It is essential to increase the demand for energy supply produced with technologies for the conversion of abundant renewable materials and at the same time reduce CO2 emissions.
Therefore, in the context of a circular economy, residual materials from industrial production and organic waste, including biomass, instead of being disposed of in landfills, through the use of efficient technologies can be transformed to recover their energy. Among thermochemical treatments, thermal conversion and gasification are highly attractive solutions.
Emerging economies will double their waste generation in the next 25 years. Currently, 75% of this waste ends up in landfills and incinerators to generate electricity, and only 25% is recycled. Both gasification and thermal conversion provide options for producing clean renewable energy. These are not new technologies; however, they are quite new in the market. Energy recovery from waste is a relatively new industry.
Application and prospects for small-scale thermal conversion in the circular economy
Conversion technologies are thermal, chemical, mechanical, and/or biological processes capable of converting residual solid and liquid waste into useful, clean renewable energy; green chemical and fuel products.
During the last decades the growing consumption of energy, the demographic impulse, the expansion of industrialization and extensive use of fossil fuels that continues to dominate, have created environmental concerns with climate consequences. However, new energy generation alternatives such as wind, solar, geothermal, tidal, waste and biomass recovery are now more efficient and popular.
Combustion of mass, whatever it may be, still provides more easily extractable energy. Increasing demand for energy supply from renewable organic waste, which is abundant, is critical to producing affordable green fuels using conversion technologies, while reducing CO2 emissions.
The waste hierarchy and waste-to-energy processes
It is important to emphasize that the current waste hierarchy largely reflects the preferred environmental option from a climate perspective: disposal to landfill or incineration with little or no energy recovery, is often the least favorable option for reducing greenhouse gas emissions.
On the contrary, the prevention, reuse and recycling of waste have the greatest potential to reduce greenhouse (GHG) emissions. For waste streams that cannot not easily be sorted out, thermal conversion is the best option from an environmental and economic stand point.
In that context, it is clear that energy recovery by thermal conversion is preferable to recycling.
Are conversion technologies incineration?
Incineration is literally the burning (combustion) of organic substances contained in waste materials in an oxygen-rich environment where the material burns and produces heat and carbon dioxide, along with a variety of other pollutants including dioxins, furans, NOx and SOx. Unlike incinerators, conversion technologies, including gasification, thermal conversion, anaerobic digestion, and other processes, do not burn waste. They are thermal, mechanical and biological processes without combustion that convert organic materials into green fuels, clean renewable energy and other marketable products.
Thermal conversion vs. incineration
Thermal conversion has a number of important advantages over incineration.
- Thermal conversion for the treatment of MSW and other waste demonstrates excellent practical performance in controlling emissions of harmful substances such as dioxins, with levels dramatically lower than regulatory requirements.
- Depending on the incoming material, the plant is self-sustaining, it only requires fuel, such as natural gas, to start the operation.
- The thermal conversion plant does not produce wastewater effluents from the gas cleaning system. This obvious environmental advantage makes the system less expensive.
- Non-organic solid material can be separated from the carbon black and sent to a landfill for disposal.
- Carbon black has a multitude of industrial and commercial uses.
- Reclaimed metals (like in old tires) don’t rust and can be used again.
- Thermal conversion can treat low and high calorific value waste.
Contrary to incineration PuraEnviro® thermal conversion technology turns various raw materials, including organic waste, into syngas and green fuels. Thermochemical conversion of biomass is becoming a tool in developing energy away from fossil fuels.
Thermal conversion and gasification can process large amounts of bio industrial waste to create local renewable energy resources in a circular economy.
In the near future, recovery of waste biomass will have a positive effect on a sustained economy and the well-being of the population. For example, as an alternative to capital intensive electrical grid development, one of the problems of power supply in sparsely populated areas can be solved by boosting thermal conversion in combination with microgrid development, and in industrial applications, in complement with power supply from electric utilities.
This technology not only does not compete with recycling, but serves to improve recycling programs. In a circular economy, pre-processing and processing must increase the volume of recyclable materials. In addition, very large volume of end-of-life plastics, wood and paper waste that otherwise cannot be sorted or recycled, are good high-energy raw materials for gasification and renewable fuels.