Biomass briquettes: An energy option for Jamaica
JAMAICAN officials recently noted their willingness to allow bauxite industry players to choose what energy source to power their plants — one of those options being coal.
Coal-based electricity plants are among the oldest forms of electricity generation. However, though stable, coal would provide a number of challenges; there are many by-products of coal that are harmful to our health and environment, including mercury, sulfur dioxide and particulate matter.
I propose that instead of coal, the Government should look to biomass briquettes, which, I believe, will not only help to solve Jamaica's energy problems, but do so in an environmentally friendly way.
Biomass briquettes (or bio-briquettes) are formed by compressing bio-waste, such as paper and garden waste. Compression increases its specific density and calorific value. When burnt, bio-briquettes give off more heat energy than uncompressed bio-waste, with far less air pollution.
The heat energy creates steam that will then turn turbines to generate electricity. Bio-briquettes may also be used in households as an alternative source of fuel, instead of cooking gas for example.
Types of bio-briquettes
Bio-briquettes may be created in a number of ways, but the method of creation and the type of material used dictate their characteristics. There are low- and high-density briquettes. The former requires the use of a binding agent, while the high-density types are formed under high pressure and do not require binding agents. The latter, which are preferred for industry use, are formed using either the piston press or screw press technology (see Figure 2). Screw pressed briquettes have a concentric hole that increases the surface area exposed to heat and therefore, they possess better combustion characteristics. As a result of that, they have largely been accepted as superior to piston-pressed briquettes.
Countries using bio-briquettes
There are a number of countries that have been using bio-briquette technology to assist in solving their energy problems. They include Brazil, China, India, Japan, Kenya, Malawi, Nepal, Nigeria, and Rwanda.
According to the United States Agency for International Development (USAID), the production of bio-briquettes has played a role in reducing deforestation and the depletion of soil nutrients in Rwanda.
One of the USAID-funded projects involving bio-briquetting has employed 117 full-time and 25 part-time workers. Eighty per cent of this workforce are women, most of whom were forced into prostitution after the Rwandan genocide. The rest of the workforce consists of former street boys.
The project has significantly improved the standard of living and the self-esteem of both groups as they are now able to earn an income and not be in a high-risk environment. The USAID has expanded its interest in this technology by funding similar projects in Rwanda and other countries.
The Government of India has seen the benefits of an increased workforce, cheap energy and, a reduction of agro-waste in a number of provinces. It has also recognised the growth potential of this technology and has encouraged bio-briquetting development by providing finance, training and technical assistance to entrepreneurs at many levels in an attempt to improve briquetting operations.
There has also been partnership between the Indian Institute of Technology and the University of Twente in the Netherlands for adapting the European Screw Press to be used with Indian biomass.
This has had much success by significantly decreasing the amount of energy needed to create bio-briquettes and reducing the wear of the screw gear used in the manufacturing process.
Possible sources of bio-briquettes in Jamaica
In Jamaica, bio-briquettes can be made from banana leaves, cardboard, coconut shell, corn husk, coffee husk, saw dust, sugar cane (bagasse), waste paper, and weeds.
It is important that there be proper investigation into how the most common agri-waste products compare to ensure that only briquettes having the highest energy yield are created.
Jamaica has approximately 35,000 hectares (87,500 acres) of lands involved in cane production. This supplies roughly two million tonnes of cane per annum. One of the waste products of sugar cane production is bagasse. Bagasse, if not properly managed, causes an odour nuisance and fosters the breeding of pests. Bagasse may also contribute to ground water contamination. In its current form, bagasse is used in boilers on sugar cane estates; however, briquetting bagasse would improve its energy yield and thus improve the efficiency of the boilers.
According to the National Energy-from-Waste Policy 2010-2030, Jamaica's vision concerning waste is to obtain "affordable and clean energy from waste, creating a sustainable future".
Bio-briquettes may also help to reduce the amount of waste that is disposed of in our landfills, as much of the biomass in our garbage may be used to make bio-briquettes. The National Solid Waste Management Authority delivers approximately 1.2 million tonnes of waste to our dumps annually and a large percentage of this is bio-waste.
Converting wood and other biomass into bio-briquettes would also mean less potential fuel in a landfill in the event of a fire. This reduces both the number and duration of landfill fires as smaller landfills are easier to manage. The recent fire at the Riverton landfill, which holds approximately 40 per cent of Jamaica's waste, led to fears of hazardous materials, including asbestos, being emitted into the atmosphere. Although air tests were negative for traces of asbestos, such an accident could occur in the future.
Alvin Brown is an instructor in the Department of Electrical and Computer Engineering, Faculty of Engineering at the St Augustine campus of the University of the West Indies. He can be contacted at Alvin.Brown@sta.uwi.edu.