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Garbage: Clean fuel with great electrical potential

There are around 2,100 thermovaluation plants around urban centers in the world and there are two essential reasons that governments have adopted this technology: (i) to change the landfill model, whose operation and results are highly aggressive both for the environment as for the neighbors of these landfills; and (ii) for substituting fossil fuels in thermal electric plants for less impact fuels, for which garbage is the ideal and stable generation fuel.
 

According to data of the Confederation of European Waste-to-Energy Plants (CEWEP) for 2016 in Europe obtained on average that 28% of the waste was sent to thermovaluation plants (TVP), 47% to recycling and composting and 24% to landfills, being Sweden the country with the greatest achievement with 50% of the waste in TVP’s, 49% in recycling and composting and just 1% in landfills (LF).
 

Meanwhile, Japan, a circular economy world leader, destines 70% to TVP’s and according to Geosyntec Consultants (as shown in Chart 1), there are 77 TVP’s in the US that process 90,000 tons of USW/day, i.e. 7%  of the waste of the country and with an electrical capability of 2,700 MW.

According to a study of the Solid Waste Association of North America (SWANA), and the Environmental Protection Agency (EPA), they compared the emissions of different technologies used in thermoelectric generation plants.
 

The main conclusions are:
 

  • Regarding carbon dioxide (CO2), emissions of a TVP are less offensive with the environment than those produced by thermal power plants (TPP) based on coal or fuel oil and natural gas. In other words, if coal power plants were substituted by TVP’s, for every MW-hr produced, CO2 emissions would be reduced by 63% –from 1,021 to 379kg–, a key indicator, now that Colombian has emission commitments with the Organization for Economic Cooperation and Development (OECD).
  • Regarding sulfur dioxide (SO₂), the reduction of emissions is considerable if compared to coal-based and fuel oil power generation production, from 5.9 kg/MW-hr for coal and 5.4 kg/MW-hr for fuel oil to just 0.36 kg/MW-hr for USW.
  • For nitric oxide (NO), its emissions are reduced by 10% approximately.


The technological development, regarding minimizing emissions in TVP’s from the beginning was shown in studies between 1990 and 2005 in the US as observed in Table 3.1.

From this we can conclude:
 

  • The reduction of emissions for dioxins/furans has been over 99%.
  • The reduction of emissions of mercury, cadmium, lead, and particle surpassed 95%.
  • The reduction of HCl and SO₂ elements reached values of 94 and 88% respectively.
  • The reduction of nitrogen oxides, NOx, reached 24%.
  • For 15 years, the average emissions from thermovaluation plants were below the limits established by EPA.


Lastly, governmental and non-governmental organizations, including the World Economic Forum (WEF), the European Union, the Center for American Progress, Columbia University scientists, CalRecycle, The Energy Recovery Council (ERC), among others have acknowledged that energy coming from USW significantly reduce greenhouse gases. As observed by Chart 2, we can conclude:
 

  • To produce one MWh of electric power with coal produces greenhouse gases (GHG) of approximately one ton of equivalent carbon dioxide (CO2-eq).
  • To produce a one MWh of electric power with gas produces more than 0.4 tons of CO2-eq
  • To produce a one MWh of electric power in a TVP produces -0.38 tCO2eq; i.e. including GHG by changing landfill waste and using it as fuel produces a negative emission of GHG. This is why it is referred to as clean fuel.

In 2017, close to 30.699 tons/day of waste were disposed of in Colombia in open-air landfills, contingency cells and processing plants and non-authorized places such as open-air landfills and temporary cells and bodies of water and other burned uncontrollably.
 

If we consider this waste as a clean fuel that could be used rationally and technically in TVP’s, then it could pass from being a polluting agent to be used for power generation as shown in table 4, with an installed capacity between 640 and 959 MW1

If we consider that the coal power plant capacity is approximately 1,700 MW and that the engineered capability of the Hidroituango power plant –which has not started operations– is 2,400 MW, with the non-recycled waste and that end up in several waste sites in Colombia, the installed capacity could between 37 and 56%, in comparison with coal-based thermal power plants or between 26 and 40%, in regards to Hidroituango.
 

The figures of energy potential for USW show a great opportunity to change waste disposal to a circular economy minimizing landfills for being obsolete and non-sustainable and also produce power from the waste of TVP’s or WtE, and for the electric industry to diversify its energy matrix to depend less on large water and thermal-based power plants, that besides the impact of the emissions consumes non-renewable resources and the effects of mining.

 


1 According to WtERT, every ton of waste has the potential to produce between 500 and 750 kWh of electrical power.

Consejo Editorial