Tag Archives: energy

Green Infrastructure and Energy

In February the city of Austin was added to American Forests’ list of “Top 10 Best Cities for Urban Forests.”  The city beat out 40 of the most populous cities in the nation for its efforts in civic engagement, strategies in infrastructure, accessibility, health and condition, documented knowledge, and management of urban forests [1].  The award is good news for Austin considering the benefits of urban forestry as a part of green infrastructure (GI) which not only includes street trees, but also includes green roofs, green facades, permeable pavements, rain gardens, and stormwater treatment swales. 

GI is known for its ability to enhance storm-water management and water quality, improve human health by improving air quality and reducing UV exposure, reduce pavement maintenance costs via reduced deterioration, and increase property values.  Less well-known, however, is the potential green infrastructure has to reduce energy consumption.  

Urban trees, for example, have the potential to reduce energy use by providing shade, wind control, and active evaporation.  “Homeowners that properly place trees in their landscape can realize savings up to 58% on daytime air conditioning and as high as 65% for mobile homes,”[2]  Proper tree placement is important to achieve these savings so utilities have teamed up with urban foresters to promote programs such as “Plant the Right Tree in the Right Places.”  The following diagram provides recommendations from the Environmental Protection Agency for tree placement to maximize energy savings [3].


Green roofs, on the other hand, have the potential to reduce energy consumption by lowering surface temperatures.  A comparison between a green roof and a conventional roof in Chicago, for example, showed a temperature of 169 degrees F on a conventional roof and a range from 91-119 degrees F on the same day on a green roof of an adjacent building [3].


Unfortunately green infrastructure has gotten off to a slow start.  Traditional challenges have included underinvestment, a patchwork of uncoordinated efforts, the need for tailored solutions and the limits of sharing lessons learned, a lack of experience and dependency on public education, and the crossing of jurisdictional boundaries.  Despite these challenges many efforts across the United States are relying on both voluntary and policy initiatives in order to take advantage of GI benefits as part of an energy, air quality, water, and sustainability efforts [3]. 

[1] American Forests. “10 Best Cities for Urban Forests.” Web. February 2013. http://www.americanforests.org/our-programs/urbanforests/10-best-cities-for-urban-forests/

[2] Keep Indianapolis Beautiful, Inc. Benefits of Urban Trees. Web. 4 Apr. 2013.

[3] Reducing Urban Heat Islands: Compendium of Strategies. Environmental Protection Agency, 2013. Web. 18 Apr. 2013.


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So you’re telling me that my electric car’s battery is in the paint?

What comes to mind when you picture a battery? The familiar Duracell Coppertop AA battery? A clunky  automotive battery? The small rectangular battery in your cell phone? Researchers at Rice University are reinventing the concept of batteries and battery packaging by creating a lithium-ion battery with spray paint. That’s right, your local neighborhood hoodlum taggers can now be more energy forward than you sitting at home watching Cops.

A team of researchers from Rice University have demonstrated in a paper in Nature Scientific Reports that special “spray paints” can be used sequentially to build up the layers needed to form a lithium-ion battery. A spray-on battery could be used on a variety of materials, both rigid and flexible. They point out that the technology could be coupled to energy conversion devices such as solar cells.

Simply put, a lithium-ion battery is created by tightly layering cathodes and anodes like in the image shown below. The researchers at Rice University replicate this cylindrical design in a customizable form using the spray coatings that they developed. They applied the battery painting process to a variety of materials including stainless steel, glass, ceramic tile, and flexible polymer sheets. An SEM image of a cross section of the battery is shown below. Each of the spray painted batteries performed as a typical battery. They even applied the spray paint to a coffee mug to spell out the name of their Alma mater while also storing energy. They added that more complicated surface geometries could be possible using different spray nozzle designs that are tailored to the different viscous properties of the paints.

