. It is also suggested that the International Finance Corporation (IFC) and the Global Environmental Facility (GEF) have been approached for supporting funds.

The possibility of establishing such a project in the Caribbean is based on the fact that (1) sites are available with the desired temperature differential (2) the region falls within the prescribed best latitude range of 200 North or South of the equator, and (3) fairly flat ocean seafloor in several locations.

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