Archive for the 'Electricity' Category

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.





Accessing local, regional and national data on electricity supply and demand

I am an advocate for having students engage with real data and when that data is locally relevant, even better!  Access to real data about the electrical grid is what I like about the newly released U.S. Electric System Operating Data tool from the U.S. Energy Information Administration. This tool provides “analysis and visualizations of hourly, daily, and weekly electricity supply and demand on a national and regional level for all of the 66 electric system balancing authorities that make up the U.S. electric grid.”

There are three Duke Energy balancing authorities (BAs) in NC – Duke Energy Carolinas (DUK), Duke Energy Progress West (CPLW) and Duke Energy Progress East (CPLW).  From the tool’s interactive Status Map, you can view demand (actual & forecasted) and supply data for the BA that is servicing your school.  Hourly, daily, weekly and monthly demand data is available and can even be downloaded in excel should you want your students to conduct a graphing activity.

Map showing balancing authorities in North Carolina

Status map showing NC’s three Duke Energy BAs in blue, with data for Duke Energy Carolinas (DUK) shown (Sept 7, 2016). The size of the circle roughly corresponds to the system size.  By clicking on the corresponding blue dot you will find hourly, daily, weekly and monthly demand curves with these data available for download into excel for a graphing activity.

There is also a live feed that runs across the top of the tool that shows how many total megawatthours the US (the lower 48 states) consumed yesterday (approximately 9.77 million MWh on September 6th, 2016) as well as the latest US hourly demand and yesterday’s peak demand values.

From the Grid Overview home page students can also examine national or regional demand curves, like the weekly demand curve shown here for the Carolinas (CAR) region.

Weekly demand curve for the Carolinas (CAR) region.

What can students learn by examining a  daily or weekly demand curve?  In addition to seeing how many megawatt hours of electricity the Carolinas (CAR) region or a specific BA requires in any given day or week, students may also be able to examine and explain trends in electrical consumption over time and even seasonally.  For example, students could be tasked with examining the extent to which electrical consumption is tied to the weather and recent weather events. For example, the recent hurricane that passed through this region on Sept 3rd brought cooler weather and perhaps some power outages that reduced demand for electricity compared to the days before the hurricane.

This tool also enable users to assess the demand-supply balance for a given region (see below) or balancing authority such as Duke Energy Carolinas.  What can students learn by examining a visualization of demand and supply?  They will observe that  demand and supply closely match (they need to!) and that energy transfers (interchanges) occur to address any differences between demand and supply. The EIA’s About the Grid page in addition to the glossary may also be useful as you familiarize yourself with this tool and the terminology encountered.


Comparing demand and supply for the Carolinas region.





Don’t forget the infrastructure!

Earlier this month I conducted a teacher workshop devoted to the topic of electricity for science teachers from North Carolina’s coastal region. During the workshop I asked the teachers to tell me about the kinds of local energy issues they are confronting with their students and what questions arise in the classroom as a result.  One teacher remarked that in light of the Desert Wind Power Project being constructed in the northeastern part of the state, he asks his students to consider the infrastructure needed to build a wind farm.  His comment was timely, given that roads are currently being built to enable construction of the wind farm. When we evaluate the different energy sources that can be used to generate electricity we want our students to consider the accompanying infrastructure and land use change that results from the acquisition, management and use of those energy sources.eagleford_vir_2016046

NASA’s recent Image of the Day titled Shale Revolution featured the infrastructure and land use change brought about by oil and gas acquisition in the Eagle Ford Shale Play in Texas. The speckles of light in the nighttime satellite image below are “the electric glow of drilling equipment, worker camps, and other gas and oil infrastructure combine with flickering gas flares.” Comparing daylight satellite imagery from the years 2000 and 2015 revealed a “bustling network of roads and rectangular drill pads had completely transformed the landscape.”  Furthermore, this visual transformation invites the viewer to also consider the societal impacts of such development as well; Cotulla, Texas saw its population more than double in a very short time period!  Thus, these images could be used to prompt a class discussion about the implications of oil and gas development, including the accompanying infrastructure and land use changes, on the local community.

It will be interesting to compare satellite images of the land that will house the Desert Wind Power Project before and after the project is complete and to use these images to prompt student thinking about the environmental, economic and societal impacts of a land-based wind farm in rural North Carolina.

Interactive infographics from the IEA | World’s energy system through 2050

IEA World Energy 2012

The World’s Energy System in 2012

The International Energy Association’s publication Energy Technology Perspectives 2015, is accompanied by a set of interactive visualizations that utilizes the data and figures behind its publication on energy technologies.  I am an advocate for having students visualize the entire energy system – the diversity of energy sources used to provide electricity to homes and industry and to power our various modes of transportation.  I also find it useful to examine how the system is changing over time as our demand for energy grows in light of the need to limit society’s carbon dioxide emissions. These interactive infographics from the IEA illustrate how the world’s energy system will evolve through 2050.  There are three parts to this online tool: an energy flow visualization, an emissions reduction visualization and a transportation visualization. Here I am featuring the energy flow visualization where the  user can hover over a specific energy source, transformation or end user to study a particular energy flow.  The diagram below shows the global energy flow for coal in 2012 and for 2050 (projected); one can easily compare the two graphics to see that coal use will decrease while global energy demand will increase.  Have you considered asking your students to evaluate and explain energy flow diagrams?