The are a few drawbacks to a spray painted lithium-ion battery. For one, the materials are highly toxic, corrosive, and flammable, hence why they are always tightly packaged and hidden away in their conventional form. Secondly, the batteries are highly sensitive to oxygen and moisture. This sensitivity currently restricts their widespread use because they still have to be packaged like their conventional brethren, reducing their novel promise. A spray painted battery is shown below on a glazed ceramic tile alongside its final packaged form. One of the researchers’ next steps is to develop a sealing layer to protect the batteries from these elements. Because who wants to paint their electric vehicle with a new battery but then have the painter tell them that they always have to keep the car cover on.

Typical lithium-ion battery construction.

Conventional and spray painted lithium-ion batteries.


SEM image of spray painted lithium-ion battery cross section.


Glazed ceramic tile with spray painted battery prior to packaging (left) and post-packaging (right)



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Salinity gradient power rising as a realistic renewable energy source

Estuaries are the locations where river water mixes with seawater. They are found along coastlines throughout the world, but what most people don’t realize is the significant potential to produce clean energy from these mixing water streams. The salinity gradient between the two streams of water contains a large amount of osmotic power, which can be thought of as the available energy (or chemical potential) from the differences in salt concentration between the fresh water and seawater. The enormous amounts of energy released where freshwater and seawater meet “can be utilized for the generation of power through osmosis”, which is “defined as the transport of water through a semi-permeable membrane.” [1]

The idea of obtaining energy from osmosis, or salinity gradient power, has been studied for decades, but in early 2009 two teams were racing to be the first to build a working prototype power plant making salinity gradient power a feasible method for renewable energy generation. Both teams have been working on the development and implementation of a membrane based osmotic process, but their approaches for generating the electricity are very different [2]. Westus (The Centre for Sustainable Water Technology), located in the Netherlands, is focusing on the Reverse Electrodialysis (RED) method to produce electricity. They claim that they will utilize fresh water from the Rhine river and saltwater from the North Sea to construct a type of battery by employing two membranes permeable to ions, but not to water. Utilizing the saltwater, one membrane will allow the passage of positively charged sodium ions into a stream of fresh water and the other membrane will allow the passage of negatively charged chloride ions into another channel of freshwater. The separated charged particles with electrodes placed in both streams makes up the chemical battery, which directly produces electricity. [2] Statkraft, a leading renewable energy group located in Norway, is focusing on Pressure Retarded Osmosis (PRO) as their method to extract electricity from salinity gradients. This method utilizes a membrane, permeable to water, to draw fresh water into the concentrated salt water, thus increasing the pressure in the salt water chamber. The resulting pressure can then be used to drive a turbine to produce electricity. In November of 2009, Statkraft opened the world’s first prototype osmotic power plant in Tofte Norway. [3] This facility had a limited production capacity (of around 4 kW) and is mainly used for testing and validation of data, hopefully leading to the construction of a large commercial power plant by 2015.

While the idea of harvesting free energy from estuaries and salinity gradients may seem like a flawless idea, it comes with both pros and cons. On one side, the technology is considered “as green as it gets”, with the only waste product being brackish water, which flows into the sea mixing with the sea water [2].  It is a constantly flowing source of renewable energy, unlike the intermittent energy provided by sources such as solar or wind power. It can also easily be combined with existing power plants and industries and can be built underground, thus reducing costs and visual pollution [2]. On the other side, the membrane technology still has a long way to go. The membranes are prone to bio-fouling from algae and silt, which reduce the membrane’s lifetime and efficiency. Salinity gradient power is mainly suitable only for places where there is an abundant supply of freshwater meeting saltwater, which clearly favors countries with a large coastline [2]. Also, the environmental impact and environmental policy should be considered for future plants of this type. First off, there are many species of aquatic life that are adapted to survive in waters with a specific range of salinity concentrations, and these power plants could affect the salinity of an area of water. It has been found that large salinity changes in aquatic environments can result in low densities of plants and animals [4]. Then one must consider the environmental policy and impact of structures that intake such large volumes of river water and sea water. These power plants must conform to strict construction permits and environmental regulations.

