Project turns plastic waste in the sea into vehicle fuels
WE have all seen the terrible images of beaches and harbours covered in plastic waste, or of huge islands of bottles and bags floating on the surface of the ocean.
In a 2016 report (bit.ly/1Ou5wDU), the World Economic Forum and the Ellen MacArthur Foundation predicted that if we continue to produce plastics at current rates, and continue to fail to dispose of them properly, by 2050, there will be more plastic in the ocean than fish. In the past 50 years, plastic production has increased 20-fold, and is expected to double again in the next 20 years. More than 300m t/y of plastic is produced worldwide, and 50% of that is used only once before being thrown away. Just 14% is recycled, some is landfilled, but around 8m t/y of plastic ends up in the ocean. Given that plastics can take hundreds of years to degrade, this is a huge problem. But what can we do?
It seems likely that more than one solution is going to be necessary to solve such a colossal waste management problem, but there are people working on it. Jim Holm – known to his friends as “Captain Homer” – a sailing boat captain from Santa Cruz, California, and his friend and colleague Swaminathan Ramesh, a retired organic chemist, say that their system could help solve the problem.
Ramesh has developed a small, mobile reactor which can take waste plastic and convert it directly into diesel. The reactor could be driven around on a truck to where it is needed, for example a beach with an acute waste problem, or even carried on the back of a boat, to provide fuel for its engines.
“We’re not telling anybody that we have the one single solution, but we pretty firmly believe that plastic-to-fuel conversion can be a very valuable part of an overall response."
There has been some initial criticism of the idea, but Holm says it is the only technology he is aware of that gives an end-of-life use to plastic which can no longer be recycled and would otherwise go to landfill.
“People say we’re still creating a fossil fuel and still contributing to climate change and they’re correct, but to produce fuel through this method is a lot less carbon-intensive than it is to go out in the middle of the ocean or some desert and dig a hole to suck out the oil and ship it here and there and refine it a few times. Every little step we take towards reducing carbon is a smart move,” he says.
Diesel is a valuable commodity. Turn freely available, non- recyclable waste into something you can sell and make money from, and suddenly, you have a viable business proposition.
“We’re just trying to reach people where they’re human,” says Holm. “Most of us want to make a profit. People in our industry don’t offer solutions, especially practical solutions. They just say we should outlaw plastics products. In some cases I think that’s good but it’s not going to solve the issue. It’s going to take all of these things, legislation, and change in our personal habits, but it’s also going to take some kind of motivation to want to change. That’s where plastic-to-fuel comes in, because there’s financial motivation.”
With the reliance on single-use plastic packaging and fossil fuels for transport unlikely to diminish any time soon, Ramesh and Holm’s system could, as it were, kill two birds with one stone.
Holm has been captaining sailing vessels since the late 1970s. He has always been passionate about protecting the ocean environment and since the mid-1990s has been running educational awareness programmes and sailing trips for schoolchildren and locals in California. His varied trips have included taking highschool students and their teachers across the Atlantic, college students to Hawaii, Cuba and Brazil, and slightly closer to home, grade 5 and 6 students, aged 10–12, around Monterey Bay.
“During 40 years of floating around out there I’ve seen that the oceans have been having more and more difficulties, and one of those is plastics,” he says.
The seminal moment came during a trip down the Panama Canal a few years ago.
“While we were waiting for some nasty weather to decide whether it was going to hit Florida or not, we were amongst the islands of the canal. There was one particular tiny island all covered with plastic, and I thought, maybe there’s something I can do,” says Holm. “When I got back from that trip, I started looking at doing more educational things, I connected with a group of people and ended up forming what was then called the Clean Oceans Project.”
As well as educational projects, the group worked on various ideas to clean up the sea, and one of them was taking the plastic out of the ocean, and making it into fuel with a system small enough to be mounted on a boat. Negotiations with Japanese researchers attempting to do just that fell through, funding was hard to come by and the Clean Oceans Project looked like it was going to sink. Then, a little over two years ago, Holm met Ramesh.
Ramesh had been an organic research chemist at BASF, but following early retirement in 2005, had been working on his own project to turn plastics into fuel, inspired by an article he read on the energy content of polyethylenes and polypropylenes, which is almost identical to that of vehicle fuels. The polymers are made from crude oil, and Ramesh realised that if he could reverse the polymerisation reactions, he would have a liquid hydrocarbon again.
“Originally I had been looking at it as an energy problem. Around 60bn lbs of polyethylene and polypropylene waste every year goes to landfill in the US, and I thought that was a lot of plastic to waste,” says Ramesh.
