It’s proved to be an invigorating, if whirlwind, few days, but the 2007 Industrial Physics Forum has now officially ended. We hope the entries posted on this blog provided readers with a sampling of the highlights, and a bit of the flavor of actually being in attendance.

My only regret is that there were so many other talks and sessions of interest that I wasn’t able to write about due to the severe time constraints of trying to cover so much substance in a mere few days. For instance, NREL’s John Turner gave an excellent — and realistic! — overview of the progress to date in achieving the much-touted “hydrogen economy,” while his colleague, Mike Himmel, gave biofuels the same hard-nosed treatment. Plasmonics pioneer Nader Engheta of the University of Pennsylvania gave a fascinating presentation on progress to date building circuits with light at the nanoscale, while Bill Bottke ably closed out the entire meeting with a light, yet still substantive, look at Near-Earth Objects and the nature of asteroids.

Most glaringly, there wasn’t time to cover in depth the many excellent speakers featured during Monday afternoon’s session on nuclear energy (including both fission and prospects for fusion energy sources). Public perception of nuclear energy has been quite negative for decades, but attitudes may be slowly shifting as it becomes clear that some form of nuclear power must step in to sustain our energy needs until cleaner alternatives (like fusion, still a good 50 years off) become viable. One doesn’t need to absolutely love the prospect of more nuclear power plants in the world (I certainly don’t), to recognize that they are nonetheless going to be necessary to our long-term survival as a species — just not as a sole energy source.

That last point, I think, underscores the most prominent recurring theme in all the sessions at this year’s IPF: Diversity is going to key. There is no “silver bullet,” no perfect energy source from which we can meet all our future energy needs. We’re going to need everything; achieving the right balance between them all is another major challenge. (In case you’re interested, right now fossil fuels account for 80% of our energy supply; the ultimate goal is to reduce that to 20%.)

I emerged from the meeting significantly sobered at the reality of the challenges we face globally concerning energy and climate change, but also heartened. There are tons of gifted, brilliant and dedicated scientists laboring in laboratories all over the world to solve our problems. They’re largely under-appreciated and ignored. We definitely owe them our thanks and continued support.

Harvard’s Gerald Gabrielse — who kicked off this year’s “Frontiers in Physics” session, which traditionally closes the IPF — has earned his fair share of professional kudos from the physics community for his groundbreaking research at CERN in Switzerland, coming up with nifty new ways of trapping single particles to study them up close and personal.

For instance, back in 2002, his team made science news headlines when they published two papers in Physical Review Letters providing the first glimpses inside an antihydrogen atom. More recently, he’s used similar methods to make the most precise measurements to date of the electron’s “magnetic moment” — a finding that AIP’s Physics News Update dubbed its scientific breakthrough of the year in 2006.

Antimatter, as all good Star Trek fans know, provides the fuel that propels the Starship Enterprise through space, but in the hear and now, creating antimatter and figuring out how to store it in a container without it annihilating itself in the process has proven to be a sticky wicket. Particle accelerators have been producing tiny amounts of antimatter since the 1980s, even making antihydrogen atoms in the 1990s, but those bits raced through detecting instruments far too quickly to make useful measurements.

Gabrielse’s team used something called a “nested Penning trap,” which uses electric and magnetic fields to trap charged particles. It was invented by Hans Georg Dehmelt, who shared the 1989 Nobel Prize in Physics for the accomplishment. Gabrielse’s version consists of a long series of gold-plated electrodes cooled to about 4 degrees above absolute zero (that is cold, y’all!), placed in a very strong magnetic field. Here is a schematic of a basic Penning trap:

When an antiproton enters the trap, it gets captured in the lower part, and as they vibrate and collide with the cold electrons stored inside the trap, they lose most of their energy, ending up suspended in the center of the trap at those ultra-cold temperatures. Meanwhile, positrons are collected in the top part of the trap. At some point they are allowed to interact with the antiprotons to form antiatoms (antihydrogen). The problem is, they annihilate immediately. To get them to hang around a bit longer, Gabrielse added another element: a magnetic trap to capture the cold antihydrogen atoms once they’ve formed and “store” them long enough to make useful measurements.

Since then, Gabrielse’s research has focused on using the new ideas and methods he’s been developing over the past two decades to make more accurate measurements of the electron’s magnetic moment, or “g.” Just like the Earth behaves as if it has a magnet at its core (in that case, almost aligned with the axis of the Earth’s rotation), so, too, does the tiny electron, although in its case, the internal magnet seems to point in the same direction as the particle’s “spin.” The finer we can measure that magnetic moment, the better we can probe the quantum nature of electrons and further our understanding of quantum electrodynamics (QED).

The apparatus Gabrielse’s team built to make their measurement has been described repeatedly as a kind of “single-electron quantum cyclotron.” Here’s AIP’s Phil Schewe describing how it works:

“[They] create a macroscopic artificial atom consisting of a single electron executing an endless looping trajectory within a trap made of charged electrodes… supplemented by coils producing a magnetic field. The combined electric and magnetic forces keep the electron in its circular ‘cyclotron’ orbit. In addition to this planar motion, the electron wobbles up and down in the vertical direction, the direction of the magnetic field..”

It took them 20 years (and 6.5 doctoral theses), but Gabrielse and his cohorts improved the measurement of “g” by a factor of 6 over prior measurements dating back to 1986 (performed by Dehmelt, inventor of the Penning trap). They’ve measured it to an uncertainty of a mere 0.76 parts per trillion, and Gabrielse says they should be ready to announce an even more precise measurement by the end of this year. The number? It’s 137.035 999 710.

As a lighter note after his involved mathematical discussion, Gabrielse showed a doctored photo of a wall at the University of Washington (which also has an ongoing project to measure “g’), in which the value of “g” (as known in 1986) was chiseled — an homage to QED maven Richard Feynman, who once joked that every theorist should put “137″ on the office wall. Gabrielse crossed out the latter part of the value and replaced it with his new value, scrawled in black ink, like graffiti.

