Evaporation as a renewable energy source

Researchers at Columbia University, led by biophysicist Ozgur Sahin, have developed an “evaporation engine” that uses bacterial spores that expand in the presence of humidity and contract when the humidity is low.

While this technology was first described in a 2015 paper in Nature, the group recently made headlines again when they wrote a paper describing the potential for natural evaporation from U.S. lakes and reservoirs to generate 325 gigawatts of power!  That represents nearly 70 percent of the electricity currently generated by the United States. Their analysis, published in Nature in Sept 2017, revealed that the energy potential available from evaporation is comparable to that of wind and solar power but unlike wind and solar is characterized as low-intermittency. According to the authors, these findings “motivate the improvement of materials and devices that convert energy from evaporation.

This is the just kind of innovation that I believe needs to make its way into classrooms to inspire the next generation of scientists and engineers.  This new technology also provides an opportunity to invite your students to evaluate the challenges that will need to be studied in order to use this technology on large bodies of water. For example, the authors cite that “using evaporation driven materials and devices on lakes or reservoirs could affect freshwater resources” but that this technology could reduce evaporative losses in regions characterized by water stress and scarcity.  The authors conclude that “these materials and devices could potentially contribute toward solving energy and water related challenges.”

Below I have listed some classroom-ready resources should you want to introduce this technology to your students:

Renewable Energy from Evaporating Water (5 minute video with Ozgur Sahin)

Evaporation-powered devices in action (4 minute video)

A miniature car driven by evaporation (Under 1 minute video)

ScienceTake | The Spore Machine (1:36 minute video from the New York Times)

Engineering Evaporation (6 minute conversation between Ozgur Sahin and Ira Flatow on NPR’s Science Friday)

Evaporation could power most of the U.S. — study
Greenwire, September 26, 2017

Water evaporation could be a promising source of renewable energy
The Verge, September 26, 2017


Guest Post: Evolving Electric Industry Represents New Career Opportunities by Jordan Kern, PhD

Eliminating greenhouse gas emissions in the electric power industry might require it to change from top to bottom – the technologies that are used, the business models employed, the number and scope of market participants, and the regulatory oversight required. The only thing that we can safely say won’t change are the laws of physics that impose constraints on the operation of power systems.

The good news (at least for folks who are concerned about climate change) is that the electric power industry is changing quickly, largely due to technological advances and policy pressure. What that means for conventional, vertically integrated electric power utilities – companies like Duke Energy— is a little uncertain, but they’re spending a lot of time thinking about how they can be successful players in the grid of the future.

As the electric power industry evolves, another thing we’re learning is that there is a big need for an influx of new workers with a broader set of expertise. Some of this need is related to the facts of life: baby boomers who worked their whole careers at power companies are retiring. Some industry estimates project that 50% of the workforce at electric power utilities will retire over the next several years, and these folks will need to be replaced.

Image from Utility Dive

But perhaps more importantly, the types of skills needed in the electric power industry are changing in a number of ways:

  • For one, the future of the industry may not be dominated by conventional electric utilities or for that matter, even by suppliers of energy.
  • In a grid dominated by renewables, demand side management (i.e., managing and reacting to customers’ behavior) and storage will become critical components.
  • Even at big utilities, the pathway to a job is no longer limited to mechanical and electrical engineering. Increasingly, utilities need workers with skills in data science, software development, business, and marketing.

In a lot of ways, this shift benefits UNC students. Even though the technical rigor necessary for a career in the energy industry has been available at UNC for a long time, without a significant undergraduate engineering presence on campus, some doors have been closed to our graduates.

The shifting nature of energy industry means new doors are springing open. We just need to make sure UNC grads are walking through them.

Part of that means exposing students to the benefits of marrying their intellectual and philosophical interest in sustainability to tangible career pathways. For more on the incredible strides UNC has taken in this regard, you should read UNC professor Greg Gangi’s recent blog post.

Another important aspect of preparing students for new opportunities in the energy industry is adapting undergraduate curriculums. At UNC, the Curriculum for the Environment and Ecology (ENEC) is doing just that, having recently hired a new lecturer in Energy.

I’ve tried to do my own small part too, by developing an Energy Modeling and Analytics course (ENEC 490), which is offered in the fall. The course uses a “flipped classroom” approach, with formal lectures delivered online via YouTube, and in-class time used to develop coding and modeling skills through the completion of industry case studies.