Back in the 1970s, Ramesh’s former employer, BASF, had built a plant in Ludwigshafen to convert plastic waste back to oil for refining, but the venture failed. This was partly because of the cost of trucking in vast quantities of low-density plastic waste, and partly because the price of the oil produced was dictated by the cost of the crude oil it was competing with, then just US$20/bbl. Ramesh decided that it would make more economic sense to create a small unit that could be taken to where the waste was, and to develop a process to convert the waste directly into fuel, which is worth up to 300% more than crude.
He set up a company, EcoFuel Technologies, in an effort to commercialise the technology. Finding financial backing was difficult but a friend suggested he try San Francisco to look for investors. A contact he met there suggested he speak to Holm and his organisation, by then called Clean Oceans International after a reorganisation, and it was simply a case of perfect timing.
“I said, I have a solution looking for a problem, and I think we should work together,” says Ramesh.
Holm went to look at Ramesh’s reactor and realised it could be exactly what Clean Oceans International was looking for.
“We commissioned the first of his machines to be built for our purposes and a very small research-style machine. We had that built and brought here to the West Coast. Right now he has one in his shop in Michigan and we have one in our little laboratory here in California, and the object of the game is to see if we can make this technology small enough and cheap enough to make it available all over the world, so that people then have an option for recycling plastic that at this point doesn’t really exist.”
The reactor is contained within a unit measuring around 1.8 m by 1.2 m, and uses a catalysed pyrolysis process. Ramesh uses a metallocene catalyst, similar to those used to produce polyethylenes and polypropylenes in the first place. The catalyst is dispersed on a nano-porous support. Pyrolysis would usually require temperatures of 450-700˚C, but by using the catalyst, the temperature drops to 350-400˚C.
The unit can process around 200 lb/d (90 kg/d) of plastic to make around 20 gallons (75 l) of fuel, with a 90-95% conversion efficiency. 95% of the output is diesel, with around 5% petrol. The unit includes a mini fractionator to separate out the two different types of fuel.
“We do a lot of kinetic studies and simulations so we know the optimum amount of catalyst to use. Depending on the porous support, you can get different proportions of diesel or gasoline. You can use different-sized pores or you can change the amount of catalyst on them,” says Ramesh.
One of the major advantages of the catalyst system is its robustness. The plastic does not have to be cleaned and washed, it can just be fed straight in. The best yields of fuel come from polyethylene and polypropylene, although Ramesh says up to 20% polystyrene also gives good yields.
“Other types of plastics you can use, so long as you have the right engineering controls for the emissions, but not all plastics will give you high yields of fuel. PET, used in water bottles, is one of the worst plastics. It will give carbon dioxide and benzene, so you will get much lower yields, which is not good business sense anyway. If you are using PVC as your source, you’re going to get hydrogen chloride byproduct,” he says.
Ramesh has tested the diesel in standard generators and tried the petrol in his lawnmower with great success. You don’t need to take his word for it though. The researchers have also sent off multiple samples of the fuels for testing at an independent laboratory. Ramesh says that the samples met all of the criteria set out by ASTM International, an international standards organisation, including for flash point, freezing point and viscosity. The diesel’s cetane value (a measure of its combustibility, much like the octane value of petrol), was higher than that of standard diesel. But that’s not all.
“Depending on the source, the diesel is zero sulphur. Polyethylene and polypropylene have no sulphur, so you get zero sulphur diesel,” says Ramesh.
Both Holm and Ramesh have a single-word answer when asked where they want to see the technology in five or ten years: “Everywhere!”
Reactors could be mounted on boats, so that any plastics scooped out of the water could be fed straight in to provide diesel fuel, to be used on board or to sell. A truck with a reactor mounted on the back could drive around small communities processing plastic where it is collected. Ramesh points out that refuse collection trucks, in the US at least, average around 3 miles per gallon of fuel. They are currently in discussions with local waste management firms with a view to diverting waste plastic they collect to fuel for the refuse trucks.
Of course, one of the beauties of the technology is that if this kind of local conversion takes off, the project could prevent plastics from getting into the ocean in the first place.
A 200 lb/d reactor is the optimum size for heat transfer, but Ramesh says this could be scaled up to 2,000 lb/d within six months.
“This is going to be a continuous process. If we have five reactors, we can do 10,000 lb/d. This is business sense. At this scale you can get your investment back within 18 months. If you have a 2,000 lb/d reactor you would need up to five years. We are balancing the business aspect and the technological aspect,” says Ramesh, adding: “The municipalities can use it as a revenue source instead of paying money to send it landfill.”
Holm says that as the plastic pollution problem took 60 years to create, it is “arrogant and misguided” to suggest that it could be solved in less time than that.
“We’re so happy that we’re bringing encouragement to people that there are solutions,” says Holm. “We’re not telling anybody that we have the one single solution, but we pretty firmly believe that plastic-to-fuel conversion can be a very valuable part of an overall response. It’s going to take every one of these ideas, some crazier than others, and we’re going to have to investigate them all and give each other credit for every effort to do the right thing.”
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