To go solar or not to go solar? Homeowners looking to save money on their energy bills have a number of factor to consider.

It's easy to get excited about installing solar panels on your house – particularly when you find out that state and federal rebates can cut the price almost in half.

But, as we've reported before, you might get more bang for your buck from far cheaper (and yes, far less exciting) fixes. Small things like weather stripping your doors, turning down the thermostat or upgrading your refrigerator, can put a dent in your utility bills.

Even if you've done all that, solar panels still might not pencil out. That's because of something called "tiered pricing", which is how most utilities calculate your monthly energy bills. The idea is that energy is relatively cheap as long as you stay within a certain amount. Exceed that, and you're in the next "tier," where the rate increases. At the next tier, the rate is even higher. The difference between top tier and bottom pier can be as much as 44 cents versus 8 cents per kilowatt hour.

That's why solar panels tend to make more sense for people with substantial energy needs – the big, air-conditioned houses, the heated pools, the multiple flat-screen TVs.

The higher your monthly utility bills without solar panels, the faster those panels will pay for themselves once they're installed. Plus, even if those panels don't meet the complete energy needs of your house, they may be enough to bring you down to a lower tier, where the rate is much better.

If you're interested in making your home more energy efficient, this handy and comprehensive online audit from the people at Lawrence Berkeley National Labs is a good place to start.

Lawrence Berkeley Lab's TEAM 0.5 is capable of resolving individual carbon atoms in the honeycomb crystal structure of graphene. See QUEST's video The World's Most Powerful Microscope for more information. Image source: Nano LettersThe twentieth century’s most important physicist after Albert Einstein is almost certainly Richard Feynman. Known as much for his eccentricities as for his brilliance, he spent his adolescent spare time picking locks, translated Mayan hieroglyphics as an adult, and was one of the few people brash enough to attempt viewing the U.S.’s first atomic bomb test without protective sunglasses. Feynman’s chief scientific contribution was the development of QED, a fundamental and astonishingly accurate description of electricity and magnetism. However, he was also a champion of the practical, and in 1959 gave a gave a prophetic speech at Caltech to his colleagues entitled, “There’s Plenty of Room at the Bottom.” The speech described a rich world of possibilities that could arise if we only applied ourselves toward controlling matter on smaller and smaller scales.

Fifty years later, a new field of nanotechnology has exploded. At the cutting edge, researchers are successfully manufacturing everything from corporate logos to radios that are all small enough to be stacked end-to-end perhaps a million items long across the proverbial head of a pin. The advent of personal computers and smart phones has brought the power of such miniaturization into sharp focus for the general public. In a very real sense, we have all become bottom feeders. Below is a brief progress report on the state of the field.

Microscopes: The old adage “seeing is believing” was not lost on Feynman back in the late fifties. He noted that many of the most fundamental questions in biology could be readily solved if we only had the ability to see the molecules directly. Today, new inventions such as the scanning tunneling microscope (STM), the atomic force microscope (AFM), and the transmission electron microscope (TEM) have all achieved resolution at the scale where individual atoms can actually be seen and manipulated.

Miniature Motors: Perhaps the speech’s most imaginative scenario, due to Feynman’s friend (and graduate student) Albert Hibbs, was the concept of being able to “swallow the surgeon.” Feynman imagined that we might some day be able to construct robots capable of repairing or investigating the inner reaches of an ailing patient’s body. Mixing engineering and biology like this can run quickly into thorny ethical questions. Nevertheless, interesting progress has been made. Researchers in Alex Zettl’s group at UC Berkeley have recently constructed a nano motor, for example.

Information Storage: Using order-of-magnitude arguments, Feynman argued that the Encyclopedia Britannica could be squeezed into a pin’s area if the text were reduced by a factor of 25,000. He offered a $1,000 prize to the first person capable of printing one page of any book at this scale. Tom Newman, a graduate student at Stanford, first accomplished this in 1986 with an impressive reprinting of the first page of Dickens’ classic A Tale of Two Cities. Today, you can buy the book in its entirety for only 1.9 megabytes. For a high-end smart phone with 30 gigabytes of memory, you could perhaps hold 15,000 books within the palm of your hand. Not bad.