One of the things I’ve been most impressed with over the last several years is how these shifts in focus at UNC and within ENEC have been spurred by student interest.

On the part of the university and ENEC, this shows not only a willingness to adapt quickly (not always a strength of big institutions), but also a recognition that, in terms of defining societal priorities and creating new areas of economic and intellectual growth in the future, the students are often the teachers.

Jordan Kern is a Research Assistant Professor at the UNC Institute for the Environment. You can learn more about his research and teaching portfolio at http://jdkern.web.unc.edu/

Guest Post: How much energy is in your water bottle? by Ryan Kingsbury

We don’t often think about the energy it takes to satisfy our thirst, but where we get our drinking water has huge consequences for how much energy is needed. In many parts of the world, fresh water sources like lakes or aquifers are becoming scarce, forcing residents to settle for supplies that aren’t as clean. And the dirtier the water, the more energy it takes to purify.

Salt is especially hard to remove. In desert or coastal regions with limited sources of freshwater, residents must use a process called desalination to turn salty groundwater or seawater into drinking water. We’ve already covered how mixing saltwater with freshwater releases a lot of energy,  so, to do the reverse– to remove salt from water– consumes a lot of energy.

Exactly how much energy is required depends on the method of desalination. Distillation (which involves boiling)  is a simple way to desalinate water, but it’s also one of the most energy-intensive. By using a technology called reverse osmosis, we can desalinate water using about 1/10th as much energy as distillation. So compared to boiling the water, using reverse osmosis is much more efficient. But reverse osmosis still requires about 100x more energy than treating fresh surface water or groundwater. In fact, you could charge your smartphone with the energy it takes to desalinate just 1 gallon of seawater!

Despite its energy demands, desalination is widely used around the world. There are more than 18,000 desalination plants in 150 countries, including about 250 in the U.S. About half of these plants use reverse osmosis, and about a third use distillation.

In the U.S., most plants are located in Florida, Texas, and California (shown on this cool map), but there are about a dozen here in North Carolina. If you’ve ever visited the Outer Banks, your drinking water probably came from a reverse osmosis desalination plant.

There are so many reverse osmosis plants in the world, that together they produce 4x as much water in one year as refineries do oil! But virtually all of these plants were built as a “last resort,” in areas where there simply isn’t enough freshwater to meet the needs of consumers, industry, and agriculture. When it’s available, treating freshwater is always preferable to desalination.

The more we have to rely on seawater and other salty water resources, the more energy it will take to slake our thirst. So next time you take a drink of water, remember that you’re not just drinking ounces, you’re drinking watts.

Want to learn more about reverse osmosis desalination? Check out this animated video from the Seven Seas Water Corporation.

Ryan Kingsbury, P.E., is a PhD student at the University of North Carolina at Chapel Hill where he is a member of the Coronell Research Group.  Orlando Coronell, PhD, and his research team study membrane-based processes for water purification and energy production and storage, with applications in municipal, industrial, and household systems. Ryan studies salinity gradient energy which you can read more about here.

New NOVA Program: The Nuclear Option

Tonight (January 11, 2017) at 9PM on PBS, a New NOVA Special titled The Nuclear Option will air. A related PBS Newshour segment, Innovating the next generation of nuclear power, is available for online viewing and may also be of interest.

Program Summary (NOVA): Five years after the earthquake and tsunami that triggered the unprecedented trio of meltdowns at the Fukushima Daiichi nuclear power plant, scientists and engineers are struggling to control an ongoing crisis. What’s next for Fukushima? What’s next for Japan? And what’s next for a world that seems determined to jettison one of our most important carbon-free sources of energy? Despite the catastrophe—and the ongoing risks associated with nuclear—a new generation of nuclear power seems poised to emerge the ashes of Fukushima. NOVA investigates how the realities of climate change, the inherent limitations of renewable energy sources, and the optimism and enthusiasm of a new generation of nuclear engineers is looking for ways to reinvent nuclear technology, all while the most recent disaster is still being managed. What are the lessons learned from Fukushima? And with all of nuclear’s inherent dangers, how might it be possible to build a safe nuclear future?

What do pickles have to do with generating electricity?

