Waste is often recycled, placed in a landfill or burned. But in several parts of the world, rubbish is literally keeping the lights on after being converted to electricity.
In the United States alone, 390 million tonnes of rubbish is generated per year, or 7 pounds per person per day, according to a joint study conducted by the Earth Engineering Center of Columbia University and BioCycle, a magazine covering composting and renewable energy. Of that rubbish, about 69 per cent is landfilled and 24 per cent is recycled and composted. The remaining 7 per cent is combusted via waste-to-energy.
With more waste management firms putting a clean-energy spin on the burning of rubbish by converting waste to electricity, "waste gasification" technologies are poised to surge.
"This is a new technological evolution of a pre-existing process: gasification," says Andy Harris, the vice president of Waste to Energy Canada (WTEC), an integrated clean and smart waste management firm based in Vancouver, British Columbia. "Waste is oxidized at a very high temperature, during a process that provides optimum conditions for clean conversion of rubbish into renewable energy."
In the US, there are currently 86 waste-to-energy facilities operating in 24 states, processing more than 97,000 tonnes of waste per day, according to the US energy recovery council (ERC). The plants provide 2,700 megawatts of clean electricity on an annual basis. That is enough electricity to power about two million homes, says the ERC.
"A lot of people are determining there's some value in their garbage and it's better to extract that value than simply burying it in a landfill," says Joey Neuhoff, the vice president of business development for Covanta, the largest provider of waste-to-energy services in North America.
The New England region has the highest number of waste-to-energy plants in the US, with 37 operating plants total. Connecticut has the highest percentage of waste being converted into energy at the rate of about 70 per cent of its non-recyclable rubbish.
"Recently, there has been an extraordinary amount of interest in waste-to-energy out of Alaska, in New York and in Santa Barbara, California," Mr Harris says.
Canada has also seen a recent push for energy from waste. "Five or six years ago, there were only four waste-to-energy plants in Canada, but now there are seven more in the developmental stages," says John Foden, the executive director of the Canadian Energy-From-Waste Coalition.
"That's 200 per cent growth in five or six years."
There has also been recent interest from island nations such as St Maarten and other parts of the Caribbean "that don't have the landfill capacity and need the electricity", Mr Neuhoff says.
More countries are turning to the practices of northern Europe, which has been a leader in the field for years. Oslo in Norway, for example, has been so successful in its endeavors it recently experienced a shortage of garbage to convert to electricity.
In Europe, there are more than 400 facilities that generate energy from waste, with northern Europe having the largest share of waste-to-energy plants, according to the ERC. For the first time, waste to energy is now powering up in another part of the region: countries of central and eastern Europe that have joined the European Union and are now facing strict waste directives issued by the European Commission.
Although these waste directives have been laid out since 2008, Poland, along with some other countries in the EU, has been slow to adapt. The fact that some of these countries have inherited a past of environmental neglect from the former Soviet Union has not helped matters.
But that will change next month, when Polish municipalities will no longer own their waste management facilities, putting a halt to traditional landfill dumping. This change follows a new act on waste utilisation that has been applicable in Poland since last year.
WTEC, with its local partner Rank Progress, is beginning the construction of an energy-generating incineration plant in Dlugoszyn, in southern Poland, this year. The plant is expected to be fully functional by early 2015. It is the first of three planned Polish plants.
The facility in Dlugoszyn will burn 120 tonnes of waste per day and will deliver 7MW of electricity to the grid, the companies say.
Output is expected to eventually rise to 180 tonnes of waste per day through a process called batch oxidation. The plant will heat waste in large chambers and then burn the gas emitted. The heat generated from the burning gas will be used directly as heat or will be converted by transformers to generate power to the grid.
In 2011, 71 per cent of Poland's waste went to landfills. About 11 per cent was recycled, 17 per cent was composted and only 1 per cent was incinerated. The European Union average, in comparison, was 37 per cent landfilled, 38 per cent recycled or composted and 23 per cent incinerated.
Mr Harris says there is an increasing demand worldwide for waste-to-energy due to shareholder interest and public sensitivity for a clean, more sustainable approach to the disposal of waste.
To others, landfilling is an outdated approach that simply does not make sense anymore.
"Over time, it's hard to justify a high-tech, progressive, service-based community defaulting to landfills," Mr Foden says.
"Our policy is reduce, reuse, and recycle, and then whatever's left over should be managed by other technologies, such as waste-to-energy."
The benefits seem clear. For one thing, waste-to-energy eliminates additional pollution from the ongoing transport of waste via rubbish lorries across cities.
"It doesn't matter how much land you have, it's the impact of putting waste into the ground that's detrimental," says Mr. Foden.
"This involves three, sometimes four hours of travel for garbage trucks and the negative effects that has on roads and pollution."
Like any emerging technology, however, waste-to-energy raises some potential concerns.
For example, many question exactly how waste-to-energy plants prevent emissions.
According to the US environmental protection agency, for every ton of garbage processed at a waste-to-energy facility, approximately one ton of emitted carbon-dioxide equivalent in the atmosphere is dodged. This, it says, is due to the fact that rubbish burned at a waste-to-energy facility does not generate methane like it would at a landfill and electricity generated offsets greenhouse gases.
In practice, a waste-to-energy plant's flue-gas cleaning system produces very low emissions. It involves a complex set of chemical reactions that aim to neutralise and minimise the emissions, says the Confederation of European Waste-to-Energy Plants (Cewep).
During the combustion process, hot flue gases are released into the furnace and heat is transferred to water inside the boiler tubes, which produces steam for energy generation.
There has also been public concerns regarding the safety of residents living near waste-to-energy plants.
However, thanks to strict emissions limits and a host of studies by scientists and national environment agencies, Cewep says it has been proven these plants "have little or no impact on the health of their neighbours".
"Perhaps the biggest question of all," says Mr Harris, "is what happens to the ash that is left over from the gasification process?"
Unlike traditional incinerators, which are designed to burn waste and produce ash that is usually disposed of in a landfill, WTEC and other waste-to-energy facilities deploy gasification/oxidation technology.
This cleanly burns gas from waste in an enclosed system and leaves just 5 per cent or less physical material in the form of inert ash that can then be mixed with concrete, sand or cement and used for construction projects.
"The ash is completely clean, with absolutely no harm, and is virtually free of carbon," Mr Harris says.