I resent the noise of the printer, printer jams, shaking the toner cartridge, the harsh chemicals involved, and the amount of electricity it takes to print on a sheet of paper. I resent those things with the heat of a thousand suns.

But … just when I believed that I had calcified in my negative stance on all forms of printing, I learned that MIT engineers recently revealed a process they’ve developed to produce printed solar cells.  Their flexible cells can be printed on paper or fabric and folded over 1,000 times without losing efficiency, and they’re not energy-intensive to produce!  I was cautiously optimistic: maybe, I thought, printing doesn’t have to be completely evil?

Photos: Patrick Gillooly/MIT

The creation of typical solar cells involves exposing substrates to intense chemicals and high temperatures, which necessitates a whole lotta energy consumption.  MIT’s new fancy solar cells “are formed by placing five layers of material onto  a single sheet of  paper in successive passes. A mask is utilized to form the cell patterns, and  the entire printing process is done in a vacuum chamber” (Singh).  Fabric and paper substrates weigh less than the glass and other heavy backing materials that are typically used, and researchers think that they’re well on the way to developing scalable cells for use in photovoltaic arrays.

So here’s what I’ll say: the day my office printer can power itself by printing out solar cells is the day I will let go of these negative emotions and learn to forgive.

Click  here to see the technology in action (via Inhabitat).

WU XING:

I have filed MIT’s solar cells under water (because of the gentle process) and wood (because they’re flexible and can be printed on paper). And also, privately, under awesome.

Cited:

Singh, Timon. “MIT Unveils Flexible Solar Cells Printed on Paper.” Inhabitat.com 07/11/11. Accessed 07/12/11. URL.

So given these conditions, it will come as no surprise that researchers led by Peter McGrail out of the Pacific Northwest National Laboratory have been working a new porous nanomaterial that improves an existing process used for refrigeration and air conditioning called adsorption chilling.

Image courtesy colmaccoil.com

All refrigerators and air conditioners make the environment cooler by creating phase changes in a refrigerant so that the chemical absorbs heat.  Most familiar air conditioners use electrically driven compressors to mechanically compress the vaporized refrigerant, whereas adsorption chillers use heat to condense the refrigerant. Evaporated refrigerant “adheres to a surface of a solid, such as silica gel. The silica gel can hold a large amount of water in a small space—it essentially acts as a sponge for the water vapor. When the gel is heated, it releases the water molecules into a chamber. As the concentration of water vapor in the chamber increases, the pressure rises until the water condenses” (Bullis). When that happens, heat is absorbed out of the environment and the newly cooled people rejoice!

Image courtesy emissionless.com

Historically, bulky adsorption chillers have been more expensive and far less efficient to operate than chillers that use electrical compressors.  The flip side is that they are cheap to operate and, if you’re an industrial facility or power plant manager who has massive quantities of waste heat lying around, you can practically run them for free. That’s right people: absolutamente GRATIS.

The new material will make it easier to cool smaller buildings with solar water heaters or waste heat from generators by shrinking the hulking adsorption machines by 75% in size and cutting associated costs in half (Bullis).  Size and cost reductions could make adsorption chillers competitive with compressor driven chillers.

The researchers’ nanomaterial consists of “nanoscopic structures that self-assemble into complex three-dimensional shapes. It’s more porous than silica gel, with a larger surface area for water molecules to cling to. As a result, it can trap three to four times more water, by weight, than silica gel, which helps reduce the size of the chiller” (Bullis). The other interesting thing about the material is that it forms weak bonds with water molecules.  This is a good thing because it means less heat is required to free the molecules (or other refrigerants), making the process of adsorbing and desorbing water 50-100 times faster.

While the nanomaterial definitely makes adsorption chilling more attractive, it’s tricky to match the demand for cooling with the production of heat. For example, if you needed to run the chiller when the sun had set because you lived somewhere humid, you might need a heat storage system (and those can be expensive). Still, anytime things get more efficient a little fairy creature gets some wings!

WU XING:

Cited:

Bullis, Kevin. “Using Heat to Cool Buildings.” Technology Review Online. 03/30/11. Accessed 06/29/11. URL.

No really – it isn’t like learning about the War of Jenkins Ear, where you have to imagine being alive in the 1700’s and fighting with a large group of Spanish and British soldiers and it’s a bit of a stretch. You know what compression when you attempt to balance a pile of textbooks about colonial military campaigns on your head and your neck shortens, and you understand tension because you actually feel it when you pull on a locked doorknob.

Image courtesy wikimedia commons

So far I haven’t worked on any projects like the Denver Airport, where tension and its expression are major elements of the design. But I am working on a competition entry that will incorporate wind-resistant architectural fabric, and research for that project caused me to dig through my lovely ARCHITERIALS submissions inbox where I found product information from Tensotherm with Nanogel®, developed by Birdair, Cabot Corporation and Geiger Engineers.

