Solar cells from donuts and tea

It's been posted everywhere, and it doesn't acknowledge the source of the idea as far as I can tell, but here's a fantastic little video about making solar cells out of materials derived from powdered donuts and tea. He isolates titanium dioxide from the powder and sensitizes it with anthocyanins from a Tazo passion hibiscus tea. Here is a high school teacher doing the same project, with numerical data & extra science that you can't really fit in a video.

Still, I love these sort of suprising projects.

The perfect match: Southern California and Solar Energy

This is great news: Southern California Edison is going to build 250MW of distributed photovoltaic solar energy across Riverside and San Bernardino counties on top of large commercial buildings. These are inland valleys that get little marine fog and lots and lots of sun. The power company will own the panels and sell the power back to the commercial sites that host the panels, providing distributed power. It helps solve the great bottleneck of transmission between the power sources in northern California and the heavy A/C users in the south. The only caveat is that the inland valleys are also generally the smoggiest places in L.A. Improving the air quality will also improve the energy yield, but generally the smog is from automotive sources instead of coal plants--the coal plants that Southern California Edison use are all further east, polluting the desert.

Let's expand this to all the sunny cities of the desert: Las Vegas, Phoenix, Tucson, Albquerque, El Paso, and yes, even San Diego and Los Angeles. Let's even just start with solar water heating.

Southwest solar meets the New York Times

Turning Glare into Watts.

If large numbers of plants are built, they will eventually pose some problems, even in the desert. They could take up immense amounts of land and damage the environment. Already, building a plant in California requires hiring a licensed tortoise wrangler to capture and relocate endangered desert tortoises.

Often in desert construction the entire lot is bulldozed for convenience and it doesn't have to be. This applies to one acre lots (from personal experience) to larger plots as mentioned. The compressed surface often only allows the invasive non-native Russian thistle (aka tumbleweed) to grow. I've never seen the dominant native vegetation in the Mojave, the creosote bush, grow back in disturbed plots.

UV coating on thin film solar cells

You might have read about a UCLA team that's developed a way to reduce UV degradation of thin film solar cell systems. They claim a patent for a "photon converting material" that converts UV into a lower-energy wavelength light. Yeah, it's actually just a fluorescent dye. Adding fluorescent dyes to CCDs has been common practice to increase the terrible efficiency of CCDs in the UV. I can't see what new non-obvious thing here needs to be patented.

This is the sort of thing a smart journalist needs to ask questions about, instead of taking a press release at face value.

http://technology.newscientist.com/article/dn13372-green-invention-special-longlife-solar-cells.html
http://www.treehugger.com/files/2008/02/solar-cell-coating.php

Incoming asteroid--errr, satellite

Astronomers at the Catalina Sky Survey near Tucson discovered an object on November 7th and when the orbit was calculated it was a Near Earth Object (or NEO) and would barely pass by Earth in only five days time. By barely, it was calculated at only a Earth's diameter away--a little under 8,000 miles.

Photometric measurements suggested the object was 20m in diameter, which is pretty big as things go--the Meteor Crater parent body was estimated at 30-50m.

But as Russian astronomer Denis Denisenko noted on the MPML, the object had a peculiar orbit: it passed quite close by Mars at nearly the same time as an ESA orbiter called Rosetta. See a view at Mars here. And, Rosetta happens to have the largest solar panels short of the ISS, two 14 meter long panels that make 64 square meters in total, matching the expected brightness of the object. Sure enough, Rosetta is due at Earth for a orbit changing interaction with Earth in five days so it can rendezvous with a comet in 2014. The people in charge of maintaining minor planet orbits decried the lack of coordination between the artificial satellite organizations and the minor planet community--as satellites are launched it's easy to watch them go away, but the NEO watchers are rightfully concerned about inbound objects, and the data about spacecraft outside of near-Earth space is skimpy.

Philosophia Naturalis #11

My post on the opening of Nevada Solar One got mentioned in Philosophia Naturalis #11, hosted at Highly Allochthonous. Philosophia Naturalis is a collection of blog posts about the physical sciences, hosted each month at a different site.

Nevada Solar One

image from Solargenix

A large solar thermal energy plant is now online in the Eldorado Valley, just south of Las Vegas, creating up to 64MW of power from a 400 acre site covered with reflective troughs and tubes filled with brine (I was tempted to write "a series of tubes"). Molten salt is used to retain excess energy for later release when it freezes back into a solid. A view of the under construction site is here. The site is located conveniently next to a very large power distribution network hub.

The heated tubes are interesting in their own right. Schott makes them--a vacuum insulated glass tube with a blackened steel tube in the center. The outside has an anti-reflection coating, and the steel coating is made to reduce IR thermal emission: visible and near-IR go in, steel heats up, but it can't radiate thermal IR out. The result is 95% of light is absorbed; but only 14% of the IR is emitted. Keeping everything sealed at temperatures between freezing and 750F is difficult, and one of things Schott did was make a special glass with a coefficient of expansion the same as steel.

The second major solar energy project in southern Nevada is a 15MW plant at Nellis Air Force Base, using photovoltaic cells directly creating electricity. The system will track the sun, and it sits conveniently on an old landfill, land previously unusable.

