Engineering

Engineering Sustainable Solutions in Energy and the Environment

Moule LabToday’s world is largely dependent upon non-renewable and environmentally damaging sources of energy. Powering our future will require replacing many current technologies, transforming the largest industries in the world, tapping a vast array of renewable sources, and changing behavior. Meeting this energy challenge and protecting the environment requires solutions that span policy, science and technology.

College of Engineering faculty are recognized leaders in research and innovation in energy efficiency, biomass, wind, alternative fuels and hybrid vehicles, as well as environmental problems related to water, wastewater, air and soil. They approach these issues from an integrated perspective, made possible by the breadth of our programs, a highly interdisciplinary academic culture, key research faculty and our geographic location.

Current research impacts the wide range of factors that contribute to quality of life. For example:

Stopping a devastating citrus disease before it’s too late

The Asian citrus psyllid, an aphid-sized insect, can carry a bacterium fatal to citrus trees. Florida citrus growers are already seeing their $9 billion industry affected to the point that many of their processing plants and packing facilities have been shut down for lack of product.

Cristina Davis, a researcher in the Department of Mechanical and Aerospace Engineering, collaborating with Abhaya Dandekar in Plant Sciences and Oliver Fiehn at the Genome Center is helping the California citrus industry fight this destructive disease before it’s too late. They have devised a sensor or mechanical sniffer that can diagnose the difference between a sick tree and a healthy one by identifying volatile organic compounds that are off-gassed by infected trees. This disease is a silent killer; While trees don’t show symptoms for 5-8 years, they are contagious. By treating or removing a tree that is infected before it spreads the disease to the entire grove, growers can take defensive action using diagnostic tools developed at UC Davis.

Converting food and other green wastes into energy

Californians create nearly 3,000 pounds of household garbage and industrial waste every second, some 90 million tons a year, with about half of it going to landfills. Meanwhile, the state and the nation are searching for ways to reduce our dependence on fossil fuels by developing alternative fuel sources.

Technology invented by Ruihong Zhang, professor of biological and agricultural engineering, can harvest energy from this vast untapped resource, turning food and other green wastes into hydrogen and methane gases that can be used to power California homes. The Biogas Energy Project is the first large-scale demonstration in the United States of technology that can produce enough energy from one ton of biomass to power ten California homes for one day. The technology, called an “anaerobic phased solids digester,” has been licensed from the university and adapted for commercial use by Onsite Power Systems Inc.

Setting the bar for air quality standards

Air pollution poses a serious threat—to the physical health of people everywhere, to our economic vitality amidst rising energy and medical costs and to the long-term well being of the planet through global climate change. Despite progress made by clean air efforts in the U.S. and abroad, more must be done.

Dan Sperling, director of the Institute of Transportation Studies and a professor in civil and environmental engineering, and Bryan Jenkins, professor of biological and agricultural engineering, were among four UC experts commissioned by California Governor Schwarzenegger to write the world’s first air quality standard to reduce carbon emissions from transportation fuels. This carbon emissions fuel standard offers a blue print for national and international change.

Making solar energy cheaper and more flexible

An area about the size of Texas—some 250,000 square miles—covered with solar cells, could satisfy all the world’s energy needs. But while today’s solar cells are close to the theoretical maximum efficiency, they are about six times as expensive as fossil fuels.

Plastic solar cells produced from organic semiconductors offer the potential for efficient solar energy with low-cost fabrication.

Adam Moule, an assistant professor in the Department of Chemical Engineering and Materials Science, is working on the next generation of solar cells that will be light, flexible, attractive and most importantly, cheap. Their flexible lightweight properties will allow them to be deployed over a wide range of new applications and many kinds of surfaces, so that they can generate energy where it is needed and used.

Unlocking an endless energy source

Nuclear fusion, the process that powers the sun and other stars, if duplicated in a controlled way on Earth, could solve our energy problems, providing all the power we could ever use for billions of years—essentially the lifetime of the planet.

Professor David Hwang, in the Department of Applied Science, focuses on the two most promising areas of controlled thermo-nuclear fusion: magnetic and inertial confinement nuclear fusion.

In simple terms, nuclear fusion employs isotopes of hydrogen, the most abundant element on the planet, to create energy. Deuterium and tritium will, under extreme heat, shed electrons and other particles so that some of their stripped down atomic nuclei fuse together. In the process, tremendous amounts of energy are released. That’s what Albert Einstein was talking about when he said E=mc2, or energy equals mass in grams times the square of the speed of light.

Magnetic nuclear fusion traps this reaction inside a kind of container made of magnetic fields. Inertial fusion employs laser energy to blast the fuel source, compressing it, creating heat, forcing fusion and releasing energy.

The challenge, however, is containing the high temperature reactions. Moreover, for fusion energy to be a reasonable power source, the technology must produce more energy than it consumes.

Success in this high energy, high stakes research could provide endless supplies of energy with no risk of nuclear accident or air pollution and leave minimal nuclear waste.

Advancing knowledge about global climate change

Carbon dioxide is a key green house gas, trapping solar radiation and affecting the temperature on Earth. The planet’s natural carbon cycle maintains a balance between emitted and absorbed CO2. Since the advent of the industrial revolution in the 18th Century, with the burning of fossil fuels, the global concentrations of CO2 have increased by 35 percent, as have concerns about the devastating long-term effects of resulting global climate change.

Steps to mitigating global warming through the greenhouse effect will likely include extracting carbon dioxide from power plant flues and the atmosphere and storing it underground, initially as a dense gas in old mines and depleted oil reservoirs that would eventually turn into solid, stable calcium carbonate through chemical reactions.

Calcium carbonate, the major long-term sink for atmospheric carbon dioxide is found in several forms on Earth, in limestone, shellfish and beautiful calcite crystals locked underground.

Chemical engineering and materials science professor Alexandra Navrotsky and her colleagues at UC Davis’ Peter A. Rock Thermochemistry Laboratory have measured with high accuracy the heat lost or gained as calcium carbonate changes from one form to another. In findings published in the journal Proceedings of the National Academy of Sciences, the research team has contributed to a better understanding of the chemical reactions and transformations that occur in the cycle from least to most stable forms of calcium carbonate. By advancing knowledge about this important mechanism, such research contributes to our ability to intervene meaningfully in global climate change.