Lentis/Energy from Trash

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What is Energy from Trash?[edit]

Energy from Trash generally refers to the processes that convert municipal solid waste (MSW) into heat or electricity. MSW is made up of three parts: biomass, non-biomass combustible materials, and non-combustible materials.[1] Converting trash into electricity is a relatively simple way to offset waste production, especially when dealing with non-reusable, non-recyclable materials.

Types of Energy from Trash[edit]

There are many ways that energy can be harnessed from trash, although some are much more widely used than others.

Waste-to-Energy[edit]

The most commonly used form of energy from trash is incineration. This process is often referred to as Waste-to-Energy (WtE).

What is incineration?[edit]

Incineration turns garbage into ash, flue gas, and heat. Trash is burned at temperatures approaching 1000°C, which reduces waste mass by 80-85% and volume by 90-95%. The high temperatures can break down organic compounds, greatly simplifying the disposal of medical waste and other hazardous materials.

WtE Plants[edit]

WtE plants operate in a similar fashion to conventional coal power plants. Solid waste deemed safe to burn enters a chamber where it is incinerated at temperatures close to 1000 degrees Celsius. The heat produced from this reaction is used to heat water into steam which in turn drives a turbine to generate electricity. [2] Carbon dioxide is emitted as a byproduct during this process, but it is a far less potent greenhouse gas than the methane that would be emitted from landfills. Most landfills trap and collect emissions, but the EPA estimates that 25% of US landfill methane escapes into the atmosphere. [3]

Public Perception[edit]

Landfills[edit]

Public perception of landfills is at an all-time low, suggesting the need for new ways to manage municipal waste. Studies suggest that 65% of Palestinians understand the problems associated with landfills, but only 50% of people from Kuwait understand the negative effects.[4][5] However, those that do understand the enormity of the problem take issue with visual appearance, unwanted animals, and environmental pollutions.[4][5] Additionally, 78% of people sampled in Vancouver considered landfills the least desirable option for municipal waste management.[6]

WtE Plants[edit]

WtE plants are generally much more desirable than landfills, but not everyone is aware of what they are. What holds us back from using WtE plants is not a lack of technology, but a negative public perception or lack of knowledge. It is shown that a lack of knowledge is linked with public resistance in Vancouver; only 22% of people surveyed considered WtE facilities most desirable compared to landfills and materials recovery, because most people prefer simple recycling.[6] Moving beyond WtE's "dirty" reputation is crucial for acceptance. This stigma has and will continue to prevent expanding use of WtE technology. For example, in Austin, TX in 1984, the government could not follow through on its attempt to bring WtE to the city because of persisting public opposition; however, at the same time, Baltimore was celebrating the opening of its first WtE plant, which is still operational today without any government subsidies.[7]

Environmentalists have mixed opinions as well. Many think its good because we are generating trash anyways, and it will keep it out of landfills. However, there are other groups that are in opposition because they believe trash is not a renewable source of energy, and that it creates a dependency on garbage. A group of New York environmentalists sent a letter to the Executive Director of the U.S. Department of Energy expressing their concerns for classifying WtE as a renewable energy source, because MSW comes from mostly nonrenewable sources.[8]

Case Studies[edit]

WtE in Europe[edit]

Sweden[edit]

The Swedish Government has poured billions of dollars into subsidies and contracts for mass construction of WtE plants, which can cost anywhere from $150 million to $230 million.[9] This mass construction has caused an odd problem for Sweden: the combined capacity of waste intake of these plants now exceeds the amount of waste produced by Sweden and as a result, Sweden imports much of its needed waste from other countries. Nations exporting waste to Sweden actually pay Sweden to take in the trash but this ends up saving them money as well because like Sweden, they also have expensive landfill taxes that they are trying to avoid. [10] It is likely that Swedish officials and policy makers foresaw a waste shortage but determined that it could be used as a way to generate profit. Given the culture of government in Sweden, it is almost certain that they will continue to find ways of maximizing energy production through WtE plants.

While the Swedish Government has been actively supporting WtE, groups within the nation as well as in other parts of Northern Europe have expressed opposition. One environmental group in particular, the Zero-Wasters, has been vocally opposing WtE. [11] Zero-Wasters believe that all waste should be recycled or reused and that no form of waste should be sent to either landfills or WtE plants. Specifically regarding WtE plants, they argue that it is more practical to recycle rather than incinerate. Furthermore, they take issue with the methods by which these plants are funded. The plants are built by private companies with government contracts. Since the goal of these companies is to generate profit, they need a steady supply of waste to keep the plant running and producing revenue. Zero-Wasters argue that requiring this supply of trash reduces the need of people to recycle and is thus more wasteful both environmentally and financially. [12]

Opposition to WtE in Sweden offers interesting perspective on the dynamic between engineering, policy making, and citizenry. While engineers, scientists, and policy makers widely agree that WtE is an environmentally safer alternative to landfills, groups such as the Zero Wasters continue to fight against it, simply because they still emit carbon dioxide. Furthermore, recycling in Sweden has actually increased as more WtE plants were built, contrary to the argument of Zero-Wasters. [13] It could be contended that this disconnect is due to the fact that the Swedish Government went ahead with these plants without really getting public input and opinion while simultaneously not doing an effective job of communicating WtE science and benefits to the public.

Norway[edit]

Like Sweden, Norway has invested in WtE plants across the country. Unsurprisingly, Norway too is facing a waste shortage and has had to import trash from neighboring countries. [14] Based on first person interviews, Norwegian citizens seem more supportive of WtE than the Swedes but opposition does exist. Environmental groups in Norway make similar arguments as the Zero-Wasters in Sweden but it is unlikely that WtE in Norway will end anytime soon.