Among other things, the better measurements could give us that much more information of the internal structure of the tiny electron, enabling us to discover if, like the proton (made of quarks), it, too, is made of smaller components. “Measurements of the Earth’s magnetism gives us a glimpse into the inner structure of our planet,” Gabrielse explained in a February 1, 2007 article in Physics World (subscription required). “We have obtained a similar magnetic glimpse into another place we cannot travel to or see: a single electron.” On a practical basis, his techniques have led to several practical spinoffs, including a patented solenoid design being used for nuclear magnetic resonance, magnetic resonance imaging, and ion cyclotron resonance.

But the most significant implications, from a fundamental physics standpoint, is that this more precise measurement of the electron’s magnetic moment also allows us to more accurately test/determine the fine structure constant (known to cosmologists as alpha), that number that determines the strength of the electromagnetic force in our universe. Just pop the new value for “g” into existing QED equations, and voila! You’ve got a more refined value for alpha, with an uncertainty of just 0.7 parts per billion. That’s a good 10 times better than available via any other method.

Apart from the scientific importance and recognition of his work, Gabrielse has had the dubious honor of seeing his research reflected in broad popular culture. Bestselling novelist Dan Brown (The Da Vinci Code) set his sequel, Angels in Demons, partly at CERN, and built the plot around the production of antimatter and its potential as a powerful weapon. Quipped Gabrielse of the novel’s premise: “What The Da Vinci Code did for the Catholic chuch, Angels and Demons has done for my research.”

And he scored a first for quantum physics when one of his recent research papers provided fodder for a spoof exchange between actor/comedian Jim Carrey and late-night talk show host Conan O’Brien. The clip has been downloaded over 140,000 times from YouTube since the show aired earlier this year. (It’s a classic! You can find it here.) Gabrielse joked that this pretty much made him “the poster child for obscurity in physics,” but it didn’t seem like he minded too much. If only we lived in a world where more viewers were aware of his name as immediately recognize Carrey and O’Brien. We can dare to dream.

Based on the above opening lines from one of his most famous sonnets, the 17th century metaphysical poet John Donne wasn’t a fan of Le Soleil. Maybe he just wasn’t a morning person, but I suspect the scientists who’ve been working on photovoltaics for decades, struggling to raise conversion efficiency rates a few points at a time in hopes of some day, in the distant future, making it a commercially viable energy source, might share Donne’s frustration. After all, the sun has, to date, proven to be fairly intractable when it comes to harnessing its rays to power our energy-hogging homes.

With all due respect to Donne, it might be time to change our tune. After decades of incremental advances, solar power may have reached that crucial “tipping point” whereby it will suddenly begin to grow and advance at an accelerated rate. That’s the considered opinion of Lawrence Kazmerski, a physicist (and longstanding AVS member, so he was well known to his audience) with the National Center for Photovoltaics at the National Renewable Energy Laboratory (NREL) in Golden, Colorado. “Solar is real, not just in the future, but now,” he insisted.

Kazmerski cuts a colorful figure, and has a strong whimsical streak when it comes to making creative Power Point presentations. He was the perfect person to kick off an 8 AM session on Tuesday, when most of us were still groggy, waiting for the caffeine to kick in. The guy created his very own movie “preview” — complete with theme music — of his talk, in hopes of emulating Al Gore and winning an Oscar one day. Okay, not really, but it a little levity goes a long way to enliven a presentation.

And his whimsy frequently makes a point: He showed a European pro-solar power commercial done in the style of a horror movie, in which innocent London civilians were caught in a downpour of increasingly larger batteries raining down from the sky. The tagline: “970 trillion kw of energy fall from the sky every day. Good we can’t see it. Bad we don’t use it.” The world currently needs 14 TW of total primary energy, and we’ll need an additional 10-15 TW by 2050. Solar cells could be a strong contender to help close that future energy gap — if we can just accelerate the rate of scientific advancement and commercial development even more between now and 2050.

Since its birth in 1953 at Bell Labs, the solar cell has had varying fortunes. It started out strong: one year after Gerald Pearson, Daryl Chapin and Calvin Fuller created a working solar cell in the lab, it had found its way into the “real world.” (For an April 24, 1954 demonstration of the concept, Bell Labs built an erector set ferris wheel powered by solar cells. The press ate it up.) That rapid development curve was due in part to the Sputnik era: solar cells were ideal for powering satellites orbiting in space. The first solar satellite, Vanguard, was launched on March 17, 1958, and it worked for 2-1/2 years. It’s still “the oldest remaining space debris up there,” according to Kazmerski. But on earth, the technology floundered, being neither efficient enough, or sufficiently cost-competitive, for widespread energy generation.

Those early solar cells weren’t especially powerful, but they were incredibly robust. Kazmerski showed an old solar radio from 1957 — it still works! So, reliable, yes. Efficient? Um… they’re working on it. Based on what I’ve heard from numerous speakers at the IPF forum, there’s been an impressive increase in solar efficiencies, and in cost competitiveness.

According to Kazmerski, prices drop 20% with every doubling of capacity — not exactly Moore’s Law, but none too shabby, either.) There are commercial solar cells in production today with efficiencies above 20%, thanks to companies like BP, Saturn, and Sun Power, among others. Photovoltaics is becoming big business. In fact, while companies used to settle for silicon scraps from the semiconductor industry to build their devices, in the last couple of years, demand for silicon in the PV sector actually outstripped the semiconductor industry — PVs now consume half of the silicon in the world. There was even a silicon production capacity shortage as a result of the staggering increase in demand.

The R&D focus is now shifting to alternative technologies, such as thin films, solar cell concentrators, and organics (especially plastics), with quantum dots, thermophotonics, and bioinspired technologies further off in the future. “There’s a lot more out there besides silicon,” said Kazmerski. Richard King of Spectralab reported on their work using multijunction concentrator solar cells to overcome some of the fundamental efficiency limits. He and his colleagues succeeded in building the first solar cell to reach over 40% efficiency — a feat Kazmerski described as “equivalent to breaking the four-minute mile” — with the highest solar conversion efficiency for type of solar cell to date. That’s in the lab, of course, but it bodes well for the future.

