Posting in Aerospace
Swapping out the expensive metals in car parts and lamp posts for a nearly-free coal burning by-product could save the environment and save money.
Swapping out the expensive metals in car parts and lamp posts for a nearly-free coal burning by-product could save the environment and save money, according to researchers from the Polytechnic Institute of New York University.
I spoke this week with Nikhil Gupta, associate professor of mechanical and aerospace engineering, about the unrealized benefits of fly ash. Here are excerpts of our discussion:
What is fly ash and where does it come from?
In power plants, when they burn coal in large quantities it generates ash. Some of the ash consists of hollow particles. These are the useful components. They're lightweight. They're a by-product of coal burning, so their price is very low. The only cost is in extracting the useful part and cleaning it.
How much fly ash is produced each year and what happens to it?
In the U.S., it's produced in about 70 million tons per year. Worldwide, the production is more than 300 million tons per year. In the U.S. about half of it is used in some applications. It's mixed with cement. But 35 million tons is still a lot of quantity. It is dumped in landfills. The big problem is that the particles, which are very low density, can fly with wind gusts. There are some toxins inside these particles, so it's not a good idea to just leave them in landfills. We need to find some applications for them where you can contain them in confined spaces.
You found that fly ash could be used to replace aluminum and magnesium in some products?
The main idea is to fill them into certain metals. Aluminum and magnesium are examples. We are also working with steel-based forms, where you'd put hollow fly ash inside steel. It can be beneficial in terms of reducing the weight of the total structure. Also, when you're replacing a metal, it's expensive. It's about $1 per pound. When you replace it with something that is almost free, the overall cost becomes lower.
What specific products could use fly ash?
Several of these components can be made in cars. We can start with some non-load bearing components like an engine cover. It doesn't take any load, so you don't have to worry about weakening the strength of the metal. With millions of cars sold every year, we can reduce some weight and we can reduce primary metal with these more environmentally unfriendly materials. This could be beneficial.
I also give the examples of lamp posts or park benches, where you put only a limited amount of load. Instead of making them solid with primary metals, we could make them with these other forms. They'll be lightweight and will use less aluminum or steel. Pollution associated with generating that much aluminum and steel is also saved.
What experiments did you do to determine that fly ash could be used in this way?
I worked with my collaborator at the University of Wisconsin - Milwaukee. His name is Pradeep Rohatgi. He runs a foundry and makes these materials in his lab. I have machines here that can test these materials in tension, compression and also on the conditions that are similar to high-speed car accidents. Once you put fly ash in aluminum or magnesium under compression, their energy absorption capabilities are very good. That means you don't compromise on the safety you get from primary metals, even by having this low cost environmentally unfriendly metal inside. That's an important part of the finding.
What are the downsides or challenges to using fly ash in this way?
These particles are hollow. Their walls are not perfectly made. We're trying to find only the component that's important for us. Having a process control is important. It's very important to understand the kind of product that will provide you the same level of strength. Without that it's difficult to understand how they would provide benefit.
What's the next step for this work?
We are working with some foundries in Wisconsin. We're trying to see if we can make some parts and put them into use with automakers so they feel more comfortable using them regularly. This would also help industry in the U.S. in becoming more competitive because the price can be pretty low. The whole cost of the part would be lower in this case.
Photo, top: Aluminum foundry
Photo, bottom: Nikhil Gupta
Mar 30, 2011
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Ok, here's my opinion whether or not you agree, that's completely up to you. This is a good idea finding more ways to utilize coal ash. Prevent it from going into a landfill!!! If it's recyclable then let's do it. Would you rather it stay in a landfill? Furthermore, I have done a bit a research on the net about the coal ash. What I have concluded is that there are TRACE amounts of heavy metals in the ash. There are also TRACE amount in many of the foods we eat daily ex: Fish, esp. shell fish, products sweetened with high-fructose corn syrup such as sodas, ketchup and even some breads. Legitimately the majority of us eat these things and it's no big deal. Why is recycling ash such a big deal when it can be used lower the costs of products and prevent it from going into a landfill? I fail to see why anyone would not want to recycle it. It is also used in bricks, concrete, cement, paint and etc... If more can be used for other products, I support it.
Coal ash is not "toxic." The careless repetition of this label is starting to destroy one of the most beneficial recycling efforts in America. Coal ash contains trace amounts of metals, just like most materials you encounter in everyday life. (For example: compact fluorescent light bulbs, dental fillings, daily multivitamin pills, etc.) The levels of metals in coal ash are similar to or lower than the metals present in the materials coal ash replaces when it is recycled. Those metals are only "toxic" if they have a way to get out of the ash and into you in sufficient quantities to cause harm. Citizens for Recycling First supports recycling coal ash as a safe, environmentally preferable alternative to disposal. Please help us protect practices that keep millions of tons of coal ash out of landfills, conserve natural resources, and reduce greenhouse gas emissions by millions of tons per year. Please help us by not falsely labeling all coal ash as "toxic."
The commenters here all make very good points about the hazardous nature of the fly ash, the difficulty in recycling used metal parts made with it, etc. Moreover, it sounds to me like using fly ash as "filler" for metal parts cheapens them, if only by an acceptable amount. Waste products cheapening metal parts and the Chinese have twice as much of the waste product??? It's just incredible that it's not already in our drywall, pet food and toothpaste!!! (or is it???)
1) Coal going away? What planet are you on? (Apparently not Smart Planet, yukyukyuk.) That's unfortunately a problem this idea won't have to deal with anytime soon. 2) The elements in fly ash mentioned as hazards (arsenic, lead, cadmium, and radioactive stuff) are there in TRACE amounts. The EPA is only worried because coal-fired power plants produce a LOT of fly ash, and the EPA doesn't want this bad stuff leaching out from a landfill into ground water. I wouldn't support making baby toys from fly ash, but lamp posts? Meh. No disclaimer needed. I'm not associated with this research at all.
China consumes three times more coal than the US, the second most user. It would follow that when the US develops the process, the PRC will exploit it.
Isn't it one of our goals to get rid of burning coal in the first place? After all there is no such thing as "clean coal" no matter how much spin the coal industry puts on it. Maybe we can use the available tonnage of fly ash available but what happens when we are weaned off coal?
Fly ash is being considered by epa as a toxic waste whY? Becasue it contains heavy metals such as arsenic, lead and cadlium It is not as easy or without repourcussions as you suggest Fly ashes vary widely in terms of how much carbon they have etc as they are made from various kinds of coal each of which have a unique chemical signature so it is difficult to design with one and expect to have the same results with another fly ash The take away? When you design with this waste product you have very problematic chemicals in it and it is very variable in its chemistry. There is no free lunch with fly ash DO we want this spread around the environment??
It does bring up some questions. How does his idea for cars impact the goal of producing cars, and many other products, to be easier to recycle at end of life? Does adding this material into the metal make recycling difficult? He mentions using it in light poles. Static light poles may be considered lightly loaded, but have they tested the altered metals for how they react under the varying directional wind forces encountered in bad weather? Will it hold up to a shifting 80 mph wind with a 100 lb street light mounted 40 feet up?