WtE in North America[edit]

There are currently 86 waste-to-energy plants in the United States, compared to 32 in Sweden. However, the population of the US is over 30 times that of Sweden, so a much smaller fraction of US trash is being incinerated. WtE plants are most common in densely populated areas where property values are high, and therefore the cost of digging new landfills is prohibitive. Northeastern states and Florida contain most of the WtE plants in the US.

US public opinion largely turned against incinerators 1960s and 70s because of all the emissions, particularly dioxins. Dioxins were the most toxic ingredients in Agent Orange, which the United States used to destroy crops and jungle in the Vietnam War. These chemicals had horrible lasting effects on exposed members of the Vietnamese population, causing deformities, gene mutations and cancer. However, following the Clean Air Act of 1970, WtE plants must conform to much stricter emissions standards. According to Paul Gilman, Chief Sustainability Officer at Covanta, WtE is now cleaner than coal, releasing less greenhouse gases and dioxins. [15]

The EPA now classifies WtE as renewable energy, but prioritizes reduction, reuse, and recycling over incineration. According to Dave Ciplet, U.S. coordinator for the Global Alliance for Incinerator Alternatives, "by recycling materials, you conserve three to five times more energy than is generated by incinerating them." [16]

However, recycling is stagnating in the US; the recycling rate has barely increased in the last 10 years, hovering around 34%. [17] The economic feasibility of recycling is tied to how much money can be made back from the sale of recovered commodities like plastics, metals, and paper. These materials’ prices have been low in recent years, driving up the effective cost of recycling.

Florida[edit]

Because the state of Florida is densely populated, and there is not a lot of open land, they have taken heavily to incineration to produce energy from their MSW. Florida alone contains more than one fifth of the nation's WtE electricity generation, while only comprising about 6% of the nation's population.[18] An example is Lee County in Florida: they transform upwards of 10 million tons of trash into electricity, per month. This is enough to power 30,000 homes in the area; however, a lot of people do not recognize or appreciate the energy system they have in the county.[19] After Hurricane Irma, Florida was left with a lot of extra trash (upwards of a 20% increase for days). The WtE facilities were very useful in transforming that waste into usable electricity.

Edmonton, Canada[edit]

Edmonton has built an MSW to biofuels and chemicals facility, the only one of its kind in the world. They sort their waste manually and mechanically to pick out things that do not belong (such as electronics and tires), and send the organics to a composting facility. The remaining waste is shredded, heated, and converted to synthetic gases. This process keeps over 100,000 metric tons of waste out of landfills and provides 38 million liters of ethanol each year.[20] This facility has been in the making since 2008, and officially opened on June 4, 2014. Enerkem is also looking to open a facility in Mississippi because of its highly positive reactions by local community members.[21]

Conclusions[edit]

Waste-to-Energy can be an effective catch-all method for dealing with non-recyclable waste, generating a significant amount of energy in the process. However, the up-front cost of building WtE plants can be prohibitive, and the perception that incinerators are "dirty" or spew dangerous chemicals into the atmosphere can present an even bigger obstacle.

References[edit]

  1. https://www.eia.gov/energyexplained/?page=biomass_waste_to_energy
  2. U.S. Energy Information Administration
  3. http://www.nytimes.com/2008/07/04/business/worldbusiness/04iht-rbogwaste.html
  4. a b https://link.springer.com/article/10.1007/s10661-015-4401-1
  5. a b http://www.sciencedirect.com/science/article/pii/S0921344901001112
  6. a b https://circuit.bcit.ca/repository/islandora/object/repository%3A267/datastream/PDF/view
  7. https://blogs.scientificamerican.com/plugged-in/waste-to-energy-a-mountain-of-trash-or-a-pile-of-energy/
  8. https://www.nypirg.org/pubs/enviro/solidwaste/CommentstoDOEon1703LoanGuaranteeSolicitation5-27-14.pdf
  9. Seltenrich, Nate (2013, August 28). Incineration Versus Recycling: In Europe, A Debate Over Trash
  10. Tagliabue, John (2013, April 29). A City That Turns Garbage Into Energy Copes With a Shortage. The New York Times.
  11. Seltenrich, Nate (2013, August 28). Incineration Versus Recycling: In Europe, A Debate Over Trash
  12. Seltenrich, Nate (2013, August 28). Incineration Versus Recycling: In Europe, A Debate Over Trash
  13. Seltenrich, Nate (2013, August 28). Incineration Versus Recycling: In Europe, A Debate Over Trash
  14. Tagliabue, John (2013, April 29). A City That Turns Garbage Into Energy Copes With a Shortage. The New York Times.
  15. https://www.smithsonianmag.com/science-nature/burning-trash-solution-our-garbage-woes-or-are-advocates-just-blowing-smoke-180959924
  16. http://www.nytimes.com/2008/07/04/business/worldbusiness/04iht-rbogwaste.html
  17. https://www.nytimes.com/2015/01/11/us/garbage-incinerators-make-comeback-kindling-both-garbage-and-debate.html
  18. https://www.eia.gov/todayinenergy/detail.php?id=25732
  19. http://www.nbc-2.com/story/33071864/10-million-tons-of-trash-transformed-into-energy
  20. https://www.edmonton.ca/programs_services/garbage_waste/biofuels-facility.aspx
  21. http://www.chemicals-technology.com/projects/edmonton-facility/