While many issues dealing with the viability of salinity gradient power as a renewable energy source are still being addressed, advancements in the technology are constantly being made. In June of 2012, Statkraft’s head of osmotic power said “We see that the development of technology is accelerating and that an industry is emerging. The membranes we are testing at Tofte this summer are ten times more efficient than the ones we installed during the opening of the prototype in the autumn of 2009” [5]. Earlier this year, researchers discovered a new more efficient way to harness osmotic power utilizing Boron nitride nano tubes [6]. They claim that a 1 meter-squared membrane using this technology could have the same 4 kW capacity as the whole Statkraft prototype power plant. This experimental device, which is three orders of magnitude more efficient than the current system, could significantly enhance the commercial viability of salinity gradient power as a realistic source of energy [6]. While the ultimate future of salinity gradient power is unknown, it has the potential to be one of the prominent renewable energy sources on the planet.

[1] http://www.statkraft.com/energy-sources/osmotic-power/

[2] http://www.gizmag.com/salinity-power-renewable-energy-osmosis/11206/

[3] http://www.gizmag.com/statkraft-osmotic-power/13451/

[4] Montague, C., Ley, J. A Possible Effect of Salinity Fluctuation on Abundance of Benthic Vegetation and Associated Fauna in Northeastern Florida Bay. Estuaries and Coasts. 1993. Springer New York. Vol. 15 No. 4. Pg. 703-717

[5] http://www.statkraft.com/presscentre/news/statkraft-considering-osmotic-power-pilot-facility-at%20sunndalsora.aspx

[6] http://www.gizmag.com/osmotic-salinity-gradient-power-nanotubes/26623/

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Straws of Life: A Global Solution

We take for granted the fact that we live in a country that provides easily attainable clean drinking water. Water fountains provide tap water that has been purified of disease-causing bacteria and are widely available and accessible to the public. Clean drinking water has evolved into an expectation for us; it is now considered a basic human right to have access to improved sources of drinking water.

Sadly, this is not the case for underdeveloped countries.

Worldwide, 783 million people drink water that is unclean and unsafe [2].

RTEmagicC_739px-Mwamongu_water_sourceThese unsanitary conditions, usually typical for third world countries, can be deadly. It is estimated that up to 4,000 children die every day from diarrheal disease and other illnesses caused by unclean drinking water [1][2]. Most of these countries don’t have the infrastructure to provide clean water, or any other form of residential energy, for the public. Africa is in real trouble: “Of the 25 nations in the world with the greatest percentage of people lacking access to safe drinking water, 19 are in Africa” [3].

The main cause for lack of clean water is simple lack of power. Impoverished countries don’t have the energy (or money) to construct and operate water treatment facilities. Having said that, necessity is the mother of invention; in 2005, the swiss-based company Vestergaard Frandsen found a solution: It’s called LifeStraw. [4]


The LifeStraw is a handheld straw-like device that allows the user to filter water as they drink it.lifestraw-a-diagram

When a user sucks on the top of the straw, water is pulled through hollow fibers with pores 0.2 microns in length. These small pores trap any bacteria, parasites, or impurities in the water as it flows up to the user’s mouth [6]. It’s a relatively simple strategy, and is fairly effective. It removes 99.9% of bacteria and parasites from the water. One of these straws can last for 1,000 liters; this is equivalent to sustain one grown human with drinking water for a year [5].

While this device seems like a life saver, it has some limitations. Firstly, it is unable to filter out chemicals and water-borne viruses. However, the main issue is with the cost of the item. While only $6.50 per personal LifeStraw, citizens of impoverished nations still can’t afford them [1].

