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Tuesday, April 9th, 2019
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| 12:00a |
Engineers develop concept for hybrid heavy-duty trucks Heavy-duty trucks, such as the 18-wheelers that transport many of the world’s goods from farm or factory to market, are virtually all powered by diesel engines. They account for a significant portion of worldwide greenhouse gas emissions, but little has been done so far to curb their climate-change-inducing exhaust.
Now, researchers at MIT have devised a new way of powering these trucks that could drastically curb pollution, increase efficiency, and reduce or even eliminate their net greenhouse gas emissions.
The concept involves using a plug-in hybrid engine system, in which the truck would be primarily powered by batteries, but with a spark ignition engine (instead of a diesel engine). That engine, which would allow the trucks to conveniently travel the same distances as today’s conventional diesel trucks, would be a flex-fuel model that could run on pure gasoline, pure alcohol, or blends of these fuels.
While the ultimate goal would be to power trucks entirely with batteries, the researchers say, this flex-fuel hybrid option could provide a way for such trucks to gain early entry into the marketplace by overcoming concerns about limited range, cost, or the need for excessive battery weight to achieve longer range.
The new concept was developed by MIT Energy Initiative and Plasma Fusion and Science Center research scientist Daniel Cohn and principal research engineer Leslie Bromberg, who are presenting it at the annual SAE International conference on April 11.
“We’ve been working for a number of years on ways to make engines for cars and trucks cleaner and more efficient, and we’ve been particularly interested in what you can do with spark ignition [as opposed to the compresson ignition used in diesels], because it’s intrinsically much cleaner,” Cohn says. Compared to a diesel engine vehicle, a gasoline-powered vehicle produces only a tenth as much nitrogen oxide (NOx) pollution, a major component of air pollution.
In addition, by using a flex-fuel configuration that allows it to run on gasoline, ethanol, methanol, or blends of these, such engines have the potential to emit far less greenhouse gas than pure gasoline engines do, and the incremental cost for the fuel flexibility is very small, Cohn and Bromberg say. If run on pure methanol or ethanol derived from renewable sources such as agricultural waste or municipal trash, the net greenhouse gas emissions could even be zero. “It’s a way of making use of a low-greenhouse-gas fuel” when it’s available, “but always having the option of running it with gasoline” to ensure maximum flexibility, Cohn says.
While Tesla Motors has announced it will be producing an all-electric heavy-duty truck, Cohn says, “we think that’s going to be very challenging, because of the cost and weight of the batteries” needed to provide sufficient range. To meet the expected driving range of conventional diesel trucks, Cohn and Bromberg estimate, would require somewhere between 10 and 15 tons of batteries “That’s a significant fraction of the payload” such a truck could otherwise carry, Cohn says.
To get around that, “we think that the way to enable the use of electricity in these vehicles is with a plug-in hybrid,” he says. The engine they propose for such a hybrid is a version of one the two researchers have been working on for years, developing a highly efficient, flexible-fuel gasoline engine that would weigh far less, be more fuel-efficient, and produce a tenth as much air pollution as the best of today’s diesel-powered vehicles.
Cohn and Bromberg did a detailed analysis of both the engineering and the economics of what would be needed to develop such an engine to meet the needs of existing truck operators. In order to match the efficiency of diesels, a mix of alcohol with the gasoline, or even pure alcohol, can be used, and this can be processed using renewable energy sources, they found. Detailed computer modeling of a whole range of desired engine characteristics, combined with screening of the results using an artificial intelligence system, yielded clear indications of the most promising pathways and showed that such substitutions are indeed practically and financially feasible.
In both the present diesel and the proposed flex-fuel vehicles, the emissions are measured at the tailpipe, after a variety of emissions-control systems have done their work in both cases, so the comparison is a realistic measure of real-world emissions. The combination of a hybrid drive and flex-fuel engine is “a way to enable the introduction of electric drive into the heavy truck sector, by making it possible to meet range and cost requirements, and doing it in a way that’s clean,” Cohn says.
