First Published in the UCD College Tribune
Humans have an incredibly extensive waste problem. Right now, most of that waste is sent to landfills where it takes up space for thousands of years, leaching harmful chemicals and gases into the soil and atmosphere. Alternatively, we send our waste to incinerators which burn it for energy, but which release harmful greenhouse gases (GHGs) and toxic by-products in the process. A large proportion of our plastic waste ends up in the ocean, where it strangles and poisons fish, seabirds and marine mammals. What if I told you that there was a way to get rid of almost any type of waste in one machine, that the machine would release no harmful chemicals or GHGs, and that the process would produce useful by-products and excess energy that could be sold back to the grid? Such a machine exists right now; the plasma waste converter (PWC).
While incinerators are able to extract about 15% of the potential energy from rubbish, PWCs can extract an incredible 80% through a process called ‘gasification’. Plasma is ionised gas, meaning that it contains roughly equal numbers of positively charged ions and negatively charged electrons. It is often called the fourth state of matter since its characteristics are so different to those of liquids, solids and gases.
One way you can make plasma is by creating an arc of electricity between two rods, then passing a gas like argon through it. This set-up is known as a plasma torch and can heat gases to a higher temperature than the surface of the sun. Plasma torches were invented by NASA in the 60s to test how much heat the hulls of their spaceships could withstand. The crucial difference between using a plasma torch and using an incinerator is that in PWCs, combustion doesn’t take place. That means no smoke, no GHGs and no ash. The plasma breaks down the bonds between atoms, separating them into very simple forms. Despite the extremely high temperatures, it would be wrong to say that the waste is being ‘burned’; rather it is being decomposed at an accelerated rate.
One of the products of gasification is, you guessed it, gas. This energy-rich gas, known as syngas, is largely made up of hydrogen and carbon monoxide. Syngas mainly comes from the gasification of organic matter. As the gas expands, it spins a turbine, generating electricity. The high temperature of the gas can also be used to evaporate water, generating steam to turn another turbine. The syngas itself can then be burned for fuel or scrubbed with water and released safely. Remember, all of this energy production and revenue is coming from rubbish. We are talking about the plastics that are decimating marine life. Metals, fabrics, wood, even toxic or hazardous waste from industrial run-off or medical facilities. This is stuff that we desperately need to get rid of and by getting rid of it like this, we can also take some of the stress off an already strained energy production sector.
The solid by-product of gasification is called ‘slag’. Slag is produced mainly from inorganic materials like metals. It can be used in construction to bulk up concrete and tarmac, making it a very useful commodity. The molten slag also pools at the bottom of the chamber and helps to maintain the temperature, reducing the energy consumption of the PWC. The real magic happens when you pass compressed air through molten slag to create a material known as ‘rock wool’. Rock wool is currently made by drilling into rock, melting it down and spinning it in a centrifuge. Made in this way, rock wool is sold at one US dollar per pound. When it’s made of rubbish instead, it can be sold at just ten cent per pound.
Rock wool can be used in a number of ways. As an insulation material, it is twice as efficient as fibreglass and could significantly decrease heating and air conditioning bills, further reducing the carbon footprint of gasification. Surprisingly, you can also hydroponically grow plants from seed in rock wool. Perhaps its most amazing use is that it can clean up oil spills. Rock wool is lighter than water and extremely absorbent. This means that if you spread it out over the surface of an oil spill, it will float and absorb all the oil. The rock wool can then be collected with relative ease. Slag and rock wool are two more saleable products that can increase the economic viability of plasma waste conversion.
PWCs are currently being built all around the world. Some plants are already so efficient that they need to take rubbish out of landfills to use as feedstock. There is even a mobile plasma torch on the back of a truck in the US which can be jammed straight into landfills, which act as makeshift gasification chambers. The need to reduce GHG emissions and simultaneously fix our massive waste problem has generated huge interest in PWCs in recent years. Landfills have only one way to make money; they charge you a ‘tipping fee’ for getting rid of your waste. Since PWCs can generate revenue from both energy production and by-products, they can make their tipping fees much more competitive.
So why haven’t these things solved the problems of pollution and climate change already? The answer is largely that PWCs are still a relatively new technology. The cost of building and operating one is still much higher than that of some of its competitors including landfills and incinerators. There has not yet been standardisation of the design and thus the huge and complex machinery must be custom-built every time. The energy needed to power PWCs is also very high, especially compared to incineration, which requires only a match. It must be said, however, that although it takes a lot of energy to run a PWC, you will very quickly make all that energy back and more. PWCs are extremely efficient long-term; unfortunately, short-term profits dictate much of what happens in society.