Again, Vestergaard came up with a solution to that problem: they donated LifeStraws to over 4.5 million Kenyans.  LifeStraws help users to bypass burning wood to boil water, which helps Vestergaard earn carbon credits. The company can then sell these credits to other companies who need to offset their carbon emissions [1]. In this way, Vestergaard can save lives while the pollutant companies pay for it.

Some people are upset with Vestergaard’s philanthropic move on the basis that the public image covers up the profit that they are actually making [1]. But I’m pretty sure the Kenyans aren’t complaining, and no one can argue against the value of lives saved.



[1] Barksdale, Martha, and Kate Kershner. “How LifeStraw Works.” HowStuffWorks. N.p., n.d. Web. 02 Apr. 2013.

[2] “Clean Water Campaign.” Clean Drinking Water. N.p., n.d. Web. 02 Apr. 2013.

[3] David, Michael,, David,, and Caroline. “Africa.” ThinkQuest. Oracle Foundation, n.d. Web. 02 Apr. 2013.

[4] “LifeStraw FAQ.” Waterforlifestraw.co.uk. N.p., n.d. Web. 02 Apr. 2013.

[5] “LifeStraw Frequently Asked Questions.” LifeStraw Frequently Asked Questions. N.p., n.d. Web. 02 Apr. 2013.

[6] “LifeStraw.” Wikipedia. Wikimedia Foundation, 04 Feb. 2013. Web. 02 Apr. 2013.

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Solar Aviation: Around the World in 80 Days by 2015

A recent article from Forbes introduced me to a new technology I honestly would not have expected to exist: manned airplanes powered by solar energy. [1] Solar Impulse – the name of the Swiss company and the actual plane– offers an addition to a field that has been steadily developing since the 1970s. [2] The plane contains approximately 12,000 solar cells and four lithium-polymer batteries. These solar cells cover the 208 foot wingspan and give the craft an feather-like appearance. [1] After reading the headline and looking at the photo below, I found myself thinking of Icarus, the overconfident boy in Greek mythos who flew too close the sun. (A nerdy confession I know, but hopefully my ninth grade English teacher would be proud.) The story is one of hubris and failed ambition, and I could not help but think it applicable here. Interesting and innovative though they may be, are such advances in solar aviation really helping us combat the energy crisis?

The first solar-powered flight took place in California on November 4, 1974. “Sunrise I” was a tiny unmanned craft that weighed practically nothing and flew for approximately 20 minutes. A few years later, the first piloted solar aircraft (“Solar One”) used nickel-cadmium batteries with some success. [2] Progress in the field developed through the decades, with crafts such as the “Gossamer Penguin”—first to fly purely on solar energy, the “Sunseeker”—now the only solar aircraft in continuous operation, “Helios”—which reached nearly 30,000 feet in 2001, and Alan Cocconi’s craft—first to fly through an entire night, all contributing their fair share in honing solar aviation technology. [2] [3] But the Solar Impulse project is seeking to make the achievements in solar aviation less of a novelty and more of a practical solution to energy concerns. The company has aspirations to be the first to circumnavigate the globe with a larger aircraft in 2015. [4] The current “Solar Impulse” uses electricity produced from solar cells that can generate up to 45 kW of power. There are four, 10-horsepower electric engines on board that allow the plane to average about 40 miles per hour. [1]

That’s not very fast. In fact, numerous precautions are taken into account in order to avoid inflight complications, such as limiting weight (“Solar Impulse” is 3,500 pounds) and taking off early in the morning then landing at night. [1] An engineer and pilot associated with the project stated that the commercial applicability of solar aircrafts was still four decades away. And yet, the Solar Impulse project has demonstrated that solar energy can be a “stand-alone fuel”. [4] These early stages in developing a technology are admittedly slow. At this moment, solar aviation may not be immediately applicable to our energy problems. But commercial airlines are burning through fossil fuels and the innovation spurred by companies like Solar Impulse may someday be a saving grace for transportation. This is a long-term investment that may prove to be more of a gamble, but I’d rather take that risk now even if at the end of the day we get a little too close to the sun, our wax melts, and the whole project crashes and burns…metaphorically, of course.


