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)

 

Salinity gradient power rising as a realistic renewable energy source

Amazon River estuary
http://images.gizmag.com/gallery_lrg/11206_12030952855.jpg

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.

Statkraft osmotic power prototype
http://images.gizmag.com/gallery_lrg/osmotic-2.jpg

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/

The Evolution of Geothermal

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

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.

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.

 

Bunny Power!

What is a convenient way to get rid of an overpopulation of rabbits and stay warm at the same time?  Well, Sweden has found the answer!  Starting in 2006, the country began controlling its multiplying rabbit population and using the resulting carcasses to fuel thermal power plants.  While some may view this idea as gruesome and inhumane, others praise the plan as an inventive way of solving two problems at once.

To this day, Sweden has used well over 6,000 rabbits annually to fuel its heating centers [1].  The country contends that 100,000 tons of raw materials can create enough heat for 11,000 homes annually [2].  That’s a lot of bunny power!  The aim of the project is not only to control growing rabbit populations, which started by the release of a few household pets into a park, but also to prevent any threats of contamination posed by the massive amount of excrement to nearby residents.  As a plus, the program also reduces landfill waste that would have resulted from population control measures [2]!

 

 

But Sweden has gotten more heat from its bunny power than expected.  People for Ethical Treatment of Animals (PETA) responded to Sweden’s actions in outrage, claiming gross mistreatment of the rabbits [2].  Others question the overall productivity of the bunny burning, taking into account the energy used for bullets, gunpowder, freezing preparation, and transportation before the fuel even makes it to the boiler. 

But Sweden appears happy with the ‘success’ of the program and intends to continue; the country has even expanded its animal biofuel plant fuel mix to include dead cats, cows, deer, horses, and slaughterhouse waste products [1].  The future of Sweden’s biofuel initiative looks optimistic, especially given the prolific nature of its fuel!

 

Sources:

[1]http://blogs.scientificamerican.com/observations/2009/10/14/burning-bunnies-for-biofuel/

[2]http://www.time.com/time/business/article/0,8599,1941230,00.html

[3] http://www.peta.org/b/thepetafiles/archive/2009/10/15/Sweden-Burns-Bunnies-to-Generate-Electricityand-Outrage.aspx

[4] http://www.youtube.com/watch?v=rFHnXobZxjY

Coal is still part of the answer

The Fayette Power Project (FPP) is a power plant outside of LaGrange, Texas which uses coal-fired boilers to create steam for turbine generators.  The FPP is a vital part of the energy portfolio of Central Texas.  Of the ~1,600 MW capacity that serves as year-round baseload power, Austin Energy owns 600 MW.  Running at “full steam”, the plant goes through about 1,000 tons of coal every hour to keep up with demand.  The plant keeps about an 80 day supply of low-sulphur coal shipped on trains from Wyoming as emergency backup.  Operators constantly monitor emissions, operation parameters, weather conditions, and production output as managed the Electric Reliability Council of Texas (ERCOT).  Everything from the water discharge temperature to the 6-min average opacity reading recorded by the hundred thousand dollar CEMS (continuous emissions monitoring system) is displayed at the helm.

The FPP was recently recognized as a “gold level” facility under the Texas Commission on Environmental Quality’s (TCEQ’s) Clean Texas Program.  This honor is a result of the plant’s efforts in going beyond the regulatory requirements to reduce NOx and SOx levels. In fact, the plant is currently panning a shutdown of two of the three generators in order to install a new scrubbing system which will remove ~95% of SOx emissions, an increase from their current ~85% control efficiency.  This retrofit is budgeted to cost about $240 million, split between Austin Energy and the Lower Colorado River Authority (LCRA).

As much as the country, and indeed the world, is trending towards renewable energy and the promise of cleaner power, it is undeniable that a) we have a lot of coal, and b) we know how to use it.  While unregulated coal burning in some parts of the world is contributing emissions at an alarming rate, the U.S. has shown that these large utilities can remove a great deal of the hazardous air pollutants (HAPs) we recognize as most detrimental.  Indeed, many coal fired plants spend millions to stay in compliance or do better than required in perfect harmony with the objective of providing reliable, cheap power.  The elephant in the room is the looming CO2 discussion, one that is tricky and somewhat convoluted.  There is no silver bullet solution to collecting and reducing CO2 emissions in a simple, affordable way.  If CO2 control is required, the utilities will be forced to comply, and pass on the cost to the customer.  This may be fine with some people, but it will surely attract the ire of many as well.  Furthermore, the EPA does not have the people power or the regulatory infrastructure to deal with CO2 emissions.  It’s not as simple as inserting CO2 into the list of HAPs and requiring output limits.

