I hope everybody agrees upon one thing. We are complex species. Our world is multi- layered. Our building methods are tedious. Our food, complex and processed. Our clothing is factory made and our transportation methods- highly advanced. Our every single act of "living" needs energy and our every single life cycle process generates tremendous waste.
If we look around us, every species have its own uniqueness. Some species have unique migratory patterns, some have peculiar eating habits, some have unique vibrant colors, while some have unique eating patterns. I wonder if consuming energy and creating waste is our uniqueness.
More than 250 million tons of solid waste is produced each year in the United States. Out of which, more than half is discarded in the landfills. Our life cycle processes create so much waste that it has to be either tucked away in landfills or burned in incinerators. Most of the other countries in the world do not have this kind of " luxury". Many developing countries face a gigantic issue of waste management and waste is seen floating in piles through roads, slums, water bodies, open space, etc. Waste is far less important to be discarded properly. It affects our environment, contaminates our natural habitat and disturbs our ecological balance.
Can we somehow bridge this gap between the energy we consume and the waste we produce?
-Enter Denmark.
For many small and dense countries around the world, [especially Europe] like Denmark, creating landfills is not an option. There is no physical space where the waste material can stay for hundreds of years to come. "Abandoned and forgotten" waste material is creating a new movement throughout the country. Which has helped Denmark cut energy costs and reduce dependence on oil and gas. They now use their solid waste as an effective source to generate electricity and heat for most of the neighborhoods in the towns such as Horsholm and Copenhagen. District heating, steam for industrial purposes, district cooling is managed at such "waste-to-energy" creating facility along with creating electricity. Any type of waste that is non-decomposing, can not be recycled or upcycled through economically and environmentally safe processes is used as a source of energy.
There are two primary methods through which energy is produced-
1. In the landfills, through landfill gases- Inside the landfill, as the waste keeps decomposing, it collects landfill gases. the gases are collected in the underground wells and are used to generate electricity. One ton of waste can generate 65kWh of electricity.
2. Burning of waste material to create energy- Waste is combusted on a moving grate while air is added to the process. Little or no pre-treatment of waste is needed. Waste is burned to heat a boiler that generates steam for moves a turbine and generates electricity. One ton of waste can generate 590kWh of electricity.
In the landfill gas collecting process methane gas is generated from garbage, while in the incinerator process, carbon dioxide is produced. Methane being recognized as highly potent for global warming, Denmark has invested considerable research and finances to design type 2 incinerators. They use the cutting edge technology in filtering and prevent hazardous substance such as Hydrochloric Acid, Sulfur Dioxide, Nitrogen Dioxide,other heavy metals, etc. from escaping back in the atmosphere. Every waste incinerating plant has emission levels upto twenty percent less than that are allowed by law. It is their claim that a waste incinerating plant burns more cleanly than that of wood burning fire places and backyard barbeques in the neighborhood homes. Denmark now regards garbage as "clean-er" energy source, and has about thirty operational plants.
Integration of the "waste-to-energy" plants in the neighborhood.
One of the commendable parts, according to me, about the waste to energy program is the integration of this concept on the grass-root level in the community planning. Waste-to -energy plants are integrated in the community development at the design stage. They are not an after thought. They are stretigically placed in the master plan so that electricity and heat both can be pumped in the communities at the optimum economic value. Yet they are away from the main neighborhood activity areas. They appeal to the aesthetic sence of the community because they are designed as sculptures, confirming to the vernacular architecture. They are served by dedicated garbage carrying routes. As a result, heating and electicity costs in such communities are considerably lower. Neighborhoods are quite self sufficient in managing the waste it creates in this manner.
There are pros and cons to each technology we use.
Incinerating waste has its own by-products or more waste. Besides electicity and heat, there are other by products such as flue gas, waste water, bottom ash, fly ash and residues from flue gas treatment. The glue gas and waste water have to be cleaned according to the strict environmental standards prior to their emission, while bottom ash and fly ash and the other residues need specialized treatment facilities.Secondly, We need to sacrifice "not in my backyard" attitude, since such plants can only be effective if they are located close to the community.
But most importantly we need to take responsibility for the waste we create. No energy source [except for natural] can be entirely clean. The fact that many countries are looking at garbage waste as a clean-er source of energy is worth taking note about and researching further. Can waste be looked at as a sustainable, indegenious raw material that is forever available? More energy generation for our consumption needs can never be sustainable. Energy recovery systems such as waste-to-energy concepts have potential to create energy independence for small communities if not for the entire countries. And that self sustainance according to me is a key to survive in the post hydrocarbon world.
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