One worry is that by making waste a profitable commodity, we encourage people and companies to keep polluting with impunity. The best way to solve pollution is not to pollute more and then clean it up better. It is to reduce the amount of pollution we are producing, whether that is by reducing our individual consumption, or by researching innovative ways to package our goods without making a mess. There is, on the other hand, already a lot of waste out there, languishing in landfills and contributing to the decimation of marine ecosystems. The best thing to do with all that waste is to get rid of it with the fewest possible emissions and the most possible benefits. PWCs may be just the technology for the job.
The price of fossil fuels is slowly being raised by various economic policies to reflect the cost to life on earth and we need to find as many alternative sources of energy as we can. With countless landfills already full and the world still producing around 2 billion tonnes of waste per year, rubbish will not be scarce for a very long time. This really is a win win win win win. One machine can get rid of harmful waste, cut GHG emissions, produce fuel, energy and construction materials and clean up oil spills all while making a profit. An investment in plasma waste converters is not only economically sound, it is also an investment in the future of our planet.
10 thoughts on “Win Win Win Win: The Magic Science of Plasma Waste Converters”
That’s really cool! If is really so clean as your article claims, then I do hope the technology is put to good use.
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Thanks Jessica! From what I can tell it is a whole lot cleaner than any other waste management system we’ve thought of so far. I hope they catch on soon. We need it!
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That we do. I just had a baby a week ago, and although we are cloth diapering, the first few days we used disposable diapers from an eco friendly brand. When I was taking out the used diapers, my boyfriend and I both noticed just how much waste was created in just under a week, and when you think about how much that adds up over the course of up to 2 years, it’s really horrible! Seeing that makes me all the more resolute in cloth diapering. There are so many ways that we as individuals can minimise our footprint, if we’d all just readjust our thinking a little. And anything that can be done to more efficiently reduce the amount of trash that is being produced should be done.
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Congratulations on the new baby! I couldn’t agree more that small changes are vital to the fights against climate change and waste pollution but it must be said that huge corporations are responsible for the majority of both. As well as cutting down our own waste and emissions we must also protest as visibly as we can so that governments know that we will not let companies like Shell and Starbucks decimate the biodiversity of the planet as they currently are. That is not to downplay the importance of the readjustments you talk about like using cloth diapers.
Each time we reduce the overall amount of damaging waste being dumped on this planet, we improve the lives and futures of every animal that lives here. It is important to remember, however, that you are not the one who produces the waste and when there is little alternative available, the full blame cannot be put on the consumer. If one person starts using cloth diapers, that is a step forward. If massive companies switch to exclusively producing cloth diapers, then that is one huge leap.
Thanks again for the comment. I hope the baby isn’t keeping you up too late 😁
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Potentially the answer to the World’s waste problem…A great article I do remember when my son was in the waste business him talking about how waste can be used to generate electricity I will be revising that conversation which I do on occasions as the waste problem is huge in Asia where I live and a topic often discussed between us. Yes, as individuals we can make small changes which help the problem but if collectively we consumers banded together we could really make a difference but the source needs to be addressed by governments and the like with the manufacturers and companies like Shell and Starbucks as you have mentioned…I hope that foresight can be used very soon to address this problem and that companies who produce waste contribute to the costs of the solution…I can but dream 🙂 A great post and I will link back to this in my Monday’s post on Plastic waste…Thank you for sharing 🙂
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Thanks so much for the comment Carol! I agree with everything you say. Asia is absolutely leading the way in this technology so you’re in the right place for it. I look forward to reading your article on plastic waste. It is such a huge problem and PWCs may help to solve it. I wrote an article recently on plastic waste in the ocean if you’re looking for more research sources. Thanks again for the comment! 😁
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Great article, we need to pay more attention to finding solutions for our problems, it is so sad that the manufacturers don’t care , they only think about profits and more should be said about the landfills and what needs to be done to reduce the pile of waste in them
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Thanks so much! I couldn’t agree more. The time has come to start throwing everything we can at these problems. In fact we should have been doing so a long time ago. Profits dictate far too much of what happens to this planet. There are so many problems with landfills, not least of which being that half of the gases produced are carbon dioxide, while the other half are methane, a greenhouse gas roughly 30 times as potent as CO2. Getting PWCs up and running around the globe is an urgent and necessary expense
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