To Incinerate your trash into something useful? Turning trash into energy is a smart solution that could help us divert landfills from growing, and even worsening, environmental issues. Unfortunately, landfills are still the preferred option for many cities in the world and around the globe.
The problem is that if you stick waste in an incinerator and burn it, the resulting fuels are harmful to the environment. Converting trash into energy is an invaluable step toward responsible waste management, diverting waste away from landfills, and decreasing environmental impact.
Waste-to-energy technologies also offer new sources of renewable energy. There are various waste-to-energy systems that incinerate with various eco footprints and efficiency levels; some have already proven commercial viability while others still need further work.
1. Hydrothermal Carbonization (HTC)
Thermochemical technologies transform organic waste into high-value-added products more economically than incineration can. By subjecting waste to high temperatures and killing viruses and bacteria at once, thermochemical technologies provide more environmentally friendly solutions than incineration with lower emissions production rates.
Hydrothermal carbonization (HTC) is one of the most promising waste-to-energy (WtE) technologies for biomass feedstocks, as it can transform wet waste streams like sewage sludges into solid fuel, hydrochar, and water-soluble by-products. HTC does not require pre-drying of its feedstock and can even produce ash that acts as a plant nutrient enhancer due to its high concentration of phosphorus; additionally, liquid byproducts produced during HTC can provide watering plants due to its potassium content.
HTC is a thermochemical technology that takes advantage of biomass's complexity, consisting of diverse chemical species with diverse properties. Therefore, modeling its reaction mechanisms and accurately predicting final product characteristics is difficult - particularly due to kinetic modeling taking place simultaneously across numerous reactions taking place at different temperatures and time intervals.
To meet the challenges associated with HTC prediction, many researchers have devised models that integrate different aspects into one comprehensive approach. These models employ a singular parameter that condenses all major influencers into an umbrella effect.
Reducing HTC prediction errors involves coupling it with other processes that enhance plant performance, such as anaerobic digestion (AD), which allows the valorization of wet substrates via the Rankine or Bryton cycle into biogas.
Predictive models for HTC are critical to expanding its use on a commercial scale. Such models could allow for the optimization of its process and ultimately decrease both costs and environmental impacts associated with the process.
2. Dendro Liquid Energy (DLE)
Waste-to-energy (WtE) industries around the world are flourishing, yet we remain far from reaching our ultimate goal of eliminating landfills altogether. Indeed, the US alone mismanages 80% of plastic waste and 90% of post-recycling material.
Therefore, the world is shifting toward WtE technologies with lower eco footprints and increased efficiency such as Hydrothermal Carbonization (HTC), Dry Anaerobic Digestion (AD), and Dendro Liquid Energy (DLE).
HTC transforms wet feedstock using heat to produce structured carbons similar to fossil fuels which take millions of years to form naturally. An acid catalyst at high pressure speeds up this process and encourages hydrochar production, an eco fuel suitable for heating and cooking applications.
AD is a process by which organic waste such as wastewater or animal manure is converted to biogas that can then be used as energy source, such as electricity generation or other forms. Although considered less polluting than incineration, dioxins and furans still produced by AD remain present. On the other hand, DLE produces nearly zero emissions while being four times more effective.
Plasma Arc Gasification is an innovative, cost-effective and eco-friendly waste-to-energy technology which converts non-recyclable plastics into syngas for use as electricity and heat generation, or used as an alternative source of natural gas or producing fertilizers.
Rising demand for sustainable development and energy independence from non-fossil fuel sources is driving growth in the waste-to-energy market, while government regulations promoting waste-to-energy are encouraging its proliferation. Government regulations like those promulgating waste-to-energy are further stimulating expansion in this sector; for example, European Investment Bank Group, one of the premier investors in sustainable development, recently unveiled the Climate Bank Roadmap which offers financial support for projects which align with EU Green Deal DNSH principles; however waste incineration projects do not qualify for these funds.
Beyond these trends, growth of this industry is driven by increased research and development spending by governments and private companies, with the purpose of improving existing waste-to-energy technologies or developing ones with reduced environmental impact. A recent study by Allied Market Research projected an annual compound annual compound growth rate of 7.9% between 2022-2032 for this market segment.
3. Anaerobic Digestion (AD)
Anaerobic Digestion (AD) is a natural biological process in which bacteria break down organic materials without the presence of oxygen, producing biogas which is then used as renewable energy source by being burned in CHP engines or cleanly introduced into the National Grid network.
AD has quickly gained in popularity as an environment-friendly waste treatment technology in the UK due to government incentives. Studies have also demonstrated it as being more eco-friendly and cost effective than traditional manure management methods; and its additional benefit of reducing greenhouse gases while simultaneously increasing soil nutrients is another plus point.
AD is a low-cost alternative to fossil fuels, particularly when compared with intermittent renewable resources like wind and solar.
An increasing amount of waste is being diverted away from landfill sites to AD plants, helping reduce pollution in local and regional communities. AD systems can accommodate different wet and dry waste materials including animal slurry and human solid and liquid wastes.
These systems combine CO2 capture with water treatment systems to offer a comprehensive WtE solution, making it convenient and sustainable for many communities.
Food waste recycling using AD technology can significantly lower emissions while simultaneously saving local communities money and improving environmental sustainability.
Biogas production provides many economic advantages to plant operators beyond simply avoiding landfill taxes, including significant economic gains for smaller dairy and livestock farms as it helps offset conventional fertilizer costs while producing digestate rich with nutrients that can be spread on fields as fertiliser, further mitigating emissions due to synthetic fertiliser use. It's especially advantageous in these cases where CAFOs or CAFO-like facilities could have higher operating costs from synthetic fertiliser use compared with farm communities that use biogas systems directly, like CAFOs for instance, where conventional fertiliser use could offset costs associated with conventional fertilizers while producing digestate rich digestate could then spread onto farms reducing emissions caused by synthetic fertiliser use compared with conventional options - something synthetic fertiliser use would do not do.
4. Incineration
Waste incineration (also referred to as "chemical recycling") is one of the best-known WtE techniques, consisting of burning organic components of waste streams to produce electricity and also used as an effective means for disposing medical, hazardous and municipal waste. Unfortunately, incineration usually is not net energy producing due to higher energy consumption than is produced; as such it has led many advocates and environmentalists to advocate and support alternative technologies instead.
Waste incineration is a form of thermal combustion that uses gasification and combustion to convert solid waste, such as MSW, commercial, industrial, and RDF, into electricity and heat. The gasification section converts waste to syngas which is burned in a conventional steam turbine generator to generate electricity - producing 20-25% efficiency when operated as combined heat and power (CHP) mode or 25-35% when producing electricity alone.
combustion process releases toxic pollutants into the environment, many of them short-lived; others, such as dioxins, remain airborne for prolonged periods and move with atmospheric currents worldwide; they then accumulate in people and animals leading to health concerns.
Combustion of toxic materials creates heavy metal oxides which pollute air and water sources, potentially releasing heavy metal oxides that can lead to serious illnesses or even death when inhaled or consumed by animals consuming these foods, especially as the chemicals spread along food chains from one animal to the next.
Recent advances in combustion technology and changes to waste management practices have significantly decreased emissions from waste incineration, such as prevention, reuse and recycling of waste streams that must be incinerated, leading to decreased energy and environmental costs associated with incineration processes. Pretreatment operations such as blending or filtering liquid waste streams before feeding it to an incinerator/industrial furnace for incineration purposes or screening/shredding solid waste streams have also helped significantly lower emissions generated during incineration processes.