IEA World Energy 2012 and 2050_coal

Global energy flow for coal in 2012 and for 2050 (projected).

The emissions reduction visualization tool allows the user to assess how individual countries or regions can reduce carbon dioxide emissions via deployment of technologies and energy efficiency measures under three different warming scenarios (2°C, 4°C and 6°C). The transport visualization tool enables the user to select an “indicator” such as annual road energy consumption for a specific country, region or the world to visualize the extent to which the selected indicator needs to change to limit Earth’s average global temperature to either 2°C, 4°C or 6°C.  According to the IEA website. “the 2°C Scenario is the main focus of ETP 2015. It lays out the pathway to deploy an energy system and emissions trajectory consistent with what recent climate science research indicates would give at least a 50% chance of limiting average global temperature increase to 2°C.”  You can read the Executive Summary of the ETP 2015 here.

And if you want to read more about energy flow diagrams, check out this post.

Duke Energy 2050 Vision | Online Challenge

I recently learned about this interactive online “Energy Challenge” by Duke Energy where users create a plan to meet the energy demand of  a carbon constrained world in the year 2050. Duke Energy aggregated data from across its entire U.S. service territory and created a visual representation of its service area and power generating facilities which sets the stage for the user who is tasked with making choices about how to meet a growing energy demand while working towards CO2 reduction goals.  Choices that can be made by the user include: building new power plants, including solar and wind farms, upgrading existing power plants to produce more energy, retrofitting existing plants to reduce emissions, closing inefficient power plants and implementing energy efficiency programs.


As users make decisions, such as retiring a set of aging coal plants or adding a wind farm, they get instant feedback regarding cost (in billions of dollars), impact on CO2 emissions (tons per year) and the extent to which their plan meets the predicted energy demand for the year 2050.  The energy demand meter displayed on the right side of the screen makes it easy to visually monitor the extent to which a decision helps to meet energy demand and the extent to which this demand is met through non-renewable energy sources, renewable energy sources and energy efficiency measures.

Duke Energy intends for this tool to “demonstrate the trade-offs and cost implications of choosing an energy generation mix that will meet future energy demand while minimizing CO2 emissions and keeping costs as low as possible.” I could easily see small groups of students competing to see which group can come up with a strategy that reduces CO2 emissions, meets projected energy demand for 2050 and costs the least amount of money.

To learn more about the game, click here.

One Indiana science teacher created a worksheet to accompany this game that could be used with your students.

If you have your students play this game, please share your experience by leaving a comment!



Exploring 2015 electricity generation data for the United States

Earlier this summer the Washington Post published an online map (using data from the Energy Information Administration) to help users visualize the current state of electricity generation in the United States. In addition to showing electricity generation by energy source from January to May 2015, the location and capacity (in megawatts) of each power plant is also featured. Additional maps show the distribution of power plants utilizing a particular energy source (e.g., coal plants operating from January to May 2015).

I think lots of discussions could arise by studying maps such as these with students.  Prompt students to consider how the sources of electricity that are used by a state or region are influenced by access to those energy sources.  What do students notice about the distribution of coal plants? Natural gas plants?  How might the observed trends relate to energy pricing, policies, etc.? One intention of the graphics is to show users that “Local electric utilities take advantage of the power sources most accessible to them: coal mines, dammed rivers, new supplies of natural gas or nuclear plants to generate the bulk of the nation’s electricity.”

Another interactive tool available let’s the user examine and compare how each state uses a particular energy source.  For instance, with a single click the user can view the states that generate the most electricity from wind.


International Energy Portal (EIA Beta version)

Earlier this week, the U.S. Energy Information Administration (EIA)  released the Beta version of its redesigned International Energy Portal, an interactive online tool that enables users to visualize global and country-specific energy data and trends through heat maps, bubble maps, column charts, and time series plots, some of which can be animated.  These data depict international energy use  for petroleum, coal, natural gas and electricity for over 200 countries for over 30 years, starting in 1980.


The screen shot above depicts primary coal production for the year 2012 and the data visualization tool enables you to examine coal production all the way back to 1980 – users can also download the data for further analysis and comparison. Image source:

You can learn more about the new features of this tool here. Features that will likely be of interest to teachers include the ability to:

  • “view and download complete data sets for consumption, production, trade, reserves, and carbon dioxide emissions for different fuels and energy sources.”
  • “compare compare data across different energy sources by converting to British thermal units, terajoules, and tons of oil equivalent.”
  • “choose specific countries, regions, and data series for review and comparison.”
  • examine “how energy production, consumption, reserves, imports, and exports have changed over time.”

If you enjoy using graphics in your instruction and like keeping up with energy news and trends, you may want to consider subscribing to EIA’s Today in Energy newsletter which brings a short article with accompanying graphics to your inbox each weekday.  It is a quick and easy way to stay up to date on “energy facts, issues, and trends.”

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