Reduce, Reuse, Recycle… Recover. As the population in large cities worldwide grows, waste management becomes an even bigger challenge. Recycling programs can divert large amounts of materials from landfills but some garbage still needs to be disposed of in landfills or Energy From Waste (EFW) sites. EFW facilities are capable of recovering energy from garbage that would otherwise be unused in landfills.
EFW and landfill gas capture systems operate on similar principles: produce steam to turn a turbine which generates electricity. The difference is the fuel used to produce the steam. Landfill gas based electricity generation relies on methane from the decomposition of organic material, while EFW facilities combust the solid waste. Both are good options as they prevent methane gas from escaping into the atmosphere. Methane has a global warming potential 72 times that of carbon dioxide. Both options sound good, so which is better? The better question is: ‘How much land and money do you have’?
The graph above relates the carbon equivalent emissions of landfills versus EFW plants. While landfills with methane capture and power production (3, above) are almost carbon neutral, it doesn’t compare to the amount of carbon emissions displaced by EFW facilities (4, above).
Some additional fuel for thought:
- For every megawatt of electricity produced by the combustion of solid waste, one megawatt of electricity possibly produced by fossil fueled is displaced. This creates a net reduction in greenhouse gasses.
- Recycling paper products is almost always better for net energy gains than burning that material in an EFW.
- For every ton of waste diverted to EFW, one less ton takes up space in a landfill. This also creates a net reduction in greenhouse gas emissions.
- One of the main arguments against EFW is that it creates a need for garbage. Building a power plant that relies on garbage can discourage people from recycling and from reducing the amount of waste they produce. Careful attention is required to properly size EFW facilities.
- Here in Durham Region, Ontario, where 53% of the curbside trash is diverted from landfills through recycling and composting programs, an EFW facility is being built as part of a plan to increase the diversion rate up to 70%. The plant will produce 17.5MW of electricity and divert 140,000 tonnes of waste. The $284 million dollar plant is scheduled for commissioning in August 2014.
- EFW is more expensive to implement and operate (roughly double to triple the disposal costs compared to landfills).
- Landfills remain an option in Ontario as land is relatively plentiful; however, public opposition to new landfills is often much more plentiful.
- Politicians have a tough time either way. EFW or landfills; there really is no winning when it comes to waste disposal. People can argue all day about which one is worse for the environment – EFW sites can produce air pollution and landfills can pollute the water table and are usually further away from city-centers leading to more truck emissions. City councils usually want the cheapest solution, and the mayor wants whatever will get him/her elected for another term, and the public – the biggest stakeholder – just wants its garbage to go away.
‘What’s a better waste disposal option – landfills or EFW’? Guess what, there is no right or wrong answer, no black and white… Only shades of gray.
This is the first in a series of blogs on energy issues written by 4th year energy systems students from the University of Ontario Institute of Technology in Oshawa, Ontario. (See blog by Dan Hoornweg introducing the series.)