Waste to Electricity! Route to Zero Waste Society
By: Muhammad Noman
Tags: Waste Management, Power, Energy, Gasification, Incinerator

Following is the link:

https://www.youtube.com/watch?v=bkhQYycpdOg

TED Talk by Mike Hart

Summary: In 2004, he formed Sierra Energy and partnered with the University of California at Davis to develop a groundbreaking technology that takes almost any form of waste and turns it into clean energy and fuels for his locomotive fleet. This solution not only provides a new form of clean energy but mitigates another highly problematic pollutant: trash. Humans will make more than 2.2 billion tons of garbage every year by 2025. In turn, each ton of garbage emits the equivalent of 6.2 tons of CO2 into the atmosphere. This means that over 13 billion tons of greenhouse gasses can be eliminated with this process- enough to achieve the entire Paris target for GHG!

Sierra Energy has taken one of the oldest technologies in the world — the blast furnace — and modified it into something they’ve called a FastOx® Gasifier. This new machine breaks down waste at about 4,000 degrees Fahrenheit (or 2,200 degrees Celsius) and converts it into carbon monoxide and hydrogen, which can then be turned into renewable fuel, electricity, and more.

“It is not burning; it’s breaking down the waste molecularly. Doesn’t matter what you put in, it comes out as gas, liquid metal, and liquid stone- all products which can be reused. Additionally, because of the high temperatures, the gasifier is able to handle a complete gamut of waste materials — from garbage to hazardous waste.”

Mike Hart

BLOG:

Pakistan generates about 48.5 million tons of solid waste a year, which has been increasing more than 2 percent annually. Like other developing countries, Pakistan lacks waste management infrastructure, creating serious environmental problems. Most municipal waste is either burned, dumped or buried on vacant lots, threatening the health and welfare of the general population. The Government of Pakistan (GOP) estimates that 87,000 tons of solid waste is generated per day, mostly from major metropolitan areas. Karachi, Pakistan’s largest city, generates more than 13,500 tons of municipal waste daily. All major cities face enormous challenges on how to manage urban waste.

Win Win Deal — Waste to Energy

A waste to energy electricity plant converts Waste/rubbish into electricity some plants supply heat to district heating Systems, how does it work from the most widely used technology takes waste and burns, it the heat created is used to make a steam which in turn drives a turbine that generates electricity the technique we’re going to look at is widely used around the world you’ll notice that all the power plants are very big this is a process that works best on a large scale. Incinerating waste creates emissions and residues and part of the process is focused on dealing with these achieving a high rate of efficiency with a low volume of by products is the aim there are many systems of varying complexity but they all work on the same principles to set up this kind of waste-to-energy system. We need a stockpile of waste a furnace a boiler with heat exchangers a water supply system a turbine and a generator the waste is collected and delivered to the plant where it is stored in large bunkers. it’s transferred from the bunkers to a chute leading to a moving grate in the furnace below the plants boiler the temperature and the furnace is very high the gases in it are heated to over 850 degrees for at least 2 seconds to make sure all the waste gets burned completely, to form stable end products the residue left behind is called bottom ash. It is non hazardous it’s may sent for recycling and is often used by the construction industry around 20% by weight of the waste ends up as bottom ash the intense heat from the furnace rises into a series of chambers in the boiler. The idea is to capture the thermal energy as efficiently as possible in the boiler, heat exchangers a series of pipes filled with water a bit like a household radiator the heat vaporizes the water to form superheated high-pressure steam this is sent to the turbine where it encounters a series of turbine blades the high pressure steam forces the blades to rotate at high speed driving the generator in order to make electricity. The electricity is fed to the power grid for use by industry and the local community water travels through the system in a loosed-loop cycle after passing through the turbines of steam it is allowed to condense and is then returned to the heat exchangers to be heated again some waste-to-energy plants incorporate a district heating system into the cycle the low-pressure steam from the turbine heats a second closed water loop leading out into the community where in turn heats individual systems gas emissions from the boiler are known as flue gas.

Power Plant Cycle

Flue gas must be treated before being released from the plants chimney stack it’s processed sing a series of absorption scrubbing and filtering systems. There are two other types of waste product the first is the waste water that wet flue gas treatment plants produce this is treated than released the second is fly ash which contains toxic chemicals and consists of solid particles in the flue gas fly ash is sometimes treated sometimes not but either way it must be disposed of as hazardous waste fly ash represents less than five percent of the waste input of a waste to energy plant waste to energy or energy from waste technology is continually under development today the most advanced plants using this technology have described are up to 98% efficient in capturing the energy they generate however there is debate about the effects on health of incineration and its byproducts and about the co2 produced must have stringent controls on emissions and all emissions and residues must monitored by Environment Agency, there are various other forms of waste to energy processes some examples are gasification which produces combustible gases anaerobic digestion which produces methane rich biogas and pyrolysis which produces bio oil investment in waste-to-energy plants does depend on our continuing to produce burnable waste which some might see as an incentive to create it there is also debate about the indirect environmental impacts of making biofuels whatever the process used the objective is to reduce volumes of waste in particular to send as little as possible to landfill, if the PAKISTAN government wants that waste-to-energy processes will account for 25 percent of municipal waste treatment waste to energy technologies recover value from our waste and are therefore a source of renewable energy.