An essential principle of sustainability addresses the reality that the earth’s resources, which provide basic necessities such as water, heat and shelter — not to mention luxuries such as electricity and fuel for automobiles — are not infinite and perpetually giving. They aren’t even abundant, in an economically feasible sense. For example, most of the earth’s remaining oil reserves will be difficult — and therefore extremely expensive — to physically access and exploit. Water is no different. As our insatiable thirst for it rapidly drains aquifers, millions of people in developing countries must walk half a mile or more to reach water fit to drink or bathe in, and tens of thousands of people die from water-borne illnesses every day.
So what can be done to slow down or reverse this trend? How can current generations ensure that future ones are left with enough water to drink, enough fuel to heat homes and enough materials to build those homes? One thing is certain: To conserve natural resources and preserve a similar quality of life for future generations, humans today must change their behavior. In short, we must pollute less, waste less and consume less.
But more can be done. On the production end, the sustainability movement challenges researchers to design and build efficient, less wasteful and clean — or “green” — products and processes. As a fundamentally applied science, engineering has a huge responsibility in this endeavor. In fact, some professionals argue that good design is inherently sustainable.
“Sustainability, in the larger sense, is supposed to infuse everything we do as engineers — it’s always been that way,” said Kevin Hall, professor and head of the department of civil engineering. “As the world’s needs change, engineering practices change with it. It just makes a lot of sense that what we design and build now can be sustained — not to become obsolete and disposed of at some point. For engineers, it’s about how we use technology to extend the life of products and restore, renew and reuse natural resources to meet society’s needs over the long run.”
At the College of Engineering, sustainability has been a strategic goal and point of emphasis for many years, maybe a full decade before the university declared sustainability a priority. The issue pervades labs and class-rooms. These researchers lead the way.
Improving Chemical Extraction With “Friendly” Natural Processes
Chemical engineering researcher Jerry King, top, Julie Carrier, center, and Ed Clausen use clean and “green” processes to extract various products from fluids.
Working with “green” fluids instead of chemicals, several researchers pursue projects that use an earth-friendly “critical fluid technology” to extract added-value products from foods before they are consumed or crops before they are converted to biofuels such as ethanol. Jerry King, holder of the Ansel and Virginia Condray Endowed Professorship in Biochemical and Chemical Separations, is one of the pioneers of critical fluid technology, a “green” process that uses water or carbon dioxide gas at high temperatures and high pressures to extract substances from biomass.
The process can remove caffeine from coffee, fat from meat and pesticides from fruits and vegetables. It also can replace the use of organic solvents, which result in expensive hazardous waste and often leave a chemical residue in the products.
“We’ve been working on this for a lot longer than ‘sustainability’ has been a catchword,” King said. “But it fits right in. We are going to use nature and give back to nature.”
With support from the U.S. Department of Agriculture, King and Luke Howard, professor of food science, extract antioxidant products from grapes. Human use of antioxidants is popular as a dietary supplement in fighting coronary artery disease, some cancers, Alzheimer’s disease and some forms of arthritis. Researchers in King’s lab have the capability to extract antioxidants and other products from a variety of other crops and convert the left-over residues into high-value, bio-renewable products.
Another aspect of King’s research involves coupling the green processing agents in consecutive extraction-reaction steps for the conversion of biomass and industrial waste products into fuels and higher-value chemicals. Collaborating with research teams in Japan, Germany and Great Britain, he is using compressed water and carbon dioxide with “natural” enzymes to produce feedstocks for the production of bioethanol and biodiesel as well as other chemicals. This to make biofuel production a cost-feasible enterprise, since the cost of fossil fuels — even at their rising price — remains cheaper. In research similar to King’s, Julie Carrier, associate professor of biological and agricultural engineering, and Ed Clausen, the Ray C. Adam Endowed Chair in Chemical Engineering, combined their primary areas of study in a possible solution for the biofuel economic equation. Carrier’s work concentrates on extraction of added-value products using critical fluid technology, and Clausen’s work concentrates on converting crops to biofuels.
They work with switchgrass, a plant that grows tall and in abundance, which makes it a good biofuel crop. Carrier and Clausen have successfully used water to extract antioxidants from switchgrass. Their studies have shown the extraction process leaves no measurable loss of energy potential when the crop is later converted to cellulose ethanol.
“Instead of just throwing away a product, which would not get used, we’re getting some additional value products,” Clausen said.