So Kazmerski has high hopes for solar based on the latest advancements. He’s further encouraged by growing government support for the technology, although more R&D investment is needed. Japan founded a subsidy program for photovoltaics in the 1990s, and Germany’s Feed-In Tariff Program has made that country the largest PV market in the world today. The US, alas, has the lowest PV market share, being more concerned of late with finding “weapons of mass destruction rather than methods of mass production,” quipped Kazmerski.

But the Bush administration has finally acknowledged the importance of PV technology, and is now providing some $20 billion/year in funding for programs like DOE’s Solar America Initiative. Kazmerski predicts that by 2030, there will be a 500-fold growth in US installed solar capacity.

Of course, as Union College physics professor (and fellow blogger) Chad Orzel points out over at Uncertain Principles, efficiency isn’t the only issue. He reports on a recent colloquium by Peter Persans of Rensselaer Polytechnic Institute, who works on solar cells in his research — specifically, a promising new type using amorphous silicon and “quantum dots.” Here’s Chad’s paraphrase of Persans’ comments on commercial viability:

“In order to meet the energy needs of the US entirely with solar power, we would need to cover 0.2% of the land area of the US with photovoltaic cells, roughly equal to the area of paved roads in the US. And that’s using solar cells with an efficiency of 50%, not too far below the theoretical maximum for a single-layer device….

“[I]n order to build that sort of solar energy infrastructure, we would need to produce and install 2,000 square kilometers of solar cells a year for 20 years. … We currently produce about 200 square kilometers of plastic film a year… [S]o we’re talking about producing complicated solar cells at ten times the rate that we make plastic wrap. That’s what they call a ‘significant technical challenge.’”

Perhaps the most significant “tipping point” for solar has been in public perception. I distinctly recall attending a science fair 20 years ago where a high schooler proudly demonstrated how he could cook a hot dog using solar power. It literally took several hours to accomplish, and even then, the snippets of “dawg” he handed out as samples to passersby were lukewarm and grayish in color — decidedly unappetizing. It colored my perceptions of the potential for solar power for years.

My skeptical views have changed a bit; I now see solar as a viable complementary energy source (I doubt very much it will become our sole energy source). One of the student attendees, Lee, and I were chatting after the talk, and agreed that if we had the money, the land, and the wherewithal, we’d totally install lots of solar panels in our respective custom-designed “dream homes” so we could go completely “off the grid.” (Lee’s keen on a mud floor, too. Apparently it’s all the rage with environmentally conscious young people these days, plus “it looks really cool!”)

One has to take weather variations into account, of course. The solar solution is perfect for southern California, but might be a problem in less sunny environs. So I was pleased to hear that there’s a middle ground, wherein one can install solar paneling as a primary energy source during the summer, funneling any extra energy to the power station in return for “credits.” And those credits could be redeemed during the colder periods. Strikes me as a “win-win” compromise.

Besides, solar panels are kinda pretty, in addition to being practical and environmentally friendly. Call me shallow, but it’s always nice to see good technology in pretty packaging. Architects and builders are far more likely to jump on the solar bandwagon if adding solar panels enhances, rather than detracts, from their “vision.”

There’s been a great deal of uproar this past week over the controversial awarding of the 2007 Nobel Peace Prize jointly to the UN’s Intergovernmental Panel on Climate Change (IPCC) and former vice president Al Gore for their work on raising awareness of climate change and global warming. For all the inevitable politicizing of the issue, what the Nobel Prize Committee’s decision truly augurs is the recognition by the international community that global warming is real, and we’re quickly running out of time to reverse the potentially catastrophic trends.

Honestly? It’s probably already too late for merely implementing mitigation strategies, according to Rosina Bierbaum of the University of Michigan. Nor will simply relying on adaptation strategies be sufficient to deal with the impending impacts of climate change. “Any measures are only going to get more costly and difficult to implement” as time goes on, she said, quoting an old proverb: “It is easier to close the jaws of an alligator when they are small.” Our alligator is entering its rebellious adolescence.

By now, the science of climate change is well-documented, bolstered by a solid accumulation of evidence of global warming that is strong enough to cause the IPCC to declare the conclusion “unequivocal.” And as Bierbaum cheekily observed, this is from a scientific body “not prone to declarative sentences.” There may be minor quibbles about the science here and there, and a few naysaying holdouts, but by and large, the scientific consensus on this is pretty clear.

Even tiny “degrees” of warming matter, so aggressive mitigation — while not sufficient on its own — can nonetheless make a significant difference, she said. One could start by drastically reducing the amount of CO2 emissions, and hence the levels of atmospheric carbon, which are higher than they have ever been (roughly 380 parts per million) over several hundred thousand years. The levels began rising in the 19th century when we began using coal as a major energy source, and they’ve been on the rise ever since, most dramatically in the last two decades.

(One questioner pointed out that when you consider the entire geologic record dating back billions of years, there have been periods with comparable levels of atmospheric CO2, and that eventually a cap would be reached. Bierbaum countered that she’s concerned about the faster rate of change that’s now occurring, since there is far less time for species — including humans — to adapt.)

How much carbon are we talking about, to hold future temperature increases to no more than 2 to 2.5 degrees Celsius higher than the pre-industrial era? Per Robert Burruss of the US Geological Survey, we need to reduce present emissions by 70% over many years, removing hundreds, if not thousands, of gigatons of CO2 from our energy processes, in order to stabilize atmospheric CO2 concentrations at around 500 ppm (it’s around 360 ppm today) — which, by the way, is still kinda high, but should hold the temperature increases to the less catastrophic levels. It’s important to set attainable goals. Just how are we going to do that? Well, the IPCC Special Report on Carbon Capture and Storage (issued in 2005) estimates that geological sequestration of CO2 could eliminate about half of those emissions.