Tensotherm is a tensile fabric material that insulates like standard roofing, although it can be made translucent if you’re interested in letting light shine in.  According to the product literature, “Tensotherm is comprised of two layers of PTFE fabric membrane with a layer of Nanogel aerogel sandwiched between the two layers. PTFE, or polytetrafluoroethylene, is a Teflon®-coated woven fiberglass membrane that is extremely durable and water resistant; it is capable of withstanding temperatures from -100°F to +450°F, immune to UV rays, and waterproof.” The aerogel layer is as light as a feather and as an insulator it makes whale blubber look pathetic (please do read this post for more on the awesome characteristics of aerogels).

Image courtesy birdair.com

The product is manufactured in Tijuana, Mexico, but unlike strong narcotics arriving daily from South and Central America, Tensotherm is suitable for use as roofing in stadiums, arenas, schools, convention centers, transportation facilities, retail facilities and more. Don’t use it for open-air structures, as it’s not suited for the application.

Image courtesy birdair.com

While it’s hard to know what goes in to the manufacturing process, translucent Tensotherm could contribute to a green building strategy that incorporates daylighting, and if it’s indeed an effective insulator it could reduce heating and cooling loads in buildings.  Another benefit of a lightweight, tensile roof is the fact that support structure can be smaller in size; this reduces expenditures on shipping and installation.  The system produces very little job site waste and the fabric can contribute to the acoustic environment.

Have you used Tensotherm or similar products in your work? Let us know what’s what in the comments!

WU XING:

I have filed Tensotherm under Wood because it’s great in tension.

Scientists have been working with carbon nanotubes (essentially, rolled up sheets of graphene) to encourage solar cells to convert more of the sun’s energy to electricity.  Theoretically, nanotubes “gather more electrons that are kicked up from the surface of a PV cell, allowing a greater number of electrons to produce a current” (Boyle).  More electrons means more power, so it’s a decent line of research to pursue.

image courtesy roselawgroup.com

In practice, however, using carbon nanotubes in solar cells has proved more complicated than one might like for two reasons: “first, the making of carbon nanotubes generally produces a mix of two types, some of which act as semiconductors (sometimes allowing an electric current to flow, sometimes not) or metals (which act like wires, allowing current to flow easily). The new research, for the first time, showed that the effects of these two types tend to be different, because the semiconducting nanotubes can enhance the performance of solar cells, but the metallic ones have the opposite effect. Second, nanotubes tend to clump together, which reduces their effectiveness” (Chandler). Understanding the differences between the two types of nanotubes could be useful for designing more efficient nanoscale batteries, piezoelectrics or other power-related materials.

Image credit Matt Klug, Biomolecular Materials Group

Graduate students Xiangnan Dang and Hyunjung Yi, MIT professor Angela Belcher and colleagues turned to biology for a solution to these nanochallenges, employing a genetically engineered version of a virus called M13, prone to attacking and infecting bacteria.  M13 can arrange and order nanotubes on a surface.  The virus has peptides that bind to the nanotubes, allowing them to separate the tubes so they can’t short out the circuits, and it also prevents clumping. “Each virus can grip about five to 10 nanotubes each, using roughly 300 of the protein molecules. The viruses were also genetically engineered to produce a layer of titanium dioxide, which happens to be the key ingredient in Grätzel cells, a.k.a. dye-sensitized solar cells… This close contact between TiO2 nanoparticles helps transport the electrons more efficiently” (Boyle).

Interestingly, the viruses also make the nanotubes water-soluble, which could lower manufacturing costs by facilitating the incorporation of nanotubes into solar cells at room temperature.  The virus-built structures enhanced the solar cells’ power conversion efficiency to 10.6 percent from 8 percent. That’s about a one-third improvement, using a viral system that makes up just 0.1 percent of the cells’ weight (Boyle). A little help from biology goes a long way.

WU XING:

I have filed this under fire, because the main idea relates to energy.

Cited:

Boyle, Rebecca. “MIT Researchers use Viruses to Build More Efficient Solar Panels.” Popsci.com 04/25/11. Accessed 04/26/11. URL.

Chandler, David L. “Solar Power Goes Viral.” MIT News Office. 04/25/11. Accessed 04/26/11. URL.

Image credit wikimedia commons

Leaves are little factories that power the growth of trees and other plants.  But what if we could use leaves to power our homes and devices? Scientist Dr. David Nocera (MIT) has developed a low-cost artificial leaf that mimics the process of photosynthesis.  He presented the miniature solar cell at the recent 241st National Meeting of the American Chemical Society, stating that the goal of his research is to “make individual homes capable of becoming their own self-sufficient power stations” (Zimmer).  The leaves would decentralize power generation and reduce the need for expensive infrastructure.

Artificial leaves would allow remote, isolated settlements to connect to the rest of the wired world.  In addition, in areas where electric infrastructure already exists, the leaves could function as furnaces, reducing the demand for high-cost oil to heat homes in the winter.  To this end, the Department of Energy’s ARPA-E transformational energy program has partially funded the the research and development of the “leaf” (Zimmer).  Not only that, the artificial solar leaves introduce no additional pollen into the air.

Image credit wikimedia commons

WU XING:

I filed this Solar Leaf under FIRE because it produces useful energy from light.