Then again, at the extreme limit, Feynman also reasoned that you ought to be able to squeeze the text of every book that has ever been written (now more than 32 million titles according the Library of Congress) within the confines of a single speck of dust. We still have a long way to go.

A technician checks the combustion efficiency and safety of a water heater—an important part of any home energy audit.

I hope I’m certifiable. I’ll find out in about a year when I’ve completed all the training and taken the written and field exams to become a Building Performance Institute (BPI) certified Building Analyst. The certification would allow me to perform energy audits on homes and maybe even get paid for it if I started an auditing business or joined an existing company. The certification would not prepare me to perform energy upgrade measures, such as air sealing and insulating an attic, only recommend the most cost effective ones. Many energy auditors work with a team of trusted contractors who can do the work the homeowner chooses.

My publisher Tom White and I decided that going through the kind of training that we have been pushing in our magazine will give me a more realistic view of the home performance industry, and the people who are just entering it now—the new weatherization workers, and newly minted technicians, contractors, and small business owners who will help build the new green economy. And it’s an excuse to get off my butt and out of the office more often. If I get certified, I’ll need to continue taking classes and have hands-on experience in the field to stay certified.

There are three kinds of certifications for a wannabe energy auditor to consider: certification as a Building Analyst through BPI; certification as a HERS (Home Energy Rating System) rater through the Residential Energy Services Network; or one of many “green builder” certifications that exist nationwide. I think the Building Analyst is the most basic. The training follows closely that of a HERS rater, but HERS raters need to become expert at rating software; it’s a bit more involved. I thought about being certified through Build It Green California as a Green Building Professional. But once I’m certified through BPI, I think it would be a small step to being certified by the other organizations.

Now I am asking what many people in the midst of career decisions are asking. Where do I go for the training and how much will it cost? BPI is in Malta, New York. (Might as well be Malta, the country.) Fortunately, BPI has hundreds of affiliates and approved trainers all over the country. There is also online training, and trainers who will travel to your hometown, as long as you have several people interested in the training. My plan so far is to complete an online training course through well-respected training organization, Saturn Online. That will prepare me for the Building Analyst written exam. I can even take the exam online. The course costs $595, plus about $70 for a book and field manual. Once you start the online course, you have about 8 weeks to complete it, so I can study and take the quizzes and final exam in my spare time—maybe over the holidays. The written exam fee is $225.

But you can’t get all the training you need online, nor would I want to. (Remember me wanting to get off my butt more often?) Saturn also offers three day intensive hands-on field seminars in locations in several locations around the country that culminate in the Building Analyst field exam. I have friends in Portland I haven’t seen in a while; maybe I’ll go there for my field training. The field seminar costs $950. If you want to take the exam at the end of the seminar, there is an additional $350 charge for proctoring. Total costs of going for BPI Building Analyst certification: $2,190. The value of certification: priceless.

The Large Hadron Collider, if located in the Bay Area, would encompass a sizable piece of San Francisco. Image Credit: NASA.In about one month the world’s biggest science experiment, the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland, will once again fire up. So now may be a good time to stop and remember what a stunning and ambitious project this is. Indeed, it becomes hard not to get lost in such an endless list of superlatives once you start noticing. I have gleaned a few below. See CERN’s website for more, or Jennifer Skene’s blog for a great set of LHC links.

She’s Electric: To power a standard light bulb you need 60 Watts (or 15 watts for an equivalent CFL). To power a small house you need an average of about a thousand watts. To run the LHC at full power researchers will need 120 million watts. Alternatively, you could run the LHC, supply electricity to a population the size of Berkeley, or simultaneously bake 60,000 Thanksgiving turkeys. You could only fly three 747 airplanes, though.

Life in the Fast Lane: A fundamental axiom of physics states that no information can travel faster than the speed of light. The LHC’s proton beams are no exception, but their speeds do approach light speed to within a fraction of a millionth of 1 percent. Such velocities defy comprehension. Suffice it to say that if we ever managed to accelerate a person to this velocity, time would warp so much that we could expect her to live for half a million years.