In addition to these two major projects, there is a little over 3MW of solar energy projects in southern Nevada, with most of the total from the Las Vegas Valley Water District. See the status of Nevada energy projects in this 2007 report

Renewable decentralized solar energy continues to have arbitrary limits placed on it by law, keeping power companies monopolies in place. How requiring power companies to produce 15% of their power from renewables in eight years while disallowing much locally-produced power sources works together is beyond me.

From Friday's Las Vegas Review-Journal:

A lobbyist for the Clark County School District said she was pleased that the proposal increased the maximum amount of solar power the district can generate to 2 megawatts compared to 570 kilowatts. ...

But per school limits are 50 kilowatts.

Conklin liked that limitation, because it encourages the district to install solar plants at more schools, giving more students an opportunity to see how solar power works.

... Under the bill, customers may qualify for net metering if they generate as much as 100 kilowatts on their site, up from 30 kilowatts.

Nevada Solar One is static--a cheap low-maintenance support structure that resists wind damage very well (EDIT: someone corrected me: it's a one-axis tracker). The Nellis project uses tracking systems to maximize the solar gain. What is that gain? It depends a lot: on how much Sun you get, how long your days are, and how cloudy it is over the year. In Las Vegas, for instance, the overall solar energy received with a tracking system is about 7.1kWh per square meter per day averaged over the year. A static mount would get 6-6.5kWh. It doesn't sound like a lot of difference, but that's a per day number for only a square meter: multiply by 365 and for the size of the project, and it adds up. For single sunny months, tracking wins by far--over 9kWh per day in June in Vegas compared with 7 for a static system. It's interesting to note the incredible values created on the North Slope of Alaska--nearly as much as the desert Southwest--merely from having the Sun around for 24 hours a day.

Why aren't we doing more to power the cities of the Southwest with solar? Even just using solar water heaters in the warm months and smart skylights for daytime lighting would change energy use forever there.

A video describing Nevada Solar One, including some interviews, is available here.

And finally,
click here for a more amusing video about the 360MW of solar energy projects in California.

Shuttle launch on June 8th

The upcoming Shuttle mission starting on Friday evening is a big construction project on the ISS, to move and add a large solar array to the station. The ISS currently looks a little lopsided; here's an image from December 2006:



Here's an artist's rendition of the planned work; you can see the second pair of solar arrays added. They are removing the odd array on the top; one thing I couldn't tell from the press release was whether they are storing it up there and redeploying it at a later date or bringing it back; the full ISS would have eight solar panels on each side.



I picked this image up from the STS-117 Press Kit

National Energy Policy

Sam, Colin and I were talking about biodiesel last night as walk-home talk fodder. It's a great thing--a no-modification substitute for fossil fuel diesel. Every gallon of biodiesel does nothing for carbon or pollution emissions or energy use, but reduces our dependance on Middle-East oil by a gallon. Naysayers complain about its sluggishness in cold weather, but this is standard behavior for #2 diesel, and complaints from Minnesota about it are related to poor-quality vendor biodiesel. Get companies that care about (or are forced to) producing a quality product and the clogs will stop.

The New York Times is reporting that President Bush will be talking about national energy policy in tonight's State of the Union. As usual, instead of dealing with proven strategies for increasing efficiency, he will argue for more pie-in-the-sky ideas that are far off. Far off enough to dump large subsidies into corporations for research of bad ideas, like the hydrogen car. Remember the hydrogen car? Instead of increasing today's automobiles' gas mileage by a few MPG by raising the CAFE requirements and getting the huge exemption of SUVs into the fold, he dropped them and asked for research into a non-proven, non-existent technology. Drop the idea of fuel-cells for cars. Stick them in houses, where they would actually work great.

It's a standard technique--drop funding for some project that could work but isn't on their party's agenda (cough hybrids cough). Claim that you have to use that money to research for something in the future like the hydrogen car. Watch as corporations use that R&D money to do nothing important. Quietly drop funding a few years later, claiming hydrogen cars weren't feasible. Congratulations! You've killed funding for the thing the other party wanted, without people noticing. Sound familiar, NASA? Drop science funding for "Manned space exploration of the Moon". Quietly kill that in a few years. Science funding never comes back.


The government should do three things for the energy security of the United States.
1. Spend on Research and Development, and avoid throwing money at corporate welfare. Science is very important for the long-term future, and its funding should never be in jeopardy.
2. There is nothing inherently wrong in nuclear power--it's cleaner than coal (yes, a point for another post). We need new energy sources as use naturally increases with time, and it's the most efficient way.
3. Reprocess nuclear fuel and recover the huge amounts of wasted U-235 and Plutonium that are just left to rot. Reprocessing would drop the need to immediately build Yucca Mountains every twenty years.
4. Encourage inexpensive solar energy development. Why haven't we powered Las Vegas, Los Angeles, San Diego, or Phoenix via solar power yet? Just using simple solar water heaters is a cheap and great start. My family heated our water for years with solar--why can't everyone in the southwest do this?
5. Biodiesel is a great option to immediately encourage--a direct replacement for diesel, especially in warm climates. Subtracting the national cost of supporting Middle-East oil, it becomes cheaper than you think.
6. Increase the efficiency of cars, and continue tax credits for all hybrids, including popular ones, but don't let the manufacturers trade efficiency for power.