Bromberg says that gasoline engines have become much more efficient and clean over the years, and the relative cost of diesel fuel has gone up, so that the cost advantages that led to the near-universal adoption of diesels for heavy trucking no longer prevail. “Over time, gas engines have become more and more efficient, and they have an inherent advantage in producing less air pollution,” he says. And by using the engine in a hybrid system, it can always operate at its optimum speed, maximizing its efficiency.
Methane is an extremely potent greenhouse gas, so if it can be diverted to produce a useful fuel by converting it to methanol through a simple chemical process, “that’s one of the most attractive ways to make a clean fuel,” Bromberg says. “I think the alcohol fuels overall have a lot of promise.”
Already, he points out, California has plans for new regulations on truck emissions that are very difficult to meet with diesel engine vehicles. “We think there’s a significant rationale for trucking companies to go to gasoline or flexible fuel,” Cohn says. “The engines are cheaper, exhaust treatment systems are cheaper, and it’s a way to ensure that they can meet the expected regulations. And combining that with electric propulsion in a hybrid system, given an ever-cleaner electric grid, can further reduce emissions and pollution from the trucking sector.”
Pure electric propulsion for trucks is the ultimate goal, but today’s batteries don’t make that a realistic option yet, Cohn says: “Batteries are great, but let’s be realistic about what they can provide.”
And the combination they propose can address two major challenges at once, they say. “We don’t know which is going to be stronger, the desire to reduce greenhouse gases, or the desire to reduce air pollution.” In the U.S., climate change may be the bigger push, while in India and China air pollution may be more urgent, but “this technology has value for both challenges,” Cohn says.
The research was supported by the MIT Arthur Samberg Energy Innovation Fund. | | 11:00a |
MIT spinout seeks to transform food safety testing “This is a $10 billion market and everyone knows it.” Those are the words of Chris Hartshorn, CEO of a new MIT spinout — Xibus Systems — that is aiming to make a splash in the food industry with their new food safety sensor.
Hartshorn has considerable experience supporting innovation in agriculture and food technology. Prior to joining Xibus, he served as chief technology officer for Callaghan Innovation, a New Zealand government agency. A large portion of the country’s economy relies upon agriculture and food, so a significant portion of the innovation activity there is focused on those sectors.
While there, Hartshorn came in contact with a number of different food safety sensing technologies that were already on the market, aiming to meet the needs of New Zealand producers and others around the globe. Yet, “every time there was a pathogen-based food recall” he says, “it shone a light on the fact that this problem has not yet been solved.”
He saw innovators across the world trying to develop a better food pathogen sensor, but when Xibus Systems approached Hartshorn with an invitation to join as CEO, he saw something unique in their approach, and decided to accept.
Novel liquid particles provide quick indication of food contamination
Xibus Systems was formed in the fall of 2018 to bring a fast, easy, and affordable food safety sensing technology to food industry users and everyday consumers. The development of the technology, based on MIT research, was supported by two commercialization grants through the MIT Abdul Latif Jameel Water and Food Systems Lab’s J-WAFS Solutions program. It is based on specialized droplets — called Janus emulsions — that can be used to detect bacterial contamination in food. The use of Janus droplets to detect bacteria was developed by a research team led by Tim Swager, the John D. MacArthur Professor of Chemistry, and Alexander Klibanov, the Novartis Professor of Biological Engineering and Chemistry.
Swager and researchers in his lab originally developed the method for making Janus emulsions in 2015. Their idea was to create a synthetic particle that has the same dynamic qualities as the surface of living cells.
The liquid droplets consist of two hemispheres of equal size, one made of a blue-tinted fluorocarbon and one made of a red-tinted hydrocarbon. The hemispheres are of different densities, which affects how they align and how opaque or transparent they appear when viewed from different angles. They are, in effect, lenses. What makes these micro-lenses particularly unique, however, is their ability to bind to specific bacterial proteins. Their binding properties enabled them to move, flipping from a red hemisphere to blue based on the presence or absence of a particular bacteria, like Salmonella.
“We were thrilled by the design,” Swager says. “It is a completely new sensing method that could really transform the food safety sensing market. It showed faster results than anything currently available on the market, and could still be produced at very low cost.”