The Long and Winding Road: The LHC’s 17-mile circumference could make it a nice racetrack for a half-marathon, but don’t try racing the beam. When operational, protons will shoot around the LHC more than 11,000 times per second. Even more mind-boggling is the length of wire used in the construction of the LHC’s thousands of superconducting magnets. CERN claims there is enough wire wrapped up in these magnets to trace out more than six trips to the Sun and back.

OK Computer: When operational, the LHC is expected to generate 15 petabytes of data and simulations per year, which amounts to the hard drive space of about 30,000 high-end personal computers. At CERN in 1989, Tim Berners-Lee and Robert Cailliau revolutionized the world with their development of key pieces in the framework of the World Wide Web. The networks being developed to manage the LHC’s expected data have inspired talk of a similar revolution to come.

A Whole New World?: All of these wonders of physics and engineering have been developed for the purpose of one thing: to create a particle smasher with the capability of knocking two protons together with an energy of 14 TeV (trillions of electron volts). This is about the same energy that it takes to pick a grain of salt up off the floor. Compressed into such an acute space, however, it just might lend us insight into the most fundamental properties of our universe.

Now, if they can only get those wires hooked up correctly…

One of 20 solar-powered homes on display at the Mall in Washington D.C. This one is from the University of Kentucky. Credit: Mike MiskellyI was in Silver Spring, Maryland visiting my family last week, and had a chance to visit, with my sister Anne Marie and her boyfriend Mike, the 2009 Solar Decathlon. I’m used to seeing some unusual things on the Mall in Washington, DC—our nations backyard—but was quite impressed by the 20 solar-powered homes arrayed there last Saturday. Students from all over the world designed and built the houses over a two-year period, then disassembled them, transported them to the Mall, and put them back together.

The Solar Decathlon judges these houses in, of course, ten categories.

• Architecture — 100 points
• Market Viability — 100 points
• Engineering — 100 points
• Lighting Design — 75 points
• Communications — 75 points
• Comfort Zone — 100 points
• Hot Water — 100 points
• Appliances — 100 points
• Home Entertainment — 100 points
• Net Metering — 150 points

There are some interesting differences this year, compared to the last contest in 2007. Instead of charging a plug-in hybrid vehicle, as they did in 2007, teams now have to power a home entertainment system. The sponsors of the contest realized that electronic devices, like TVs, make up an ever-bigger share of a typical home’s electricity draw. That’s happening right now, while a plug hybrid car in most every driveway or garage is a thing of the future. A second new feature is that today’s solar houses are connected to the grid. The category “net metering” was not in the last contest. Teams earn points by sending more energy, created by sunlight, to the grid than they use from the grid. The ultimate goal for those of us the home performance field is that all homes become “net-zero” energy homes, or “net-positive,” meaning that the produce as much or more than the grid supplies them over the course of a year. A big problem with solar energy, as well as another renewable source, wind, is that power is created intermittently. Energy storage is necessary, and it is often expensive and not very efficient. With net-zero energy homes, the grid itself provides the storage capacity. When I lived in a Catholic religious community (Holy Cross Priests), the economics of community life were simple—take what you need and give what you can. Same for a net-zero energy house.

I wanted to take a look at the Team Germany (Technische Universität Darmstadt) home, the winners in 2007, but the house was in the process of being judged. Judges don’t announce when they will be visiting a house and which category they will be judging. Teams must keep, for example, the shower water in their solar homes at a precise temperature and flow rate all during the contest. No one knows when a judge will come to the door with a thermometer and flow gauge.

We walked by every house, and stopped at two—with the smallest lines snaking there way out front. (The Solar Decathlon expected as many as 250,000 visitors this year—looks like they made it.) We took a tour of the Iowa State and the University of Kentucky homes. I was partial to the simplicity and the day-lighting scheme of the Iowa house, which made use of simple pine siding and clerestory windows. Mike was more impressed with the Kentucky house, which had some pretty nifty fold up furniture and other creative uses of space. A member of the Kentucky team told us they were inspired by Shaker furniture. The house had wooden chairs, designed in Kentucky and made in Italy, that folded up to be hung on the walls, with decorative features that makes them pleasing to the eye. The Iowa house was made specifically with an older couple in mind. It has a simple layout and it is easy to move around in. Both the Iowa and Kentucky houses had big open showers in the bathrooms, with tiled floors and drainage. Energy efficiency and luxurious (though low-flow) showers can go hand in hand!