This would involve injecting supercritical CO2 into porous and permeable rock formations some 1 to 3 km below low-permeability seals (to prevent leakage). That includes oil and gas reservoirs, saline aquifers, coal beds, and organic-rich shale. We actually have some experience with CO2 injection since oil companies use it for enhanced oil recovery. So such a scheme is perfectly possible with existing technology and an infrastructure is already in place to build upon. In fact, there are already carbon capture and storage (CCS) projects underway in Norway, Canada, and Algeria; collectively they store about 3 megatons of CO2 every year.

The bad news is that your average 1000 MW coal-fired power plant emits about 4 MTs of CO2 every year. At best, CO2 separation plants will break even. “Clearly, CO2 capture and storage to eliminate a significant fraction of atmospheric emissions will require deployment of new energy systems at an enormous scale,” said Burruss. We could decrease emissions an additional 15% by switching all existing coal-fired electricity to natural gas, but this would require doubling our natural gas consumption — we just don’t have those kinds of resources in the US and importing it from other countries is not a workable solution (as we have learned to our detriment with oil imports). When it comes to energy, there’s always a tradeoff, somewhere.

One of the biggest concerns regarding CCS is identifying sites with adequate storage capacity. Burruss estimates that using low-density storage, US oil reserves could hold around 20.8 gigatons of CO2 — 31.2 gigatons if high-density storage is used. Are you wondering what 1 gigaton of carbon might look like? According to Burruss, it translated into 69.4 trillion cubic feet (TCF) of CO2. For comparison, the entire US gas consumption per year is only 22 TCF, while US natural gas production amounts to 20 TCF. Storing the CO2 emissions from a 1000 MW power plant for 50 years would require a volume equivalent to a two-to-three billion barrel oil field. (Yikes!)

Then there’s the geographical mismatch between the largest sources of those CO2 emissions and the largest oil and gas traps available for sequestration and storage. The largest storage sites are (obviously) located in Texas, the Gulf Coast and southern California, but the biggest power plants producing CO2 emissions are located up and down the Ohio and Mississippi Valley. Transporting all that CO2 into storage adds extra costs to CCS strategies; the other option would be to build new plants at the storage sites and take the old ones offline. Neither option is especially appealing.

We also must be able to insure that the seals maintain their integrity over long periods of time, and to develop mechanisms to mitigate any incidental leakage before the sequestered CO2 makes its way back to the surface. Finally, we’ll need excellent sensors to accurately monitor the CO2 distribution once its stored, and to identify any leakage.

Frankly, I came away from the session feeling a wee bit depressed, convinced that while CCS is a necessary stop-gap measure, it’s not quite up to the task of removing sufficient CO2 emissions to have a significant impact on climate change. That may have been the take-home message. Both Bierbaum and Burruss insist that we’re going to need every possible means of carbon management at our disposal. This includes not just CCS, but also enhanced carbon storage in biomass and soils; shifting from fossil fuels to renewable biomass; drawing electricity from renewable sources like solar and wind, or nuclear power, and continuing to make improvements in generation and usage efficiencies. CCS is only one part of the solution.

Casting about for some small thing you can do to be environmentally responsible? You can always disconnect your doorbell. So says David de Jager, an energy and environmental consultant with E-Concern in The Netherlands (part of a larger organization called ECOFYS). He opened his Tuesday morning presentation by pointing out that an electrical doorbell is pretty much hooked up all the time and therefore draws about 5 watts continuously year-round — more if it’s lit up, and when someone presses it.

This works out to something like .01% efficiency, according to de Jager. In fact, the power required to connect all the doorbells in Europe is equivalent to the power output of two coal-fired power plants, all for a convenience we barely use. Quoth de Jager: “This is idiotic.” Especially for those of us who don’t receive many visitors.

De Jager’s actual presentation had little to do with the doorbell anecdote; that was just his way of emphasizing that the first step in resolving the global energy challenge is to start reducing energy needs, and even seemingly minor things we take for granted can, collectively, add up to a significant amount of wasted energy. he was really there to talk about E-Concern’s POSEIDON project. E-Concern’s stated mission is “A sustainable energy supply for everyone,” and as its name implies, POSEIDON looks to the seas to find that sustainable supply.

Advocates of solar energy like to point out that the sun deposits some 174,000 TW of energy every day onto our humble planet, with 95,000 TW reaching the earth’s surface, of which seas and oceans cover over 70%. Of that, 3,600 TW are converted into winds and tides (the latter amounts to about 3 TW). That might not seem like a large percentage of the total, but annual global energy consumption amounts to about 16 TW. The way de Jager tells it, roughly 9% of the North Sea area could supply all of the North Sea countries with electricity by 2030.

In theory, of course. Figuring out how to harvest that raw energy and convert into usable electricity at low cost — and in a sustainable way — is the hard part.

The oceans already play a critical role in the global energy supply, since a large fraction of oil and natural gas is extracted offshore. The POSEIDON plan calls for using existing oil and has platforms and infrastructure, combined with carbon capture and sequestration capability to achieve “a carbon-free electricity supply” for the North Sea region. The heart of the POSEIDON concept is the construction of an offshore electricity transmission grid connecting onshore user regions with each other, and with offshore fossil and renewable electricity production and storage technologies.

For all his optimism, de Jager’s a smart man, and a realistic one. He knows there are drawbacks to this proposition. There are definitely higher costs associated with wind and tidal energy sources, certainly at the outset. De Jager counters that locating the platforms so far offshore means higher wind speeds and thus higher energy production. He thinks production costs could be as little as 12 to 16 cents per kW/hr, dropping below 10 cents per kW/hr once the system is fully operational.

Then there’s the fact that the platforms are located so far out to sea translates into higher risks. Q7, the offshore wind project currently under construction in the North Sea — and a $540 million investment — has already experienced delays after a cable broke during harsh weather, although no workers were injured. Can POSEIDON’s offshore turbine platforms withstand gale-force winds during major storms? Maybe — they’re certainly figuring that possibility into their designs. Q7 will be an important test case.