Converting Chicken Fat and Tall Oil Fatty Acid Into Biodiesel
Other chemical engineering researchers, supported by the Mack-Blackwell Rural Transportation Center, make biodiesel, a “green” fuel, out of low-cost feedstocks and other agricultural by-products. Buddy Babcock, professor of chemical engineering, Clausen, and Michael Popp, associate professor of agricultural economics, have supervised two graduate students, Brian Mattingly and Brent Schulte, who successfully converted chicken fat into biodiesel fuel. Schulte also converted tall-oil fatty acid, a major by-product of the wood-pulping process.
Both projects illustrated that in light of rising petroleum diesel costs, biodiesel can be economically competitive as long as feedstock prices are not prohibitive. Babcock said his students’ work could lead oil companies and energy producers to seriously consider combining petroleum-based diesel with a biodiesel product made out of crude and inexpensive feedstocks.
Sustainability is the recognition of the moral obligation that future generations’ prosperity should not be sacrificed for short-term gain today. –Greg Thoma, professor of chemical engineering, College of Engineering
Students Joel Vincent and Brian Mattingly and chemical engineering professor Buddy Babcock convert feedstocks into biodiesel.
“We’re trying to expand the petroleum base,” Mattingly said. “Even 5 to 20 percent blending of biodiesel into petroleum-based diesel significantly reduces our dependence on foreign oil, and, perhaps equally important, we’re using a renewable resource. These are just a few of biodiesel’s benefits.”
For anyone concerned about air quality and global warming, the thought of using fat from chicken parts to power automobiles that emit less pollution is exciting. Because biodiesel is derived from renewable feedstocks such as plant oils or animal fats, it is better for the environment than purely petroleum-based products. As Mattingly mentioned, it is renewable; it also is biodegradable and thus a carbon-neutral material, so it does not contribute to greenhouse gases. In fact, it decreases sulfur and particulate-matter emissions.
“In addition to being a renewable, biodegradable and carbon-neutral fuel source, biodiesel can be formed in a matter of months from feedstocks produced locally,” Schulte said. “This process promotes a more sustainable energy infrastructure and creates new labor and market opportunities for domestic crops.”
In the first study, Mattingly worked with high-quality fat — chicken fat with a free fatty acid content less than 2 percent — and low-quality, feed-grade fat — fat with as much as 6 percent free fatty acid content. He subjected each grade of chicken fat to a one-step and multiple-step conversion process and discovered that free fatty acid content is the most important factor to consider for producing biodiesel using these two catalyzed processes. Both produced biodiesel fuel, but the single-step process could not convert free fatty acids into fuel.
Building on Mattingly’s findings, Schulte jettisoned traditional, catalyzed conversion methods and instead subjected low-grade chicken fat and tall-oil fatty acid to supercritical methanol treatment, a chemical process similar to that used by Jerry King, who helped Schulte on the project. The treatment causes a reaction between methanol and feedstock components — in this case, chicken fat and tall oil — by subjecting the by-products to high temperature and pressure. In contrast to conventional methods of converting feedstocks into biodiesel, supercritical methanol treatment is a simple, one-step process that does not require a catalyst. Schulte produced biodiesel yields in excess of 89 percent from chicken fat and 94 percent from tall-oil fatty acid. The new method also avoided undesired production of soaps during processing
Making Electric Energy More Efficient and Accessible
Projects led by electrical-engineering researchers Juan Balda, top, Roy McCann, center, and Hameed Naseem, bottom, focus on developing effective and alternative sources of electrical power.
Energy is the lifeline of the industrialized world and the foundation of a high standard of living. Most energy comes from fossil fuels, a finite source that, when burned, also is harmful to the environment. Less than 10 percent of current energy resources are renewable. Meanwhile, the demand grows at an exponential rate. Researchers in the department of electrical engineering are working in several areas to address what is perceived to be, from a sustainability viewpoint, an amassing energy crisis.
At the university’s National Center for Reliable Electric Power Transmission, Juan Carlos Balda, professor of electrical engineering, develops power-electronics interfaces for renewable energy sources and solutions. Referred to as “Combined Heat and Power,” the project investigates power-electronics interfaces for systems like microturbines, which use wasted heat to generate electric power. For instance, heat from an industrial furnace can be channeled to a system of microturbines to generate new power. In Balda’s project, this “recycling” of energy, along with the use of renewable energy sources such as a wind-powered generator or a photovoltaic array, make use of power electronics to interface with the power grid. Ideally, an industrial facility exploiting renewable energy sources and wasted heat could generate most, if not all, of its required electric power. In some cases excess power could be sold to the local electric utility.
Roy McCann, associate professor of electrical engineering, is developing a new type of generator that is more efficient in producing electric power. It uses a fundamentally new method of designing and operating electric motors and generators by embedding magnetic field, micro-electromechanical sensors inside the motor. The system includes rotating components that directly monitor and adjust the operation to maintain a maximized level of electrical efficiency.