As of this writing (Wednesday), Team California, (Santa Clara University and California College of the Arts) is in the lead, with Illinois (University of Illinois at Urbana-Champaign) in second, Team Germany in third, and Team Ontario/BC (University of Waterloo, Ryerson University, and Simon Fraser University) in fourth. The categories of Net Metering, Engineering, and Lighting Design have yet to be judged.

Updates soon!

Kevin Cain, Digital Capture Supervisor for Maya Skies, demonstrates his innovative image-capture process that replaces expensive custom hardware with affordable consumer equipment.On this week’s TV episode of QUEST, we go behind the scenes of Tales of Maya Skies, the new film produced by Oakland’s Chabot Space and Science Center.  The half-hour film about Maya astronomy opens at the center’s planetarium on November 21.

The film is groundbreaking for a couple of reasons.  It’s the first time the Chabot center is using state-of-the art laser scanning technology to create one of its films.  For Tales of Maya Skies, a team of 25 people spent seven weeks scanning the ruins of the ancient city of Chichén Itzá, in Mexico’s Yucatán Peninsula.  This technology is widely used by Hollywood productions because of the flexibility it gives a creative team.  Once they’ve scanned a particular site, they can play with any one of its variables: they can create the illusion that the camera is moving in crazy ways; they can manipulate the light conditions, and they can change the look of the location in any way they want.

The creative team behind Tales of Maya Skies, made up of, among others, Emeryville nonprofit Insight, the San Francisco animation companies Digitrove and Palma VFX, the ARTS Lab at the University of New Mexico, producer Konda Mason and director Jin An Wong, are taking advantage of all the possibilities that the scanning of Chichén Itzá provides.  The audience will be immersed in full-color animations that go beyond showing the ruins of Chichén Itzá as they exist today.  Instead, through laborious historical research, the creative team has reconstructed what the monumental city must have looked like at its peak 1,200 years ago, with temples painted in bright reds, greens, blues and yellows, and incense burning and flags waving atop them.

By using the 3-D digital images created through laser scanners as the raw material for the animations in Tales of Maya Skies, the film is also breaking ground in more indirect, but perhaps even more important, ways.  Insight, the Emeryville nonprofit that oversaw the scanning at Chichén Itzá, as well as the Orinda-based CyArk, another nonprofit that worked on the project, are engaged in scanning irreplaceable sites around the world, documenting them for the benefit of the archaeologists charged with preserving them, as well as for generations to come, which might lose the real thing to natural disasters, war, or the passage of time.  CyArk’s co-founder, Ben Kacyra, has set out to use laser scanners to document 500 sites in five years.

But laser scanners, for all the wonderful detail, speed and flexibility they offer, are expensive.  They can cost anywhere from $10,000 to $150,000.  That’s why Kevin Cain, Insight’s director, has been testing an alternative system that can accomplish the same thing at a fraction of the cost. All the gear he needs is a digital camera, a flash and software, at a total cost of under $2,000.  Here’s how it works.  For every 32-square-foot swatch of an object, Cain takes 10 still photos with his camera and flash.  Then he uses the photos to reconstruct the object based on the brightness of each individual point on its surface.  The system is based on a principle of physics discovered in the 18^th century.  The high quality of today’s cheap digital cameras is what makes it possible to apply this principle to create an inexpensive image-capturing system.

“With this new technique, our ultimate goal is to be able to provide very low-cost, very usable results for archaeologists,” Cain said, “because until the price goes almost to zero, archaeologists aren’t going to be able to adopt it, just given the realities of their field.”  To illustrate those realities, Cain used the example of the work that Insight has done in Egypt for the past decade.  Each year they join a team of archaeologists for their field work at the Tomb of Ramses.  A complete yearly field season costs under $50,000, many times the cost of an inexpensive laser scanner.