[1] http://www.forbes.com/sites/uciliawang/2013/03/28/get-ready-for-a-solar-power-planes-maiden-flight-across-the-u-s/?ss=business%3Aenergy

[2] http://ecoble.com/2009/02/16/sun-power-jet-fuel-for-the-21st-century/

[3] http://www.solarimpulse.com/en/airplane/solar-aviation/

[4] http://gigaom.com/2013/01/30/coming-to-america-a-swiss-solar-powered-plane/

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Ethanol and the Quest for Energy Independence

Recently, the United States has pushed for new energy sources to fuel our transportation sector and the overall economy. Ever since the oil crisis of the 1970s, the country’s dependence on foreign petroleum has been evident. Since then, a growing portion of our energy sector has come from corn ethanol. This growth has mostly been due to policies the US government has implemented over the past 10 years in order to achieve energy independence in a way that is sustainable and environmentally friendly. While the US has only recently started implementing these policies, Brazil has already achieved energy independence through their use of sugar cane ethanol.


With the passage of the Energy Policy Act in 2005, all gasoline retailers were mandated to blend 7.5 billion gallons of ethanol made from corn annually by 2012. This was called the Renewable Fuel Standard. Its main purpose was to reduce greenhouse gas emissions, decrease reliance on foreign oil supplies, and create jobs (mostly in the agricultural sector). Two years later, the Energy Independence and Security Act of 2007 was passed which ratcheted up the ethanol mandate to blending 13.2 billion gallons of corn-based ethanol by 2012 and rising to 36 billion gallons by the year 2022.


Congress sensed the challenge this mandate would pose and proposed the Domestic Alternative Fuels Act in January 2012 which had bipartisan support. This act would allow sources other than corn to be used in ethanol production. This bill received a huge amount of backlash from corn farmers, agribusiness and its stakeholders because the legislation would loosen their foothold in the biofuel industry.

Brazil has come a long way on its journey to energy independence, however it can be seen as somewhat of an anomaly. The US has had some success in using ethanol and biofuels but hasn’t achieved the level of independence Brazil has. This can be attributed to more favorable conditions in Brazil such as vast amounts of fertile land, government policies, and heavy investment in infrastructure.

Agence France-Presse - Getty Images

The main push for Brazil’s energy independence came back in the 1970s when oil prices increased at an unprecedented rate and countries realized how susceptible they were to the swings in the global oil market. Following the crisis, the Brazilian government looked towards other solutions to help the country be less susceptible to the unpredictability of the global oil market. The answer came in the form of a crop that they had already been producing and exporting for decades: sugarcane. In 1975, ProAlcool (Programa Nacional do Álcool) was created by presidential decree. The purpose of this program was to utilize Brazil’s robust sugarcane industry to produce ethanol for the purpose of fueling automobiles.

The first part of this strategy was a mandate that by the year 1980, 3.5 billion liters of ethanol be produced annually. Along with this mandate came a large amount of subsidies to aid farmers in adding ethanol distilleries. This strategy would increase the ethanol supply so it would be widely available across the country. The second piece of their strategy was to forge an agreement with automakers in 1979 to start producing more cars that ran on ethanol. The government in turn launched a robust media campaign to inform the public on the benefits of these new flex-fuel cars.

While the US set some policies in reaction to the global oil crisis, the problem seemed to fade once oil prices stabilized and the American public turned their attention elsewhere. Brazil on the other hand maintained its resolve and implemented policies long after oil prices dropped. From what critics saw as just a short-term boost to Brazil’s sugarcane industry, emerged a comprehensive plan to reach the country’s energy independence goal.

