Ocean: A renewable energy source
By Hams Laeeq and Yuanrong Han
Wouldn’t it be nice to have a clean source of energy located just a few miles from where you live that can also run 24/7? Assistant professor of mechanical engineering Reza Alam asked a similar question when thinking about harnessing ocean wave energy.
Prof. Alam and his team of researchers at UC Berkeley have successfully designed a machine to make electricity out of ocean waves with great efficiency. Although more work is being done to perfect the technology, it won’t be too long before it can be used commercially.
The machine is designed to sit at the bottom of the ocean. It consists of a sheet of natural rubber and fiberglass composite that sits on top of a network of hydraulics and tubes. The “wave carpet” sheet mimics the underwater waves and is stimulated by the motion of the waves. This continuous motion is then translated to hydraulic power. The power is carried to the surface with the help of tubes and then it is converted to electricity with specially-designed generators.
Interestingly, the carpet was inspired by the mud at the bottom of the ocean. Researchers noticed that the ocean waves are less aggressive where mud absorbs the energy, so they decided to put the carpet at the bottom of the ocean to mimic the mud.
Ideally, the carpet will be installed at a depth of 60 feet with a flat ocean topography. Areas with little reefs are preferred so that there can be as little effect on marine life as possible.
The technology has a few advantages over contemporary sources of energy. Prof. Alam estimated that about 70 percent of the human population lives along the coastline. So, if the source of energy is right next door, as opposed to power plants in distant areas, it significantly reduces the cost to transport energy.
Furthermore, the energy density of waves is tenfold of any other source of energy. For a better understanding, Alam gave a comparison that “a football field full of solar panels provides the same power as a ten-meter wave carpet.” This means that a ten-meter of wave carpet is enough to provide power for 40 households.
Despite all the benefits that wave energy has to offer, there are a lot of obstacles that prevent this technology from going mainstream. The cost of implementation can be safely assumed to be the primary hurdle. Prof. Alam noted that “there are over a thousand patents and different wave energy devices that can at least turn on a little light bulb,” but he further stated that “the industry cares about the overall cost and whether or not it can compete with fossil fuels.”
The waves in the ocean are usually very big. These huge waves demand similarly gigantic devices to harness their energy. However, this large scale also drives up the cost to build these machines, making the research more expensive.
In addition to tackling the large waves, the need to make these devices robust also drives up the cost. Prof. Alam added that “we don’t want the device to get detached from the seafloor. It has to be designed for extreme conditions too, such as storms. So, the device becomes heavier.”
Moreover, wave energy devices need a large testing location. But obtaining permits for test sites is also difficult and can take up to 6 months or more. Not only it is time-consuming, the cost to rent a barge for transportation can be as expensive as $ 50,000 per day.
The complexity of designing these machines also poses additional problems. Prof. Alam said that “designing an aircraft is a piece of cake when compared to designing a wave energy device.” According to him, “the working conditions of an aircraft consists of wind coming from one direction. However, waves have multiple spectra with multiple frequencies from all different directions.”
Given all that is preventing this technology from hitting the mainstream market, Prof. Alam is still very hopeful. He mentioned that one of his graduate students, Marcus Lehmann has even started his own company which is based on the wave carpet technology. The company, CalWave Power Technologies Inc. is making progress to bring this technology to the market. CalWave has repeatedly won innovation awards at several renowned platforms. In June of 2017, Department of Energy 4 (DOE) awarded CalWave a multimillion-dollar award to support further testing and validation. Yet again, in November of 2019, DOE granted CalWave its support to design its second generation of a wave energy converter.
California has a target of using 100% renewable energy by 2045. With technologies like the wave carpet, it might actually be possible.
The work that engineers do shapes the world around us. But given the technical nature of that work, non-engineers may not always realize the impact and reach of engineering research. In E185: The Art of STEM Communication, students learn about and practice written and verbal communication skills that can bring the world of engineering to a broader audience. They spend the semester researching projects within the College of Engineering, interviewing professors and graduate students, and ultimately writing about and presenting that work for a general audience. This piece is one of the outcomes of the Fall 2019 E185 course.