Janus emulsions respond exceptionally quickly to contaminants and provide quantifiable results that are visible to the naked eye or can be read via a smartphone sensor.
“The technology is rooted in very interesting science,” Hartshorn says. “What we are doing is marrying this scientific discovery to an engineered product that meets a genuine need and that consumers will actually adopt.”
Having already secured nearly $1 million in seed funding from a variety of sources, and also being accepted into Sprout, a highly respected agri-food accelerator, they are off to a fast start.
Solving a billion-dollar industry challenge
Why does speed matter? In the field of food safety testing, the standard practice is to culture food samples to see if harmful bacterial colonies form. This process can take many days, and often can only be performed offsite in a specialized lab.
While more rapid techniques exist, they are expensive and require specialized instruments — which are not widely available — and still typically require 24 hours or more from start to finish. In instances where there is a long delay between food sampling and contaminant detection, food products could have already reached consumers hands — and upset their stomachs. While the instances of illness and death that can occur from food-borne illness are alarming enough, there are other costs as well. Food recalls result in tremendous waste, not only of the food products themselves but of the labor and resources involved in their growth, transportation, and processing. Food recalls also involve lost profit for the company. North America alone loses $5 billion annually in recalls, and that doesn’t count the indirect costs associated with the damage that occurs to particular brands, including market share losses that can last for years.
The food industry would benefit from a sensor that could provide fast and accurate readings of the presence and amount of bacterial contamination on-site. The Swager Group’s Janus emulsion technology has many of the elements required to meet this need and Xibus Systems is working to improve the speed, accuracy, and overall product design to ready the sensor for market.
Two other J-WAFS-funded researchers have helped improve the efficiency of early product designs. Mathias Kolle, assistant professor in the Department of Mechanical Engineering at MIT and recipient of a separate 2017 J-WAFS seed grant, is an expert on optical materials. In 2018, he and his graduate student Sara Nagelberg performed the calculations describing light’s interaction with the Janus particles so that Swager’s team could modify the design and improve performance. Kolle continues to be involved, serving with Swager on the technical advisory team for Xibus.
This effort was a new direction for the Swager group. Says Swager: “The technology we originally developed was completely unprecedented. At the time that we applied to for a J-WAFS Solutions grant, we were working in new territory and had minimal preliminary results. At that time, we would have not made it through, for example, government funding reviews which can be conservative. J-WAFS sponsorship of our project at this early stage was critical to help us to achieve the technology innovations that serve as the foundation of this new startup.”
Xibus co-founder Kent Harvey — also a member of the original MIT research team—is joined by Matthias Oberli and Yuri Malinkevich. Together with Hartshorn they are working on a prototype for initial market entry. They are actually developing two different products: a smartphone sensor that is accessible to everyday consumers, and a portable handheld device that is more sensitive and would be suitable for industry. If they are able to build a successful platform that meets industry needs for affordability, accuracy, ease of use, and speed, they could apply that platform to any situation where a user would need to analyze organisms that live in water. This opens up many sectors in the life sciences, including water quality, soil sensing, veterinary diagnostics, as well as fluid diagnostics for the broader healthcare sector.
The Xibus team wants to nail their product right off the bat.
“Since food safety sensing is a crowded field, you only get one shot to impress your potential customers,“ Hartshorn says. “If your first product is flawed or not interesting enough, it can be very hard to open the door with these customers again. So we need to be sure our prototype is a game-changer. That’s what’s keeping us awake at night.” | | 11:19a |
Shrinking the carbon footprint of a chemical in everyday objects The biggest source of global energy consumption is the industrial manufacturing of products such as plastics, iron, and steel. Not only does manufacturing these materials require huge amounts of energy, but many of the reactions also directly emit carbon dioxide as a byproduct.
In an effort to help reduce this energy use and the related emissions, MIT chemical engineers have devised an alternative approach to synthesizing epoxides, a type of chemical that is used to manufacture diverse products, including plastics, pharmaceuticals, and textiles. Their new approach, which uses electricity to run the reaction, can be done at room temperature and atmospheric pressure while eliminating carbon dioxide as a byproduct.