Is corn ethanol a poor fit for future U.S. liquid fuel needs? Biofuels have received a tremendous amount of publicity lately as an alternative to gasoline and diesel. An ethanol economy based on sugarcane has helped to boost Brazil into the limelight, raising standards of living and perhaps even contributing to the country’s recent successful bid at the 2016 Olympic games. In the U.S. prospects of corn-based ethanol have piqued the interest of agriculture and oil companies alike. Such unbridled excitement has also revealed dramatic downsides. Brazilian affluence comes at the price of biodiversity as swaths of rainforest are sacrificed to plant new crop fields. Increased American deand for corn was a measurable contributing factor to the recent world food crisis.

The timing, then, was quite appropriate for a panel discussion last week organized by the Friends of Berkeley Lab at the Berkeley Repertory Theatre. Titled “Hope or Hype: What’s Next For Biofuels?” the event, hosted by KTVU’s John Fowler, featured a panel with Jay Keasling, Susanna Green Tringe, and Jim Bristow, three scientists exploring the role that synthetic biology might play in fabricating a better fuel for tomorrow’s autos. The evening consisted mainly of two themes: the relative limits of both crude oil and corn-based ethanol, and an outline of research being pursued to make new ideas practical.

Fossil fuels are unsustainable, a point that saturates public rhetoric each election cycle to the point of ad nauseum. It might be slightly more surprising to learn, however, that fuel based on ethanol (the alcohol found in all common beers, wines, and liquors) may be as bad for global warming as gasoline, perhaps even be worse. When extracted from corn, considerable energy is lost on fertilizers. If that energy was generated using a coal plant, global warming is still a problem. Additionally, ethanol is an unwieldy fuel. It is corrosive, for example, and therefore must be trucked, rather than piped, from one location to another. “I like to say that ethanol is for drinking, not for driving,” Keasling joked as he explained these faults.

The push in the American science community, then, tends to be away from corn-based ethanol and toward something called cellulosic biomass (Editor's Note: see our QUEST video "Beyond Biofuels" for more information). The idea is to make fuels not from corn, but rather from corn stover—plant leftovers after the crop has already been harvested. Alternatively, almost any other organic material ranging from wheat stover to sorghum to garbage could be used if the proper techniques are developed.

There are considerable scientific challenges. Much of the material we might like to use as fuel is tough and woody. Scientists have yet to figure out a satisfactory method for breaking this down, and a great deal of gene-sequencing effort is currently underway with the aim figuring this out. There are also challenges in terms of deciding what product will be generated from these woody materials. At least one idea is to genetically engineer an organism that can transform organic matter not into ethanol, but rather into something more amenable to transport and carbon neutrality.

What should we make of these new efforts? My own feelings are mixed. I enjoy my car, and I love road trips. As Bristow said during the panel, “The reality in the U.S. is that people are going to drive cars. We need liquid fuel.” The current push in biofuels research is tremendously important. The vast majority of energy sources are simply inadequate for powering cars to the extent that the public is accustomed to. The maximum power one could ever expect to obtain from a solar-powered car, for example, is less than 10 horsepower. Even the Geo Metro gets 55 horsepower. The new Volkswagen Beetle gets over 100 horsepower. Electric cars might hold some promise, but at this point it is impossible to tell whether batteries or biofuels will ultimately make a better alternative. These two fronts are also not necessarily exclusive, as the hybrid explosion of recent years has shown.

And yet, for all the excitement, selling the American public on biofuels feels a little like feeding methadone to a heroin addict. We believe that a shift to biofuels will assuage the continued seeping of carbon into the atmosphere. But there are a lot of side effects. The controlled production of biomass requires land, and with that allocation comes a host of ecological concerns. When it comes down to it, there will never be a substitute for good old fashioned belt-tightening.

Visualization of possible chess move sequences (try it here)

Artificial Intelligence has always held a special affinity for games. Chess, in particular, was long considered a realm reserved for exquisite human intelligence: the greatest chess players are called Grandmasters; a large percentage of them are eccentric Russian introverts. Gary Kasparov's defeat, by IBM's specialized supercomputer Deep Blue in 1997, was heralded as a major milestone (he contends the match was unfair). But while the dominance of chess-playing software is culturally significant, does it matter for AI?