It’s tough to tame Mother Nature. Things like tides and winds can be difficult to predict and control. What happens if there is no wind for significant periods of time? Some sort of back-up energy supply is required. That’s why POSEIDON emphasizes an integrated systems approach. “Production, conversion and transformation, transmission and distribution, storage, and final energy demand are not separate elements, but must be considered from a system perspective,” said de Jager.

The offshore platforms and using carbon for enhanced oil recovery are just the initial phase of POSEIDON. In the mid-term, the plan is to develop technologies to draw energy from ocean waves, as well as ways to store that energy until it’s needed. E-Concern has a prototype device called the Wave Rotor to convert wave and tidal energy into usable electricity. Long-term goals include incorporating truly innovative approaches to harvesting energy from wind and water: biomass (extracting energy from sea organisms like algae), osmosis (extracting energy from chemical differences in sweet and salt water), ocean thermal energy conversion, tidal energy extraction, and large-scale carbon capture and sequestration. Eventually all those technologies will be interconnected to ensure a clean, safe, stable and reliable energy supply. Also a cheaper one, since the interconnectivity should reduce system costs.

That’s the plan, anyway. Much work needs to be done to make it a reality, right down to designing improved wind turbines that use direct drive (no gear box), have larger capacities (15 mW compared to today’s 4.5 mW), and more robust carbon fiber blades. New concepts for transmission and transport must also be developed to fully achieve POSEIDON’s mission of cheap, clean, sustainable energy for all. That add ups to a whole lot of R&D, and at the moment, there aren’t too many researchers working on those areas.

De Jager’s youth and enthusiasm are infectious, but I couldn’t help wondering if his enthusiasm for wind energy was related to the fact that he’s Dutch. That’s a region with a history of drawing power from wind and water, and ample natural resources to make schemes like POSEIDON possibly viable. It drove home a point made by an earlier speaker, MIT’s Milly Dresselhaus: the global energy crisis in international in nature, and different energy solutions will be desired by different geographical regions, depending on the resources available to them.

While we’re waiting for new technologies to save the world from itself, feel free to do your small part ands unplug your doorbell. And how about unplugging all those battery rechargers for your cell phone, laptop, PDA, etc., if you’re not actively using them? They belong to the category of “vampire appliances” because most of the energy (95%) is wasted if you leave the charger plugged into the wall, but not into your phone. Nokia even issued a public service announcement to that effect this past May. If 150 people did this for one year, they would save 1 ton of CO2 that would otherwise be emitted into the atmosphere. Little things can make a difference, when done collectively.

One of the standout attractions at Chicago’s Millennium Park is the Crown Fountain. On either side of a reflecting pool are two 50-foot glass block towers. Underneath those glass bricks are LED video screens that, when illuminated, showcase videos of the faces of nearly 1000 Chicago residents, in random rotation, all smiling out at the world while a stream of water cascades over their visages. Every so often, the person in the video will open his or her mouth, and carefully placed nozzles will spray water into the center of the pond — as if the faces were spewing the water directly onto the populace, much like the gargoyles found in older historical fountains. Needless to say, kids love it.

The most central technology that makes the Crown Fountain possible is the light-emitting diode (LED). During this morning’s session on energy efficiency, Shuji Nakamura of the University of California, Santa Barbara, outlined the current status of LED-based solid state lighting, and some of the existing and emerging applications for these ingenious little devices.

LEDS are solid state devices mounted on a substrate of clear plastic, glass or foil. Typically, there is a transparent anode layer that injects “holes,” and a cathode layer that injects electrons when a current is applied across the device. Sandwiched between those two layers are hole- and electron-transporting layers, separated by an emissive layer. It’s the emissive layer that emits light when a voltage is applied. The color of the light depends on the type of semiconducting material is used.

So at heart, LEDS are tiny light bulbs that fit easily into an electrical circuit, except the illumination comes solely from the movement of electrons in the semiconductor material. There is no need for a filament, so they don’t burn out, nor do they get especially hot. Less heat means less energy is wasted, leaving more electrical energy devoted to illumination. LEDs used to be quite pricey, but as semiconducting materials costs have lowered, the technology has become more affordable. LEDs are efficient, cost-effective and long-lasting.

Red LEDs were first created in the 1960s, but it took 30 years for blue and green LEDs to come about (in 1993 and 1995, respectively), and now there’s even yellow LEDs. This means that we can make any color of light we want by mixing the primary colors, or we can add them all together to make white LEDs. The best white LEDs now available use far less power than a 60W bulb. Since lighting is the single largest sector of the electricity consumption in the US, that could translate into substantial energy savings. That’s why scientists like Nakamura believe that solid state lighting is the wave of the future.

Nakamura envisions a world entirely lit by white LEDs, replacing all conventional lighting, from incandescent bulbs and fluorescent lamps to halogen bulbs. The current white LED technology generates light inside a crystal of gallium nitride (GaN), powered by a 3-volt battery. Energy efficiencies are now about 60% (about 150 lm/W) in the lab, and between 25% and 52% in real-world usage. That’s still pretty good: incandescent bulbs are only about 5% energy efficient, and fluorescent lights are only marginally better with 15%-25% efficiency. Whereas conventional lighting has pretty much remained stagnant over the last few decades, LEDs continue to improve, so much so that Nakamura thinks it’s entirely feasible to reach 90% efficiency, or 280 lm/W, by 2011.

This sort of advance is particularly vital to developing countries, where people have no electricity and no light at night. Nakamura briefly mentioned the Light Up The World Foundation, specifically, its efforts to supply a tiny Mubarak village in Pakistan with LED lighting in 2004. Among other things, it’s been a boon to local education, making it possible to hold classes by night.

The biggest limiting factor is cost competitiveness: LED prices are currently ten times higher than regular incandescent light bulbs, and even though they last much longer and are more efficient, consumers still opt for cheaper lighting. But there are useful niche markets, and chances are, you see LED-based lighting around you every day. For instance, the technology is perfect for outdoor garden lights (powered by solar cells), street lights, large video displays like that used in the Crown Fountain (or by NASDAQ, for that matter), and the small screens on cell phones, PDAs, digital cameras, and iPods. Philadelphia recently replaced more than 14,000 of its red traffic light signals with LEDs, for a projected five-year savings of $4.8 million, and now has an LED installation on the Benjamin Franklin Bridge.