“What isn’t often realized is that industrial energy usage is far greater than transportation or residential usage. This is the elephant in the room, and there has been very little technical progress in terms of being able to reduce industrial energy consumption,” says Karthish Manthiram, an assistant professor chemical engineering and the senior author of the new study.
The researchers have filed for a patent on their technique, and they are now working on improving the efficiency of the synthesis so that it could be adapted for large-scale, industrial use.
MIT postdoc Kyoungsuk Jin is the lead author of the paper, which appears online April 9 in the Journal of the American Chemical Society. Other authors include graduate students Joseph Maalouf, Nikifar Lazouski, and Nathan Corbin, and postdoc Dengtao Yang.
Ubiquitous chemicals
Epoxides, whose key chemical feature is a three-member ring consisting of an oxygen atom bound to two carbon atoms, are used to manufacture products as varied as antifreeze, detergents, and polyester.
“It’s impossible to go for even a short period of one’s life without touching or feeling or wearing something that has at some point in its history involved an epoxide. They’re ubiquitous,” Manthiram says. “They’re in so many different places, but we tend not to think about the embedded energy and carbon dioxide footprint.”
Several epoxides are among the chemicals with the top carbon footprints. The production of one common epoxide, ethylene oxide, generates the fifth-largest carbon dioxide emissions of any chemical product.
Manufacturing epoxides requires many chemical steps, and most of them are very energy-intensive. For example, the reaction used to attach an atom of oxygen to ethylene, producing ethylene oxide, must be done at nearly 300 degrees Celsius and under pressures 20 times greater than atmospheric pressure. Furthermore, most of the energy used to power this kind of manufacturing comes from fossil fuels.
Adding to the carbon footprint, the reaction used to produce ethylene oxide also generates carbon dioxide as a side product, which is released into the atmosphere. Other epoxides are made using a more complicated approach involving hazardous peroxides, which can be explosive, and calcium hydroxide, which can cause skin irritation.
To come up with a more sustainable approach, the MIT team took inspiration from a reaction known as water oxidation, which uses electricity to split water into oxygen, protons, and electrons. They decided to try performing the water oxidation and then attaching the oxygen atom to an organic compound called an olefin, which is a precursor to epoxides.
This was a counterintuitive approach, Manthiram says, because olefins and water normally cannot react with each other. However, they can react with each other when an electric voltage is applied.
To take advantage of this, the MIT team designed a reactor with an anode where water is broken down into oxygen, hydrogen ions (protons), and electrons. Manganese oxide nanoparticles act as a catalyst to help this reaction along, and to incorporate the oxygen into an olefin to make an epoxide. Protons and electrons flow to the cathode, where they are converted into hydrogen gas.
Thermodynamically, this reaction only requires about 1 volt of electricity, less than the voltage of a standard AA battery. The reaction does not generate any carbon dioxide, and the researchers anticipate that they could further reduce the carbon footprint by using electricity from renewable sources such as solar or wind to power the epoxide conversion.
Scaling up
So far, the researchers have shown that they can use this process to create an epoxide called cyclooctene oxide, and they are now working on adapting it to other epoxides. They are also trying to make the conversion of olefins into epoxides more efficient — in this study, about 30 percent of the electrical current went into the conversion reaction, but they hope to double that.
They estimate that their process, if scaled up, could produce ethylene oxide at a cost of $900 per ton, compared to $1,500 per ton using current methods. That cost could be lowered further as the process becomes more efficient. Another factor that could contribute to the economic viability of this approach is that it also generates hydrogen as a byproduct, which is valuable in its own right to power fuel cells.
The researchers plan to continue developing the technology in hopes of eventually commercializing it for industrial use, and they are also working on using electricity to synthesize other kinds of chemicals.
“There are many processes that have enormous carbon dioxide footprints, and decarbonization can be driven by electrification,” Manthiram says. “One can eliminate temperature, eliminate pressure, and use voltage instead.”
The research was funded by MIT’s Department of Chemical Engineering and a National Science Foundation Graduate Research Fellowship. |
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