It seems that perhaps the best course of action is not to give up on coal because it’s “dirty”, but rather to dedicate more research dollars into controlling or eliminating CO2 from coal-fired operations.  If we can use coal responsibly, and continue to advance new uses and controls, our energy outlook will be clear and promising.  As for now, it will be advantageous to educate consumers about where their power comes from, so that informed decisions can be reached.  The FPP offers tours not as a marketing gimmick to win over skeptics, but as a learning experience to share the behind-the-scenes work that goes into our daily power needs.

How exercise can keep the lights on

This morning, as thousands of runners lined up for the Austin Marathon and Half-Marathon, I couldn’t help but think of how much human power each athlete generated as he or she covered 26.2 or 13.1 miles. What if we could harvest that energy and use it to supply electricity to part of Austin? One of the most widely known examples of human power being used to supply energy is Lance Armstrong’s 2005 Sports Center commercial.

So what does this mean for us? While funny, the commercial is a little bit off the mark. Not even Lance Armstrong could power an entire building. And well, none of us are Lance Armstrong. Sure, mapawatt says Lance can produce 400 to 500 watts while climbing up the French mountains, but he only generates about 250 watts when cruising. Mapawatt’s blogger estimates that he would need 1o of the world’s best cyclists working at their hardest to power his house with max air conditioning. Given the price of electricity, these highly-trained athletes would be making chump change.

In 2008, Portland’s Green Microgym became a leader in the harvesting of human energy, using the exercise of gym members to help power the 3,000-square-foot facility.  Closer to home, Texas State University is using its Student Recreation Center to make students aware of their energy consumption habits. The center’s “human power plant” is the largest in the world and uses 30 elliptical machines to give electricity to the campus power grid. It’s thought that the $20,000 project can pay for itself within 7 or 8 years. How Stuff Works estimates that during a workout, the average person can produce anywhere from 50 watts to 150 watts of electricity per hour, depending on the machine. Some machines even have outlets to power appliances using less than 400 watts of electricity. To put that in context, one could likely power a large TV during a workout but not a refrigerator; lightbulbs would be no problem.

Sure, using human power to provide electricity to our homes is not the most efficient or most cost-effective way of doing so, but the concept inspires each of us to not only put our workouts to good use but to also seriously contemplate our energy consumption. To find ways to make your home human powered, take a look at The Human Powered Home by Tamara Dean.

Power to the People

Ask yourself a question for a moment: How many electrical cords do you use on a daily basis? You charge your cell phone, power your refrigerator, toaster, microwave, television, computer, etc. The infrastructure for electricity delivery in the United States is truly impressive considering how many devices we support on a daily basis. However, as the modern way of life continues to be ever more “on-the-go”, point sources of electrical supply may not be sufficient for consumers that crave longer battery life and less charging.

For true portability and mobility, we all want electronic devices that require little to no time plugged in. Imagine a world where you can walk into a room, and your cell phone or computer is powered without any cords, or any effort on your part. Imagine going on a week long hike and never having to charge your mp3 player in the middle of the woods. Imagine being able to capture energy using the most mundane of sources: a piece of paper or a t-shirt. Everything you are imagining is achievable by today’s technology. Lest this post sound too much like a sales pitch though, suffice it to say that these ideas pose an interesting question regarding our future energy policies and needs.

In the past decade, scientists have developed means for wireless power transmission over several meters, carbon nanotubes spread into paper and cloth that serve as wearable batteries, curtains that shade a room and capture energy from the sun using photovoltaic cells, biomechanical energy harvesters that capture energy from human movement, and the list goes on. While some of these advances are purely novelties at this point in time, it is certain that the future will trend more and more towards mobility and longevity of electrical devices. These inventions represent an innovation in thinking, to the end that one need not bring the device to the wall outlet, but rather bring the wall outlet to the device (in a manner of speaking).

For now, the utility companies still supply the power to the wireless transmitter, and the carbon nanotube paper battery  requires a bath in electrochemicals (manufactured no doubt using utility companies). But if we go down the rabbit hole of speculation: with the advent of more and more technologies each year, if our next generation cell phones are charging themselves from a battery t-shirt, or leeching power from a nearby transmitter, how will the law keep up?

Some homesteads are already generating their own power and selling it back to the grid. What if that same capability were available on a per capita basis? If every person is both using from and supplying energy to “the grid” (if such a thing could be engineered), how can we keep the system fair? If power supply is not consolidated in utility companies, but rather, distributed among the population, will we be able to construct policies to control price, reliability, and equal use? Though none of these products are commercially available, let alone viable, it is also uncertain whether our governmental system and the representatives in control of that system are equipped to handle the complexities involved in such a scheme.  Furthermore, how would the balance of energy concerns (National Security, Environment, and Economics) change? It may a long way off, but as we take energy and power supply back to a home/residence level, and even to a personal level, we find that there is a mix of promise in the potential applications, and uncertainty as to its feasibility and sustainability.