Chess, like Checkers, Connect-4, and Go, is a game of perfect information. That is, everything useful for choosing your next move is right there on the board (it would be nice to know what your opponent will do next, but you can assume that your opponent is just trying to make the best possible move too). If you had a computer powerful enough, it could consider every possible next move, every possible response, and so on, and finally deduce, absolutely, how to guarantee a particular outcome. To do this is to solve chess, to answer the question: is it possible for white to force a win? Checkers is solved (both players can force a draw). Connect-4 is solved (the first player can force a win). Chess has too many possible board positions to be solved anytime soon.

Deep Blue can compete with human players by searching many moves ahead, testing all possible combinations, and choosing the next move that leaves its opponent with the worst best option. This approach is called minimax search. Since the computer can't search through to all possible checkmates, it searches to a given depth and scores the resulting board position by the pieces each player still has (roughly speaking, a pawn is 1 point, knights and bishops are 3 points each, a rook is 5 points, and the queen is 8 points). Using this rubric, or heuristic, and searching 10-15 moves into the future, makes for an extremely formidable opponent.

Minimax theory was established by John von Neumann in 1928 and the algorithm was improved in the 1950s and 60s to run more efficiently. Deep Blue contains no general innovation that improves significantly on these now classic techniques. The heuristic for evaluating boards has been refined, and the program has a huge database of well-known openings and end-game sequences-when 5 or fewer pieces are left on the board. Thus, Deep Blue is less a marvel of Artificial Intelligence than of engineering: its success is a direct product of the number of positions it can consider in a second (200 million). This is the Brute Force method of problem solving at its finest.

Most real world problems are not like chess. Political maneuvering, for example, is a game of imperfect information, where each player must guess at underlying motives and resources from superficial clues. The language of political, and in particular war-time gamesmanship, has shifted markedly away from chess… towards poker. Obama tipped his hand, Chavez is bluffing, Ahmedinejad is all in.

And Artificial Intelligence for poker is still far behind humans. The University of Alberta's Polaris system earned a narrow victory at the 2^nd man-machine poker match last July, but the competition involved heads-up limit poker: one-on-one games where the only possible bets are $10 or $20. Compared with the main event at the World Series of Poker, which has no betting limit, and about 10 players at one table, this is something of a "toy" problem. Recent research focuses on how to model opponents-that is, automatically refining the software's understanding of the meaning of each players' bets as information is gathered about how those players play.

Over the next decade, I would guess that poker research, perhaps backed by military funding, will expand significantly. And unlike Deep Blue, poker software that can dominate a table full of professional players, will be the product of significant advances in the field of Artificial Intelligence.

Before You Invest in Photovoltaics, make sure your house isn't haunted by phantom loads.Some Devices Suck Power While They Sleep

When writing about energy efficiency in California, I know that emphasizing heating systems doesn’t carry much punch. I might as well try to get Californians interested in who makes the best deep- dish pizza. (That’s Chicago, of course. Zachary’s isn’t bad though.) Cooling systems are accounting for more and more of a share of residential energy use as we continue to build out from the cities near the Bay in hot dry climates. But overall, when it comes to climate, the inside and the outside of Bay Area homes are pretty much the same for most of the year. But let’s not get soft on energy efficiency! There are other energy users in California homes that threaten to lift us in the future to the level of, say, what a Wisconsin home uses in the winter today.

Miscellaneous electric loads are electric loads other than heating and cooling, water heating, refrigerators, and lighting, and include consumer electronics, outdoor lights, and portable inside lighting fixtures. The U.S. Department of Energy’s Energy Information Agency estimates that these “other” electric loads, along with televisions and office equipment, made up close to 30% of U.S. residential electricity consumption in 2006; this will rise to about 35% by 2020. Part of the reason for the growth in energy use of these devices as a percentage of total home energy use is that homes are heating and cooling more efficiently, with better HVAC equipment, tighter building envelopes, and more insulation.

Rich Brown and Greg Homan of Lawrence Berkeley National Laboratory, measured electricity use in 13 new California homes in 2007 and came up with some interesting results. They metered plug-in devices in standby, off, or low-power mode. Since the homes were not yet occupied, they estimated the annual energy use by using typical use patterns and the energy use of the plug-in devices in active mode, or “on,” measured in other studies. Some of the homes were model homes and packed with appliances and electronics like TVs, and others had only the plug-in devices installed by the builders. Builder installed devices include things like garage door openers, structured wiring, and gas fireplaces. The homes were in four different subdivisions and span the range of typical new construction to super efficient homes with PhotoVoltaic (PV) systems installed.