Earlier this year I heard University of North Carolina (UNC) at Chapel Hill doctoral student Ryan Kingsbury, a member of Orlando Coronell’s lab discuss his research and was introduced to the term “blue energy” for the first time.  Ryan studies energy storage and generation from salinity gradients.  Salinity gradient energy or “blue energy” refers to the energy released when water with different concentrations of salt mix (this is essentially the reverse of what happens during desalination).  For those of you who teach about diffusion, here is an opportunity to show your students how selective diffusion of positive and negative ions across membranes can drive the production of  electricity!

Salinity gradient energy is at the cutting edge of research on renewable energy.  Using ion-selective membranes and a process known as reverse electrodialysis (RED), natural and industrial waters (e.g. seawater, desalination brine, etc.) can be used to store energy, generate electricity and even treat wastewater!  Ryan recently described the physics behind blue energy and RED in a bit more detail in his own blog post.

And now for the pickle part.  It turns out one of the industrial wastewaters being investigated by researchers is the leftover salt water from making Mt. Olive pickles!  Researchers from NC State University, UNC-CH, East Carolina University and the Coastal Studies Institute are developing a process that uses salinity gradient to release energy from Mt. Olive wastewater. There is a 6 minute video describing this multi-institutional collaboration and a transcript of the video also available. The project PIs (Dr. Coronell from UNC and Dr. Call from NCSU) also participated in a February 2016 radio interview about salinity gradient energy which explains their project more broadly.

In addition to pickles, NC is also known for its estuaries; the mixing of salt and fresh water that occurs in estuaries is an untapped source of blue energy!  In fact, I learned from reading Ryan’s blog post that where rivers flow into the sea and fresh and salt water mix, the amount of energy created  is equivalent to the river falling into the ocean from the height of the Eiffel tower!

You can also learn more about blue energy in this June 2015 BBC article Blue energy: How mixing water can create electricity.





2017 BioenergizeME Infographic Challenge from the U.S. Department of Energy

The 2017 BioenergizeME Infographic Challenge kicks off today!  This year’s theme is  Exploring the Future American Energy Landscape.  The US Department of Energy’s Bioenergies Technologies Office is  asking 9th- through 12th-grade student teams to use technology to research, interpret, apply, and then design an infographic that responds to one of five research topic areas selected for 2017:

History of Modern Bioenergy

Bioenergy and Society
Workforce and Education

Science and Technology

Even better, all of the tools necessary to integrate this challenge into your curriculum or offer it as an after-school activity are provided!

BioenergizeME Toolkit

Five steps to building an infographic

Social media guide

BioenergizeME Research Strategy Guide

BioenergizeME Resource Library

To date no past submissions have come from NC – let’s change this!

To be considered for the competition, teams must register by Feb. 3, 2017 and infographics must be submitted by March 3, 2017.

Check out the 2016 award winning infographics on cellulosic ethanol, algae as a biofuel and energy from biomass You can view all previous winning infographics here. One NC teacher remarked that she would incorporate these  infographics into her AP Environmental Science class by having her students review and critique the infographics to decide which they would fund for further development.

Pipeline shutdown & gasoline supply in the Southeast

I live in the Triangle and have seen firsthand the effects of the partial shutdown of the Columbia pipeline as I have driven by many gas stations this week where no fuel was available.  An event such as this can be used to remind students where our gasoline comes from and to prompt them to consider the consequences of having to transport fuels over long distances.

The U.S. Energy Information Administration (EIA) featured the pipeline disruption and provided the map below in its September 21st, Today in Energy feature article (which you can sign up to receive each weekday via email).  According to this article “the U.S. Southeast is supplied primarily by pipeline flows from refineries along the U.S. Gulf Coast and supplemented by marine shipments from the U.S. Gulf Coast and imports.” Seeing this map helped me to understand why this pipeline disruption impacted central North Carolina to a great extent.

Source: U.S. Energy Information Administration

There is an online mapping tool available that enable users to create their own maps as they evaluate different energy sources.  I used the EIAs U.S. Energy Mapping System to quickly create a similar map that shows petroleum refineries (boxes); petroleum pipelines (dashed lines); and petroleum ports (ships):ppile

Then I added additional map layers to also show oil wells (light brown dots) and oil/gas platforms (dark brown dots) in federal waters so students can also see the distribution of wells and platforms in relation to petroleum refineries.


I would love to hear from teachers who have incorporated this current event into their instruction.

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