Cited:

Zimmer, Laurie. “MIT Scientists Create Artificial Solar Leaf that can Power Homes.” Inhabitat.com 03/28/11. Accessed 04/03/11. URL.

Image courtesy physorg.com

Energy start-up NextGen thinks their solar paint has the potential to go 100,000 miles without batting an eye (so to speak).  Their “new breed of cheap solar paint is closer than ever now that the company has raised half of the $1 million it needs to move out of the lab and into the real world. The company’s solar paint is expected to provide up to 40% efficiency at a third of the cost of traditional photovoltaic panels. That’s partially because the paint captures more wavelengths of light than traditional cells. The material, which forms small connected solar cells as it dries, can be applied to nearly any surface–windows, walls, roofs, and more” (Schwartz). It would be easy to repair damaged paint too – you’d just apply another coat.

Image courtesy gliving.com

NextGen isn’t the only organization working on solar paint and spray-on solar cells; others include the National Institute of Standards and Technology, the University of Texas, and the National Renewable Energy Laboratory (Schwartz).  At UT, a research group is making nanocrystals out of copper, indium, gallium, and selenide, dispersing small particles of the inorganic material in a solvent to create an ink or paint that can be sprayed on plastic, glass, and even fabric to create a solar cell. Nanocrystals and nanotubes 10,000 times thinner than a strand of human hair absorb a larger number of light wavelengths onto the photovoltaic cell. The paint can be applied to almost any surface and once dry hooks into the light-sensitive grid to start pumping out electricity (Stefano).

Image courtesy homepage.mac.com

Solar paint technology would be a good fit for something like a government buildings where solar paint could offset energy consumption while giving taxpayers a break, but it should be noted that solar paint is still bleeding edge and “has yet to prove itself in a commercial setting. But if it is successful, NextGen’s paint could help reach the elusive goal of bringing solar power down to price parity with coal power” (Schwartz).  Another issue researchers face is finding raw materials can be used if this technology can be mass produced; copper, indium, gallium, and selenide are not particularly cheap nor are they readily available. Challenges acknowledged, I have a feeling that if this works out we’ll all be slathering our homes and businesses with solar paint and selling energy back to the grid. Then we’ll all go out and buy Lamborghinis.

WU XING:

While it seems somewhat paradoxical, I have filed solar paint under FIRE because it generates electricity, and under WATER because it is a coating.

Cited:

O’Brien, Miles and Marsha Walton. “Getting a Charge out of Solar Paint.” Physorg.com 02/14/11. Accessed 02/16/11. URL.

Stefano, Greg. “Nano Solar Paint: Liquid cells potentially reinvigorate solar power industry.” Coolhunter.com 09/30/10. Accessed 02/16/11. URL.

Schwartz, Ariel. “NextGen Announces Cheap Solar Paint on the Horizon.” Inhabitat.com 04/12/10. accessed 02/16/11. URL.

“The wheel in the sky keeps on turnin’ / I don’t know where I’ll be tomorrow”

Well, okay, I mostly know where I’ll be tomorrow (at the office) but there are a few hours between work and going to sleep tomorrow night that I’m going to play by ear.

Image credit www.moonbeammcqueen.wordpress.com

So now onward to our highly anticipated wheel discussion.  I’m going to assume that the readership of this blog are all pretty fond of wheels due to the fact that wheels make moving things around much easier.  You can use our round and spinning friends to shift people, animals, vegetables, and even minerals.  One thing you might not be using a wheel to move right now is air – but as it turns out, you could be. 

Image credit Airxchange

Airxchange out of Rockland, Mass. has developed an Energy Recovery Wheel designed to supply and humidify/dehumidify fresh air to buildings without simultaneously leaking out all of the inside air that has already been heated or cooled.  “Airxchange energy recovery wheels rotate between the incoming outdoor airstream and the building exhaust airstream. As the wheel rotates, it transfers a percentage of the heat and moisture differential from one airstream to the other. Consequently, the outdoor air is ‘pre-conditioned’ significantly reducing the capacity and energy needed from the mechanical HVAC system.” (Source: Airxchange). 

Images courtesy www.Airxchange.com

LEED and other Green Building protocols award points for increasing natural ventilation in buildings and reducing the energy consumption of HVAC systems.  Airxchange claims that conditioning outdoor air can represent 40% of an HVAC system’s capacity, and that the pre-conditioning ventilation provided by an Energy Recovery Wheel will reduce the load on the system by 70%.  It seems like preconditioning the air with the wheels could make a significant difference.  Does anyone have any experience with the wheels? Hit up the comments!

Airxchange wheels are available in a wide range of sizes for a variety of mechanical systems and come with a five-year warranty. The silica gel desiccant that removes humidity from the air is permanently bonded to the energy transfer media for durability; and cleaning or replacement takes about 15 minutes.  I found a nifty article that explains what’s involved with Energy Recovery Wheel Maintenance.   

WU XING:

I have categorized this under water and fire because it involves dehumidification and air conditioning/temperature changes.

Cited:

“Energy Recovery Wheels.”  Product Roundup.  GreenSource Magazine.  o6/30/10.  Accessed 07/01/10.  URL.