Energy frontiers

Graphene is an emerging material composed of two-dimensional honeycomb formation of carbon atoms. Graphene thin films are beginning to revolutionize the electronics industry due to their unique and favorable properties. But graphene can also form a composite thin film called graphene oxide (GO) that has remarkable water transport properties: water can easily flow through the GO film while helium and other substances cannot. GO films are unconventional water valves. This unusual property is being exploited for water purification and desalination, but it also has a related use: synthetic tree leaves. The structure of graphene oxide is so similar to tree leaves that researchers at NAU have decided to make synthetic leaves using only GO films. Tree leaves have several functions. First, water evaporates from their surfaces and draws more water up through the tree; they act as mini water pumps. Second, when water evaporates from tree leaves, the surrounding air is cooled; leaves act as air conditioners. Thus, synthetic GO leaves will be both water pumps capable of moving water to great heights, and air conditioners capable of cooling building. Imagine a skyscraper in Phoenix that is cooled only with synthetic GO tree leaves or an irrigation system that requires no mechanical pumps. Currently, NAU researchers are designing and building “trees” made entirely of synthetic materials for applications in building design, agriculture and many other areas.

NAU researcher Dr. Michael Shafer researched the application of small-scale energy harvesting from animal movements to assist biologists with the tracking and monitoring of wildlife. According to Dr. Shafer, he is “trying to take energy that’s all around us – differences in temperature, mechanical energy, kinetic energy – and convert it into something useful.” He has helped with the development of an ultra-lightweight device that generates power through the flapping of a bird’s wings. This is made possible by the use of piezoelectric material that produces electricity when force is applied.

Dr. Michael Shafer is currently developing devices to harness energy as marine animals swim and dive in the ocean. This energy would be used to power sensor-laden animal tags. Ambient energy sources such as fluid-kinetic and hydrostatic pressure fluctuations are also researched in Dr. Shafer’s lab. Harvesting energy on animals to track their location or collect sensor measurements has potential impacts in ocean and climate science, marine biology, and other fields. The increased available energy of the animal tags would prolong the devices’ lifetimes, allowing for more data collection on climate, location, salinity, and more.

In 2012-2013, undergraduate Adam Nelessen worked with NREL on an honors thesis modeling wave-energy harvesting devices. With guidance from collaborators at NREL, Adam used SimMechanics to develop a power prediction model for devices harvesting energy in ocean environments. He continued his research in an internship at NREL following his graduation in 2013.