Existing generator technologies rely on taking a few external measurements such as voltage, speed and current. Recent advances in permanent magnet materials and electrical steels have improved energy efficiency. However, maximum efficiencies are possible only by knowing the instantaneous magnetic fields inside the generator. The inclusion of embedded sensors and control techniques developed from this research enables these energy-efficiency gains to be achieved by providing the required information from internal magnetic fields. This work also benefits electric motor efficiency, which is important for electric and hybrid-electric vehicle propulsion, which also reduces dependency on fossil fuels.
Because conventional energy resources are limited and harmful to the environment, scientists and engineers are focusing on green alternatives, such as wind and solar power. The latter is beneficial because its source is practically infinite, and it can be generated at the point of use, so it does not depend on a power grid. Furthermore, with solar power, there is no loss of energy in transmission; it converts directly into electricity. Perhaps most importantly, it is harmless to the environment.
In his lab, Hameed Naseem, professor of electrical engineering, is trying to make solar energy practical and feasible. Naseem has spent much of his career developing solar cells. His current work focuses on the refinement and improvement of solar cells for a process called photovoltaic power generation, which uses semiconductors and solar cells constructed of silicon, the second-most abundant material in the earth’s crust.
Latest improvements include the development of thinner, less expensive types of silicon wafers and films that absorb more light, Naseem said. His patented method uses a low-temperature process of metal-induced crystallization, which is superior to older, high-temperature process methods that cause a wafer “bowing” problem.
Minimizing the Environmental Impact of the Fayetteville Shale Play
For the past several years, there’s been a lot of talk about the Fayetteville Shale Play, an unconventional natural gas formation across central Arkansas. Now, two large natural-gas production companies have begun exploration and production of the play, and many smaller companies will likely follow. Economists and business forecasters have predicted that extraction and recovery of natural gas from the play will contribute significantly to Arkansas’ economy. But this project does not come without environmental costs. As with any subsurface resource extraction, significant development of surface infrastructure is required, which has the potential to cause localized environmental disturbances.
Led by Greg Thoma, professor of chemical engineering, a diverse team of engineering and geospatial researchers is working to keep this impact to a minimum. With aid from the U.S. Department of Energy, Thoma is collaborating with researchers at the University of Arkansas Center for Advanced Spatial Technologies (CAST) and Argonne National Laboratory to develop a Web-based, decision-support tool that energy companies can use to plan for development that minimizes adverse effects on sensitive ecosystems. The researchers’ work will serve as a model for the application of a proactive approach to reduce and manage risks associated with the exploration and production of unconventional natural gas resources in the United States.
Specifically, the researchers are developing Web-based application modules that identify areas sensitive to disturbance, so risks can be minimized in advance, or areas can be avoided altogether. Thoma’s team is building three-dimensional maps of the geographical area of the play with underlying databases including important environmental and cultural features. For example, they are gathering information from state and federal regulatory agencies about sensitive watersheds and habitats in the area. With this information and CAST’s powerful mapping tools, the decision-support system will provide important information early in the development process so that, where possible, development can be located away from sensitive areas.
“Many times, this simply means building an access road or locating a well just a few hundred yards from the proposed site,” Thoma said. “These shifts can make a significant difference in terms of limiting runoff into streams or threatening wildlife habitat, such as a nesting area.”
When finished, the multipurpose system will serve as a type of clearinghouse of information and thus will educate the general public about the play and the process of extracting natural gas from it. The life cycle of a lease will be explained in detail, which will help the public understand stages of operation and industry’s commitment to environmental stewardship. The online system also will facilitate communication among all stakeholders, including government, regulatory officials and industry representatives. Communication among the stakeholders will foster an atmosphere of cooperation that should result in early identification of potential problems that can be jointly resolved in a way that protects the environment without unnecessary delays to development of the play.
“We’ve made significant progress, but we have a lot of work ahead of us,” Thoma said. “With time, I think we’ll have a tool that all stakeholders will be happy with, and one that will help to conserve and preserve these ecosystems.”
Other Sustainability Research in Engineering
Up and down the halls of Bell Engineering Center and the Engineering Building, out at the Arkansas Research and Technology Park, on the shores of Beaver Lake, at neighborhoods in Rogers and Fayetteville and even in remote villages of Central and South America, many other engineering research projects focus on sustainable processes and design. These investigations tackle stream restoration, “human ecosystems,” low-impact development, water-filtration systems and decision-support tools to mitigate negative environmental impact. In addition to serving residents of Arkansas and the world, these projects, in some cases, may save lives. Go to the links below to read about these projects in previous issues of Research Frontiers.