Garbage and Refuse Disposal, the collection and dumping or destruction of food waste and other discarded material. The proper disposal of such wastes is important because they contain matter that can decompose quickly and create unsanitary conditions. In urban areas, the wastes are usually picked up at least once a week for disposal. In some cities this service is operated by private companies; in others, by a department of the city government.
The most common method of disposal is to haul garbage and refuse to a designated dumping site. In the United States, open land dumps have been banned, and the dumping site must be a landfill. At a landfill, wastes are crushed (to reduce their volume) and covered every day with a layer of earth. The layer of earth reduces odors from the site and keeps off such disease-carrying pests as flies and rats. A landfill site must be carefully chosen so that drainage from the landfill will not pollute water supplies.
Another common method of disposal is to burn garbage and refuse in community or private incinerators. Some coastal cities dispose of wastes by dumping them at sea.
The disposal of garbage and refuse has become a serious problem in many areas. Many landfills have reached their capacity; others have been improperly maintained and have been closed for being health hazards. The use of incinerators can cause pollution of the air, and disposal at sea can cause pollution of ocean waters and beaches.
At the same time, the amount of garbage and refuse that must be disposed of continues to increase.
- Some communities have developed methods for using garbage and refuse as a fuel. The wastes are burned in specially designed furnaces to produce steam. The steam is then used either to generate electricity or to provide heat for industrial processes.
- recology. Recycling, Composting and Ecology. Other communities have promoted recycling and composting as a means of reducing the volume of wastes. Recycling consists of processing discarded products to obtain materials for new products. Such products as newspapers, glass containers, and aluminum cans are very suitable for recycling.
- In the most common kind of recycling operation, products that are to be recycled are not discarded with other refuse; instead they are taken to a central collection point called a recycling center. The materials collected at the center are then sold to various manufacturers. In composting, grass clippings, leaves, and other organic matter are mixed with layers of soil to promote decomposition of the organic matter. The resulting material is used as mulch and fertilizer.
- Powering vehicles with garbage sounds as far-fetched as Mr. Fusion, but it's already being done on a small scale. Creating liquid fuel from solid garbage involves a process called gasification, where heat -- not flame -- transforms carbon-based solids into synthetic gas, which can then be distilled into ethanol, an alcohol that's already added to the gasoline supply in many states, and used in cars already on the road.
Synthetic gas, or syngas for short, can be created from a variety of feedstocks, or source materials, including:
- Fossil fuels, such as coal, oil and natural gas
- Biomass, such as wood or agricultural waste
- Municipal solid waste, aka garbage
During the fuel shortages of World War II, European vehicles were fitted to use syngas made from wood chips, and Apartheid-era South Africa used the same technology when it was under worldwide sanctions.
In other words, this stuff has been around for a very long time. Next, let's take a look at how modern garbage-based syngas is made and turned into ethanol that can be used without any modification to your car.
How Gasification Works
Combustion uses an abundance of oxygen to produce heat and light by burning. Gasification uses only a tiny amount of oxygen, which is combined with steam and cooked under intense pressure. This initiates a series of reactions that produces a gaseous mixture composed primarily of carbon monoxide and hydrogen. This syngas can be burned directly or used as a starting point to manufacture fertilizers, pure hydrogen, methane or liquid transportation fuels.
Discussions about energy independence, renewable energy and the dangers of carbon emissions have become a huge part of the political discourse in the United States. Everyone from the president to the guy holding the "no war for oil" sign at a public protest seems interested in ways to find alternatives to fossil fuels. But not all substitutes are created equal.
Some are better for the environment; some are not. Some are renewable sources of energy; some are not. Synthetic fuels, aka synfuels, are just one of the many solutions on the table for solving the developing energy crisis.
In this case, though, the term "synthetic" can be misleading. It doesn't necessarily mean the fuels are unnatural or artificial. The U.S. Energy Information Administration defines a synthetic fuel as any fuel "produced from coal, natural gas or biomass feedstocks through chemical conversion" [source: U.S. Energy Information Administration].
That conversion creates substances that are chemically the same as crude oil or processed fuels, but were synthesized through artificial means. Conventional crude oil occurs naturally in the environment, and is used to produce a variety of fuels like gasoline and diesel. Synthetic fuel feedstocks, the raw materials used to make synfuels, have to be subjected to intense chemical and physical changes to be usable as crude oil or processed fuel.
The history of synfuels goes back further than you might think, although research and development have peaked in recent years. Synfuels were first researched in Germany in the 1923, when two scientists developed a process called the Fischer-Tropsch reaction. The process, which they named for themselves, involves converting gas into liquid fuels.
While there are alternatives to the Fischer-Tropsch process, it is the most extensively tested and widely used method for creating synfuels today.
Today, with a global climate crisis looming on the horizon and power-hungry nations on the hunt for alternative energy sources, gasification is making a comeback. The Gasification Technologies Council expects world gasification capacity to grow by more than 70 percent by 2015. Much of that growth will occur in Asia, driven by rapid development in China and India. But the United States is embracing gasification, as well.
To friends in Asia it is nice to know that promise of clean energy is looming in your backyard and neighbors' garbage, waiting!