The builder-installed devices use on average 800 kilowatt-hours (kWh) of electricity per year, or about $80 worth with electricity at a low $0.10 per kWh. That does not include lighting energy. That’s interesting. About half of the energy used by the builder-installed devices is used by devices that are supposed to be turned off, or are in standby mode! That’s very interesting. This is like having a 50-Watt light bulb on 24 hours a day, 365 days a year, lighting nothing.

One of the model homes, the biggest energy user of the 13, used close to 2,500 kWh per year ($250) for two large televisions, a structured wiring panel that uses 20 Watts continuously to power three security cameras and an Internet router, smoke alarms, garage door openers, a washer/dryer, a very big refrigerator, and a few more devices. Add in lighting and that house is a major energy hog, even with super efficient heating and cooling systems and PV panels on the roof.

So what to do? Don’t even think of getting that PV system until you spend some time reducing your electricity load. The PV system you need to meet that load then won’t be so expensive. When it’s time to buy a new appliance, always look for the Energy Star label. Energy Star appliances use about 20% less energy than typical new appliances. Anything that uses a remote control, such as televisions and set-top boxes, or that displays the time of day all day, such as some stoves and microwave ovens, uses energy when officially off. Look for electronic devices that are really off when they say off, or that use 2 Watts or less in standby mode. For your other sleep slurping electronics, plug them into a power strip, and turn the power strip off when you aren’t using the devices. Then look into that sexy new PV system for your roof. More on that in my next blog.

Abengoa's solar power tower, PS10, near Seville, Spain. It is capable of supplying 11 megawatts, or approximately 5,500 households worth of power.Photo: afloresmSouthern California's Antelope Valley is famous for its poppies, luring prospective residents with fiery-orange photographs of the State's most celebrated flower and drawing as many as 60 thousand people each spring to the California Poppy Festival. The region also encompasses the western tip of the sun-scorched Mojave Desert and as a result has recently become the home of one of the most aesthetically striking new designs in alternative energy. On August 5th, the company eSolar flipped the switch on the Sierra Sun Tower, the newest example of what have come to be known as solar "power towers."

Comprised of one or two tall narrow towers surrounded by an enormous field of shimmering mirrors beaming sunlight back up from ground level, these power plants work by essentially the same principle you might have exploited as a child in using a magnifying glass and a hot sunny day to burn holes in the leaves of a backyard playground. A magnifying glass focuses sunlight from a round disk into a single bright dot. A solar power tower's field of mirrors focuses light onto a single water tank high in the air. The concentrated light boils the water, and the steam is used to generate electricity.

In other parts of the world the concept of the solar power tower has gained dazzling momentum as well. Last April, the Spanish company Abengoa commenced operation of a new power tower of its own, dubbed PS20. The power output is still a pittance compared to some of the largest fossil fuel or nuclear plants, but at 20 MW it is currently the largest power tower in existence.

The surge of excitement recently in solar power towers may be grounded on more than hype. Other solar technologies tend to be limited in their promise by cost. Caitlin Cieslik-Miskimena, an eSolar press contact, said that many of the components employed in the company are relatively cheap. She noted, for example, that the mirrors used to collect the Sierra Sun Tower's light are "just a step above a bathroom mirror" in quality. Because they are relatively small, they can also be manufactured to be flat, which is considerably less expensive than the parabolic mirrors used in some other designs.

Nevertheless, solar power towers are just one design in a rich assortment of ideas that people have had for harnessing solar energy. Photovoltaic cells are already used ubiquitously to energize calculators, solar-powered cars, and many satellites, and rapid advances continue to be made in this area. A less flashy form of solar thermal power known as SEGS (Solar Energy Generating Systems) uses curved mirrors to heat long troughs of water. The largest solar power plants in the world today are based on this method. Some companies are even proposing that we exploit solar energy by heating air beneath what amounts to a gigantic clear skirt. (Visit this link for a wild virtual tour of one such proposed plant.)

Time will ultimately tell which (if any) of these will turn out to be commercially viable options as the future marches toward us. Still, we are certain to have a wide array of ideas to explore.