Nakamura foresees even more applications in the future. Camera flashes in cell phones, portable desk task lamps, display case lighting in stores, and using LED light to grow plants (on the space station, or on earth) are just a few of the emerging applications. Ultraviolet LED light is effective in killing bacteria, so it’s perfect for air and water purification applications. It could also be used as refrigerator lights to extend the storage life of fruits and vegetables by a week or so — Mitsubishi already has a product along those lines.

Something Nakamura didn’t mention (perhaps in the interests of time) is a subclass known as organic light-emitting diodes (OLEDs) are now blazing their own path to commercial glory. It’s already big business: the market for OLEDs is estimated at around $1.4 billion, expected to increase to $10.9 billion by 2012. OLEDs are organic, so they degrade over time and are easily damaged by exposure to water. But polymer OLEDs bring the advantage of a thin, flexible substrate that can be printed with just standard inkjet printer technology instead of expensive lithographic etching, for example. They’re more easily integrated with other electronic components, too, and that flexibility could one day lead to roll-up displays or even displays embedded in clothing. OLEDs also show a great deal of promise as eventual cheap, disposable microarrays of chemical and biological sensors which light up in the presence of toxic compounds or gases.

In short, it’s a promising technology that still has enormous untapped potential. For those skeptical curmudgeonly sorts who don’t want to just take Nakamura’s word for it, check out these online reports: here’s a DOE study on the promise of solid state lighting, and an OIDA report from 2001 for good measure. Or you can just look around you and see all the places where LEDs are already being used, and realize that the technology is pretty much here to stay. LEDs could soon be the Light of the World.

“What am I, chopped liver?” That’s what the entire field of thermoelectrics (at least as it relates to waste heat recovery) wants to know. In a field of showy alternative energy candidates like biofuels, solar cells, fuel cells, and powerful wind turbines, the challenge of eking out bits of excess energy that would otherwise be wasted as heat to make incremental improvements in energy efficiency seems a bit, well, proletarian. One could almost envision the poor, lonely drudges doomed to try and recover snippets of wasted heat energy for all eternity in Dante’s Ninth Circle of Hell, while Lucifer looks on and snickers.

In short, it’s a thankless task. Small wonder Lon Bell (BSST LLC and NREL) jokingly calls his work in this area “the chopped liver of new technologies.” But now that the great Global Energy Challenge has moved to the forefront of both national and international concerns, there’s been a resurgence of interest in the Little Heat Engine That Could, particular when it comes to waste heat recovery. Bell and his colleagues are finally beginning to get a bit more respect from the general populace at large.

At the heart of Bell’s scheme for recovering wasted heat from vehicle exhaust (thereby reducing CO2 emissions) — as well as from residential, commercial and industrial fuel-fired heating systems, not to mention diesel-powered electric generators — is a well-known (among physicists) phenomenon known as the Peltier-Seebeck Effect (a.k.a., the thermoelectric effect): the direct conversion of electrical voltage into temperature differences, and of temperature differences into electrical voltages.

Let us take a slight historical detour. There was a time a few hundred years ago when thermodynamics was all the rage, even if folks didn’t know that’s what it was called. Back in the 19th century, a little-known French physicist named Sadi Carnot became obsessed with building ore efficient steam engines. His motives were admittedly a bit odd. He was the son of a French aristocrat, and his father was one of the most powerful men in France prior to Napoleon’s ignominious defeat. For some reason, the young Sadi seemed to think England’s superior technology in this area had contributed to Napoleon’s downfall and the loss of his family’s prestige and fortune. But regardless of motive, his research proved revolutionary.

In 1824 he published Reflections on the Motive Power of Fire, which described a theoretical “heat engine” that produced an amount of work equal to the heat energy put into the system. Carnot was no fool: he knew from endless experimentation that in practice, his design would always lose a small amount of energy to things like friction, noise and vibration. His lasting contribution was to set out the physical boundaries so precisely that, after his untimely death from cholera at the age of 32, Rudolf Clausius and William Thomson (Lord Kelvin) would draw on his work to build the foundations of modern thermodynamics in the 1840s and 1850s. Carnot also invented the so-called “Carnot cycle,” drawing energy from temperature differences — the basis of modern-day refrigerators and air-conditioners. (The Carnot cycle also lies behind the popular Dunking Bird science toy.)

Ten years later, a retired French clock maker named John-Charles-Athanase Peltier made a similar “discovery.” (Peltier retired at the age of 30 to devote himself to scientific investigation. Apparently he was a hugely successful clock maker. Either that, or he had a trust fund.) He joined a piece of copper wire with a second piece of bismuth wire, connected the bismuth end to a battery, ad then completed the circuit loop back to the copper wire. When he switched on the battery, one of the copper-bismuth junctions got hot, while the other one got cold. The Peltier Effect can be used to make a rudimentary refrigerator, just by sticking the cold junction into an insulated box — inefficient and not very powerful, but reliable since it has no moving parts.

The Peltier Effect is very nice and all, but Bell’s interest lies in its mirror image: the Seebeck Effect. Three years before Carnot published his seminal work, and 13 years before Peltier’s observations, a German-Estonian scientist named Thomas Johann Seebeck was fiddling in his lab with a metal bar made out of two dissimilar metals (perhaps copper and bismuth), and discovered that if the junctions between them were at different temperatures, a compass magnet’s needle would be deflected. Initially Seebeck thought this was due to magnetism induced by temperature difference, but he soon realized it was creating an electrical current. Furthermore, the voltage was directly proportional to the temperature difference: the greater the differential, the higher the voltage. This is called the Seebeck co-efficient, and it’s crucial to Bell’s work on waste heat recovery.

