A Solution to Our Plastic Problem

Did you know we can turn our used plastics into diesel fuel? A cleaner version of diesel at that!

Both plastics and diesel fuel are made from crude oil so it would make sense that we could turn plastics back into an oily form and thus into diesel fuel. This process is known as pyrolysis, which simply means decomposing a substance at high temperatures with the absence of air. When we do this to plastics, it breaks down the hydrocarbon bonds and reverts them back to an oily state. Then, all that is needed to turn this oil into ultra-low sulfur diesel (ULSD) fuel is a bit of purifying. This process does take a fair amount of electrical energy to run the converter, but it is significantly better for the environment than making ULSD fuel out of newly harvested crude oil. A study done by Argonne National Laboratory (a science and engineering lab run by the University of Chicago for the U.S. Department of Energy) in 2017 found that ULSD fuel created from non-recycled plastic creates 9% fewer greenhouse gasses, uses 58% less water, and uses 93% less energy than creating ULSD fuel from crude oil.

The 9% reduction of greenhouse gasses is due to the fact that to get the feedstock (the building blocks for the fuel) in the plastic-to-fuel process emits hardly any greenhouse gasses. The only significant source of greenhouse gas emissions created in this process is from the electrical power needed to sort the plastic from other waste products. On the other hand, to get the feedstock for ULSD fuel from crude oil takes distilling the oil and emitting unwanted gasses.

Fig. 3. Breakdown of life-cycle GHG emissions of base case (gCO2e/MJ diesel) from “life-cycle analysis of fuels from post-use non-recycled plastics” (2017)

The 58% reduction in water usage in the plastic-to-fuel process is because the only water used in the conversion is by the electrical power plant to create the power needed to run the reactors. Contrarily, the water used to cool the plant during the feedstock stage and refining of crude oil into ULSD fuel is the main driver of water usage with traditional production. This water reduction is becoming more and more important as our freshwater resources begin to get scarce and water shortages become more common.

Fig. 6. Comparison of life-cycle water consumption of NRP-derived vs. petroleum ULSD fuel. From “life-cycle analysis of fuels from post-use non-recycled plastics” (2017)

The 93% reduction in energy consumption in the plastic-to-fuel process is because the only fossil fuel energy consumed by this process is the sorting of plastics and running the reactors, whereas the conversion of crude oil into ULSD fuel is an energy-intensive process all the way around. Most of the consumption coming from the vehicles and machinery needed to extract and transport the new crude oil from the ground to the refineries.

Fig. 5. Breakdown of base case life-cycle fossil energy consumption. From “life-cycle analysis of fuels from post-use non-recycled plastics” (2017)

A study was done by Themelis and Mussche (two researchers at the University of Columbia Earth Engineering Center) in 2014 that found that in 2011 alone, 31 million metric tons of plastic ended up in U.S. landfills. A National Geographic writer, Laura Parker, states that of the 8.3 billion metric tons of plastic that have been created, 6.3 billion tons of it has become waste either in landfills or scattered throughout the natural environment. Themelis and Mussche (2014) found that we can turn those 31 million tons of plastic into 144 million barrels of ULSD fuel. That means that if we somehow collected all 6.3 billion tons of waste plastic that are floating (some of it literally) around the natural environment, we could create 29.7 billion barrels of ULSD fuel. The U.S. alone refines 1 billion barrels of ULSD fuel a year, but if we were able to collect all the waste plastic the U.S. would not have to refine crude oil into ULSD fuel for 29 years. That is definitely enough time to find a solution to fossil fuels and then some.

Turning crude oil into ULSD fuel is an intensive process and not that efficient. When the typical U.S. refinery turns one barrel of oil into ULSD fuel we only get 12 gallons out of the 42-gallon barrel. That is a return rate of only 25%. When we turn non-recycled plastic into diesel fuel we get return rate between 60% to 80%. This return rate, and the fact that creating ULSD fuel is way better for the environment seems like this process should be more widely practiced. So why haven’t many of us heard of this process?

Well, many grassroots campaigns have shut down the implementation of these reactors because they believe that the noise and air pollution is not what they want in their backyards. This argument is flawed, in my eyes, because the pollution created by these reactors is minimal and is far less damaging than getting new crude oil out of the ground, shipping it from the Middle East to the U.S., and refining it. Plus, this technology has the potential to take millions, if not billions, of tons of waste plastic out of landfills. I believe that these benefits greatly outway the costs.

The other argument against these reactors is that we are trying to move away from fossil fuels and plastics and this is adding another way to use them and hang onto them. I can see some validity in this argument because it will make another market focused on fossil fuels and plastics, but in a statement made to the Guardian Foy Group’s (an industrial electrical contracting company) managing director, Stuart Clark said that “Waste plastics are worthless at the moment, so by giving them a value, it makes people and businesses less inclined to simply throw that plastic away.” I think that Stuart is on the right track here, I do not think this new market will encourage more production and more waste of plastics. I think it will encourage the exact opposite reaction because if they have value companies and people will want to capitalize on that value themselves and not just throw it away like they have been doing. In addition to that, it is hard to see the world going from fossil fuels one day to completely renewable the next. I think we need a couple of stepping stone technologies and this could be one of them.

One promising organization tackling this situation here in the U.S. is Ecofuel Technologies. Ecofuel Technologies is the brainchild of polymer scientist Dr. Swaminathan Ramesh. Ramesh created a small-to-medium scale reactor that is capable of operating out of the back of a truck or on a boat and can be taken to where it is needed most. This reactor is special because it can convert plastics directly to ULSD fuel with no additional refining. His reactor is capable of processing 100 to 10,000 pounds of plastic a day which results in 10 to 1,000 gallons of ULSD fuel respectively. The reason I find this reactor so special and more interesting than the large-scale industrial reactors is because this reactor can go to the problem. We can put these on the back of boats and take them to the islands that need it the most, cleaning up the heavily polluted beaches and waterways. This is not just great for the environment; it will also help the smaller developing island nations because they not only have a chance to reduce the number of plastics in their landfills and on their beaches but also increase their economy at the same time. The ULSD fuel that they create can either be sold to other nations for a profit or stay on the island to reduce the amount of ULSD fuel they need to import. Whichever way you slice it, the nation and the oceans win.

The oil refinery business in the U.S. is a huge market making 1 billion barrels of ULSD fuel per year, and we cannot completely run the nation’s diesel cars off this emerging technology. However, we are going to turn a product that was previously seen as trash into something profitable and helpful to the environment and that is a major step forward in my opinion.

 

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