Many parallels can be drawn between the US and Brazil on their quests to achieve energy independence. Even though these two countries are different on many economic, social, and geographical levels, we might be able to gain some insight from their policies and implementation methods in order to reach our goal here in the US.


  1. http://www.economist.com/node/21542431
  2. http://www.nytimes.com/2004/12/18/business/worldbusiness/18iht-menergy_ed3_.html?_r=0
  3. http://www.afdc.energy.gov/fuels/ethanol_fuel_basics.html
  4. http://www.theecologist.org/News/news_analysis/1077685/our_sugarcane_is_greener_than_your_corn_brazil_takes_on_us_biofuel_industry.html
  5. http://www.ibtimes.com/how-brazil-turned-ethanol-unique-success-1064308


  1. http://www.planetforward.ca
  2. http://www.usda.gov
  3. Agence France-Presse – Getty Images

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The Evolution of Geothermal

You can only operate a geothermal power plant in the presence of abundant geothermal energy, right? Wrong! Well, sort of.

Source: Personal Collection

Geysir, Iceland
Source: Personal Collection

Historically, the building and operation of geothermal power plants has been tightly restricted to geothermally active areas. Think places like New Zealand, Iceland and the Philippines, where energy literally comes bubbling out of the ground in the form of hot springs, geysers and steam. These areas are usually found on the boundaries of the huge tectonic plates that make up the earth’s lithosphere. Along the borders of these plates, geothermally heated aquifers often flow relatively close to the surface, and these sources of energy are simply begging to be harnessed. The problem is, however, that the areas where these conditions exist make up less than 10 percent of Earth’s dry land.

What About the Cool 90 Percent?

Here is the good news. Geothermal energy originates below the earth’s crust, where the steady decay of naturally radioactive materials produces heat continually. Theoretically, this source of energy is available virtually everywhere, albeit at a greater depth than in the previously mentioned, geothermal areas. The total amount of thermal energy within a depth of 10 km from the earth’s surface is estimated to be 50,000 times greater than all the natural gas and oil resources in the world.

Efforts to harness this hidden energy are already being made in various places across the globe, using a new technology called Enhanced Geothermal Systems (EGS). The method essentially expands traditional geothermal energy production through the use of hydraulic fracturing. It consists of drilling a well to a depth of about 3 to 10 km, where temperature levels are usually between 70 and 315°C. In contrast to EGS, traditional geothermal power plants usually only require wells that are 2 to 3 km deep, in order to reach the same temperature levels. Upon reaching this depth, water is pumped into the dry layers of hot rock at high pressure, which causes the rocks to break and thus increases their permeability. Cold water is then pumped down through an injection well, where it flows through the hot rocks before returning back to the surface as steam, through a separate well. The steam is then run through a turbine where it produces electricity, before it is cooled and condensed, and pumped back into the ground.

Source: EERE

The EGS Process
Source: EERE

An Earth-Shaking Prospect

This technology offers a number of different benefits. First of all, it introduces a vast supply of geothermal energy potential to areas that have hitherto been considered too cold for such ventures. The EGS technology also enjoys many of the same benefits associated with traditional geothermal energy production. It is a steady, renewable source of energy and geothermal plants require very little land space per MW produced, in comparison to other types of power plants. However, drilling in itself is a messy and expensive business, and as the technology is still in its infancy, the upfront cost of an EGS project remains very high.

The technology also has to deal with the issue of induced seismicity, as the injected water can act as lubricant on highly stressed layers of rock near geological fault lines. In 2009, a $60 million EGS venture was cancelled in Basel, Switzerland, due to a flurry of earthquakes that were generated as a result of the project. While the momentum of EGS has been lessened by setbacks such as the Basel shutdown, as well as the under-delivery of other ongoing projects, the potential benefits that the technology promises are hard to negate. Proponents of EGS are still willing to brace the significant learning curve that lies ahead, before the technique becomes both technologically refined and cost competitive, and geothermal becomes a global source of renewable energy.


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