Thermoelectric (TE) devices are essentially reversible, solid-state heat engines, according to Bell. Apply a temperature difference across a thermoelectric array, and you’ll get electric power; apply electric power, and a portion of the array will cool (create a “heat sink”), while another portion will heat up. They’re rugged, and very low maintenance. Yet apart from select military and space applications, TE devices haven’t played a major role in power generation because they’re not all that efficient in terms of energy conversion (only one-fourth as efficient as an A/C system), plus the materials and systems cost more than other alternatives.

That’s changing, however: Bell and Company have been hard at work in the lab, developing more efficient thermodynamic cycles and improving the overall design and the materials used in such systems. The technology has evolved to the point where lab-based systems are reaching efficiencies of more than 6%, with the possibility of attaining 20% conversion efficiency in the future.

That’s too inefficient for the technology to be used for major stuff like auxiliary power generation, or general cooling and heating, but it’s ideal for some smaller niche applications, says Bell. Things like a desktop heater/cooler, now being developed by a company called Herman Miller; beverage heater/coolers under development by Tellurex; infrared sensor coolers; and scavenging waste heat to both heat and cool car seats, as needed. (Ford, Nissan, and Hyundai are among the automotive companies using TE devices to capture and recycle heat in some car models.) Couple TE waste heat recovery with things like fuel cells and solar photovoltaics, and it could at least enhance the performance of larger power generation systems.

The transportation sector is proving to be the early adopter of this technology. NREL has a $16.2 million program to further develop thermoelectric waste heat recovery schemes for passenger cars to improve fuel efficiency, thereby reducing the use of fossil fuels and associated emissions — perhaps incrementally, but incremental improvements can add up quickly if they’re broadly applied. Simply recovering wasted heat from car, van, truck and bus exhaust could result in 5% to 10% reductions in CO2 emissions.

My shiny Prius features “regenerative braking,” in which the at least some of the heat produced by friction when one brakes is captured and fed back into the car’s battery. I thought it was ingenious when I heard about it, but it’s nothing new to Bell and his colleagues. They’ve been toiling away quietly in the background, the wallflowers of the Great Energy Dance. It’d be nice if they got a chance to take a spin on the dance floor now and then.

I confess: I own a Prius (sometimes dubbed the “Pious” because there’s such a strong — and admittedly irritating — self-righteous streak in some owners). It’s not that I think my little hybrid car will single-handedly save the planet, because despite the improvements in fuel efficiency, I’m still burning fossil fuels and putting more carbon into the atmosphere. But it’s a start, because hybrids are an economic bridge to the electric cars of the future, according to Michael Tamor, an executive technical leader at Ford Research who spoke this afternoon on the re-electrification of the automobile.

“A consumer product will always succeed or fail based on customer value,” said Tamor. Indeed, the commercial success of the Prius — and of the emerging fleet of other hybrid vehicles, from Ford and other automakers — is due in large part to the fact that people believe they are reaping enough benefits (environmentally and in fuel efficiency) to justify the higher price tag. (The high price tag of the planned Tesla all-electric roadster pretty much guarantees it will be a niche luxury item for the foreseeable future, because the critical cost-to-benefit ratio just isn’t there.) With gas prices soaring, and more attention focusing on climate change and the need for energy alternatives to fossil fuels, the time is ripe for the hybrid to make its mark — and pave the way for the next generation of (possibly fully electric) vehicles.

Here’s a fun fact I learned from Tamor: in 1900, Manhattan had as many horses as people crammed onto the tiny island, because steam still reigned supreme and electricity was the hot new up-and-coming technology. The internal combustion (IC) engine wasn’t a serious contender for transportation back then. But all those horses took their toll: New York City got tired of shoveling 1.5 million tons of horse manure off its streets every year, along with over 75,000 gallons or horse urine, and the inevitable carcasses of deceased animals. City officials began casting about for an alternative means of propulsion.

The early prototypes for electric-powered vehicles seemed ideal. Yet somehow, within 10 years, the IC engine completely dominated Manhattan’s transport sector, thanks to a host of advantages that added up to giving better value to the consumer. Sure, the earliest electric vehicles were quiet and clean, but those using the IC engine had greater range, could be instantly recharged, had lower operating costs, and better reliability. The growing availability of gasoline fuel clinched the deal, and internal combustion has been the workhorse of the transportation sector ever since.

GM’s Jonas Bereisa thinks the industry needs another revolution, a “new automotive DNA” to fully make the switch from IC engines to electric propulsion via electric motors, fuel cells and batteries. Moving from the mechanical systems and petroleum-reliant vehicles of the old paradigm to electrical (and electronic) systems reliant on alternative fuels such as hydrogen, will require a complete re-invention of the automobile, he said.

The company seems to be putting its money where its mouth is, investing heavily in R&D to make that paradigm shift. Their progress can be seen in their latest prototype concept car, the Sequel, which provided the company with the much-needed proof of principle that they could viably engineer fuel cells cars. GM is unveiling its Chevy Equinox fuel cell car next week, and in the interests of learning how the model fares under real-world driving conditions, over 100 of the cars are being provided to test drives in California, New York City, and Washington, DC. Next on the design board is the planned Chevy Volt, a concept car that will come in two iterations: an extended range electrical vehicle, and a fuel cell vehicle.

Of course, one will need easy access to refueling stations, although Bereisa points out that most of us are closer to a hydrogen production facility than we think. Oil refineries have moved to heavier petroleum products, with a corresponding need for hydrogen in the refinement process, so the oil industry has invested heavily in building hydrogen facilities all over the world; they are particularly dense in Europe. “We have the infrastructure in place, we just need to expand it,” he said, although there’s still the challenge of how to get it into the hands of the consumer via fast refueling.

Ford has chosen to attack the problem from two sides: decrease fuel consumption, and increase renewable sources of non-fossil carbon, such as ethanol or biodiesel. Even with that two-pronged approach, says Tamor, we’re still left with an energy gap, and that’s where the more expensive fuel cells could play a role (GM is betting on it). But he thinks we might be able to close the gap with the plug-in hybrids currently under development, if we can get the right confluence of factors. “It will take a combination of battery cost breakthroughs, stable electricity prices, and extremely high gas prices to restore the plug-in hybrid’s cost advantage,” he said.

