- Landfill. This is the most practiced method in the world. More often, landfills are old mining areas and abandoned quarries. It is considered to be the most cost effective way of disposing waste. The wastes are layered into thin spreads, compacted then covered with a layer of earth and more layers are added over time.
- Integrated disposal. Primarily used for municipal waste. The process involves the minimizing of the materials, separating and collecting, then reusing and recycling non organic segment. Organic materials are used for energy and fertilizer.
- Incineration. Sometimes referred to as ‘thermal treatment’, this method involves burning of the trash. This method is used to transform waste into gas, steam, heat and ash.
- Water decomposition. The process involves the removal of the organic materials and decomposes them at high temperature and pressure.
- Recycling. This means taking some of the waste materials and transforming them into new useful products.
- Plasma gasification. This consists of heating the disposed waste to over 10,000 degrees converting these wastes into
Cogeneration sometimes referred to as CHP (Combined Heat and Power) or energy recycling is an efficient and cost-effective method of capturing heat lost during the production of electricity and converting it into thermal energy because energy that would be otherwise disposed as waste heat would be put to good use. Thomas Edison probably was the first to make use of cogeneration or energy recycling in 1882. His Pearl Street Station was the world’s first commercial power plant producing both electricity and thermal energy while using waste heat to warm neighboring buildings. Because of energy recycling, Edison’s plant was able to achieve 50% efficiency.
Cogeneration Benefits Cogeneration systems are up to 80% more efficient than that of the traditional power plants, which is normally around 30%. These gains of efficiency result in cost savings, as less fuel is needed to be consumed to produce the same amount of useful energy. In addition, results of cogeneration also include reduced air pollution, reduced greenhouse gas emissions, increased power reliability and reduced grid congestion.
Today, Con Edison operates seven cogeneration plants to approximately 100,000 buildings in Manhattan, the largest steam district in the U.S. The steam distribution system is the reason for the steaming manholes often seen in New York City. The European Union generates 11% of its electricity using cogeneration and energy savings in Member States ranges between 2% to 60%. Europe has the three countries with the worlds’ most intensive cogeneration economies, which are Denmark, the Netherlands and Finland. In response to the growing energy need, the US Department of Energy maintains an aggressive goal of cogeneration or CHP to comprise 20% of the US generation capacity by the year 2030.
Typical Methods of Cogeneration Include Gas Turbines, which are essentially jet engines that drive turbo generators. Multi-stage heat recovery steam generators use heat to produce steam and even hot water as the exhaust gradually loses its temperature.
Diesel Engines are very similar to the gas turbine. The diesel drives a generator for economical electricity production and then the hot exhaust can produce steam to drive another electrical generator or to provide heat for process operations as either steam or hot water.
In either case, the main goal in either case is to effectively extract every BTU of heat that would exceed normal atmospheric temperature in the final effluent stream of gas and cause it to produce electricity or usable heat such as hot water.
Other Forms of Cogeneration Landfill Gas Cogeneration is a great solution because the emissions of a damaging pollutant are avoided and electricity can be generated from a free fuel. Landfill gas contains approximately 50% methane andhas a heat content of about half the value of natural gas. Capturing LFG reduces greenhouse gases while contributing to energy independence and economic benefits.
Waste to Energy Cogeneration is an excellent energy model. A waste to energy plant has
been launched in Lahti, Finland. It converts municipal waste into heat and power through the large-scale use of waste gasification, gas cleaning and high-efficiency combustion. It has a capacity of 250,000 tons of waste per year and can generate 90 MW of heat and 50 MW of electricity. This system will partially replace a coal-fired plant and will make a substantial reduction of landfill disposal in the region.
Cogeneration in Jamaica The country’s only utility company on the Island of Jamaica is already using cogeneration on a small scale. The electric company plans to use this method of energy source especially in the sugar, manufacturing and tourism industries. In addition, the country also uses solar powered streetlights in the 14 parishes. Jamaica has one operating wind turbine contributing to the grid and uses bio mass energy to primarily burn bagasses to produce steam in the sugar industry.
In this world of increasing energy requirements, cogeneration whether by diesel, gas turbines, landfill gas and waste to energy can only be a good solution not only in the United States, the European Union, but also in Small Island Developing States such as Jamaica and Haiti. Officials in Haiti might ought to take a good look at the potential of waste to energy cogeneration for its most pressing needs of both power generation and of excessive municipal waste.
Photo Credit: ell brown