To be competitive, the plug-in hybrid must have a 400-mile range, a system mass of less than 200 kilograms, and a refill time of 10 minutes or less. The technology doesn’t yet come close to those targets, alas: the lightest lithium-ion batteries are still too heavy, and it’s not yet feasible to build a refueling station with the power generating capabilities to recharge four vehicles at once in less than 10 minutes each. The battery value just isn’t there either: Tamor estimates it needs to be about one-tenth the current price. Still, most drivers in the US make daily trips of 50 miles or less, at least according to Real Vehicle Usage surveys conducted in Atlanta, Baltimore, and Spokane, WA. A plug-in hybrid could be just the ticket for those kinds of drivers.

The semiconductor industry has been dominated by “Moore’s Law” for decades. Every time it seems we’re about to reach the threshold beyond which chip size and density can’t possibly go any further, some new breakthrough prolongs the lifetime of the silicon chip just a little bit longer.

Too bad we’re not making comparable strides in the energy sector, because without sufficient energy, how will those sturdy little silicon chips be able to run? Kicking off the 2007 Industrial Physics Forum with an overview of the energy landscape, MIT’s Mildred Dresselhaus recommended that we “Think big and go small,” and called for “a Moore’s Law” for energy efficiency. “A few percent in improvement means nothing” in the grand scheme of things,” she insisted: “We need an order of magnitude improvement.”

The numbers she cited are quite sobering. Global energy demand is expected to double by 2050, and triple by 2100 — faster than the world population as a whole, which stood at 6.5 billion in 2005 and is expected to reach 8.9 billion by 2050. The energy demand growth rate is so steep, there’s no way we’ll be able to meet those needs if we continue to draw 85% of our energy from fossil fuel resources. Those resources are projected to peak around 2037, at which point we will have used up some 90% of known oil reserves. It’s just not sustainable.

The good news is, there are emerging alternatives, including nuclear power, solar, wind, biomass, and geothermal energy strategies. The bad news is, those alternatives aren’t advancing fast enough in terms of meeting the necessary targets of energy output, cost efficiencies, and the like.

Dresselhaus emphasized repeatedly in her talk that no single energy solution will suffice; we need a diversity of sources to close the gap between available sources and our future energy needs. But her comments just on the solar power option alone illustrate the magnitude of the energy challenges we face. “Solar energy is very plentiful, but we’re not using much, and [the existing technology] is not competitive on a cost-efficient basis,” she said.

The sun deposits mind-boggling amounts of energy to Earth every day: a whopping 1.2 x 10terawatts. The 7.8 magnitude earthquake that leveled San Francisco in 1906? The energy of that event is equivalent to a mere one second of sunlight. A day and a half of sunlight is equivalent to 3 trillion barrels of oil. So why doesn’t everything run on solar power? Sadly, harvesting solar power is not that simple, because there are always energy losses to contend with when harvesting the sun’s energy for practical purposes. It’s basic thermodynamics, the Great Cosmic Killjoy of physics. Today’s solar cells operate at about 32% efficiency; with a bit of ingenuity, Dresselhaus thinks we can get them up to 50% efficiency, but even to achieve that much will require truly revolutionary advances in photovoltaics.

Solar cell technology is also more costly, at the moment, than fossil fuels, which might explain why photovoltaics currently only account for .0002 terawatts of world energy needs; the goal is to reach 1.5 terawatts by 2050. To do that, said Dresselhaus, we will need to decrease the cost of photovoltaics by an order of magnitude. We’ll also need to figure out more efficient ways of storing the sun’s energy until it’s needed for use. And that’s where the “go small” component of her strategy comes in, because nanoscale materials will play a critical role. For starters, there is a higher surface to volume ratio in many nanomaterials, the better to promote catalytic interactions to yield usable energy. To that end, scientists are already working on quantum-dot based solar cells, as well as nanostructured thermoelectric materials.

Dresselhaus also name-checked such promising sustainable energy sources as hydrogen — the focus of a major initiative launched in 2003 by the Bush administration — thermoelectric conversion, modifying the biochemistry of plants and bacteria to produce more efficient biofuels (“designer plants for designer fuels”), artificial photosynthesis, and solid state lighting. The latter, she said, has come the closest to achieving a kind of “Moore’s Law’ in the energy sector in terms of progress in energy efficiency and cost competitiveness, although some challenges remain.

Policy-wise, she called for road maps setting out the challenges and target goals for each energy source, and emphasized repeatedly the need to promote international collaborations. “Energy is a big, complex system,” she concluded, and we need to mind the gap between existing resources and future needs. If we want our ever-smaller computers to keep running, we’ll need to look to a more sustainable mix of energy resources. Starting… now!

Greetings from sunny — okay, slightly overcast — Seattle, Washington, where for the second year in a row, the annual meeting of the American Vacuum Society also hosts the Industrial Physics Forum (IPF). This year’s IPF theme is “The Energy Challenge,” with a host of distinguished speakers on hand to explore the ways in which we might power the world of tomorrow — and do so in a clean, safe, cost-efficient manner. Tall order, but fortunately scientists aren’t ones to run away from a challenge.

I’ll be posting highlights from the sessions periodically here over the next few days, ably assisted this year by three members of the Society of Physics Students: Shane Landey of Colorado University in Denver; Lee Massey of the University of Wisconsin, River Falls; and Justin Stimatze of Georgetown University in Washington DC.

Among the topics we’ll be tackling: the latest in hydrogen-fueled cars, better fuel cells, and low-carbon impact fuels; solid state lighting and photovoltaics; the status on fusion power and improvements to conventional nuclear power plans; and renewable energy sources such as solar cells, biomass, and wind power. The IPF conference closes on Tuesday afternoon with the traditional “Frontiers in Physics Session,” outlining some of the cutting-edge physics research taking place that will lead to the revolutionary (one hopes) technologies of tomorrow.

We hope you’ll check back over the next few days as we post reports on the meeting’s progress.