Microwire Photovoltaics at Caltech

I went to this year’s second Everhart Lecture yesterday by Josh Spurgeon, who is working with Harry Atwater and Nate Lewis, trying to develop cheap, scalable solar cells.  As with most of the Everhart Lectures, it was a very well presented talk.  Unlike many of them, it was directly relevant to a real-world problem: how can humanity continue to utilize on the order of 10TW of power, without changing the composition of the atmosphere (see Nate Lewis’ excellent presentation for more information). The ultimate solution to that problem will almost certainly involve directly capturing incident solar energy, because the potential resource available is both vast and relatively concentrated, when compared to other sources of renewable energy.  But solar has two very serious problems today: it is expensive (both in absolute terms on a per watt installed basis, and in an up-front capital expenditure sense), and it is not available when the sun isn’t shining.  Whatever the solution looks like, in order to scale up to 10TW, it needs to use only earth-abundant, non-toxic materials.  In semiconductor photovoltaics then, silicon probably has an unassailable lead.  It’s the second most abundant element in the Earth’s crust, and it’s about as toxic as sand (though silicon semiconductor fabrication has serious toxicity associated with it and certainly needs to be made closed-loop).  Exotic materials like cadmium-telluride, and copper-indium-gallium-selenide (CIGS) are unlikely to scale to tens of terawatts, simply because of the limited availability of elements like indium and tellurium.  Additionally, owing to the vast silicon microprocessor industry, we are much better at micro and nano-scale manipulation of silicon than any other material on Earth (ignoring for the moment biological systems).

Continue reading Microwire Photovoltaics at Caltech

Shared Links for Apr 28th

Shared Links for Apr 17th

Shared Links for Apr 14th

When the Rivers Run Dry by Fred Pearce

When the Rivers Run Dry is a kind of modern, global Cadillac Desert, looking at present and future water issues around the world.  I think in the end it was too ambitious, looking at too many individual situations superficially, without going into the details on how they came to be the way they are (which Cadillac Desert was able to do, since it focused only on the American West), and also without drawing enough insightful generalizations from the many different cases the author studied.  It ended up feeling mostly like a dreary litany of mistakes painstakingly repeated in nation after nation, decade after decade, apparently without any learning going on.  Often these projects were funded by the World Bank and other international “aid” organizations, or by powerful central governments.  In both cases, the motivations often turned out to be short sighted and political or financial and had little to do with good engineering, productive agriculture, fisheries, or long term stability.

Continue reading When the Rivers Run Dry by Fred Pearce

Shared Links for Apr 10th

Shared Links for Apr 8th

  • The secret, social lives of bacteria – Cooperative behavior between bacteria, both inter and intra species, coordinated via chemical messages. Behavior like "should we make light?" and "should we kill the host now?". Scary, awesome, and a beautiful system to investigate with algorithmic game theory! (tagged: cooperation biology technology bacteria science )
  • Computational Legal Studies – More people using machines to understand politics. A whole new class of dual use technology. Propaganda or transparency? Manipulation or clarity? Unauthorized social networking. (tagged: transparency technology government law )
  • Public Private Investment Partnerships a la Enron – Giving banks the ability to both buy and sell into the toxic asset markets being set up under PPIP is a recipe for market gaming in the tradition of Enron, as outlined in this example. Great, a trillion dollar Enron! (tagged: finance bailout economics policy enron ppip banks )
  • The New Nostradamus – Bruce Bueno de Mesquita uses large game theory simulations to try and predict the outcomes of complex negotiations involving many parties, both economic and political. Sounds interesting. Also sounds a little bit like bullshit. But apparently the CIA did a prospective trial (no backtesting bias) and found that the models made accurate predictions something like 90% of the time, when the analysts providing the inputs to the model made wrong predictions. Not so surprising that computers are better at synthesizing massive logical datasets into an outcome. The hard part seems like it would be getting the right inputs, and also trusting that people behave rationally, and (perhaps) know what's good for them. (tagged: economics politics science math prediction gametheory technology )
  • Ice Shelf Instability Backgrounder – A good backgrounder from last summer on the Wilkins Ice Shelf (which has just collapsed), and shelf dynamics in general, with links to the relevant literature. None of this is quite as sudden and shocking as the media reports have made it out to be. (tagged: climate antarctica ice shelf )

Shared Links for Apr 6th

  • Sing a dirge for the unused adipic acid – An essay on the unpleasantries of being lab safety officer, and the sentimental attachment that scientists have to their expired reagents. (tagged: science chemistry lab safety )
  • Does carbon-eating cement deserve the hype? – A process for manufacturing cement which sequesters CO2 (instead of releasing it) has been recently hyped. Chemistry looks dodgy though, and the company (Calera) is not forthcoming with details, or even a gross inputs/outputs for their miracle black box. Caveat emptor. (tagged: carbon climate technology cement )
  • Self Irrigating Planter Resources – A nice little gathering of pointers to information on DIY self-watering planters. Still trying to figure out how one might be able to use tires to make one of these…. (tagged: gardening technology food sustainability urban )
  • The Case Against Breast-Feeding – Backlash against the relatively new social imperative (in the west) that women must breastfeed to be good mothers. I think the real issues are that we haven't structured our society and its expectations to meaningfully accommodate having children and equitable peer spousal relationships. I agree there's something broken, but I don't think it's breastfeeding. And I feel like it's another example of the Newtonian hangover… we're so used to being able to figure things out authoritatively, a la Newton, that we almost don't know how to deal with planning around and purturbing complex systems like the climate, or ecologies, or economies, or agricultural systems, or genomes, or nutrition… which we depend on, but don't understand fully (and because of their chaotic nature, may never understand fully. We're used to Apollonian systems, but actually we live in a Dionysian world. (tagged: science food children health breastfeeding society )
  • Collapse Of The Ice Bridge Supporting Wilkins Ice Shelf Appears Imminent – This ice shelf is 3x the area of Rhode Island. It's already floating, so it won't have any effect on sea level as it separates, but that's a lot of ice. Wish we had better time series for this kind of observation. Really need the best long term Earth monitoring system we can build. (tagged: environment climate antarctica ice )
  • The strengths of the academic enterprise – A great essay by Dijkstra on the nature of academia, and the problems of cooperation between entities with dramatically different time horizons. Who knew he was interested in things other than graph theory? (tagged: academia science sustainability education technology )

Dijkstra, the Buxton Index, and the Prisoner’s Dilemma

EW Dijkstra, the computer scientist, was fond of using a metric called the “Buxton Index“, which conveys the timescale on which an individual or institution makes its plans.  He thought that a lot of failures to cooperate, and other kinds of conflicts, were ultimately due to different actors having different time horizons.  Here are three of his short essays mentioning it:

It’s interesting in the context of, e.g. the Prisoner’s Dilemma, in which only an indefinite (or infinite) timescale can reliably result in cooperation (as detailed in Robert Axelrod’s book, The Evolution of Cooperation).  It certainly seems like we should have some metric of this kind in mind when considering the behaviors of various institutions.

Dijkstra notes that interestingly (at least in the west) virtually all of the institutions which are more than 500 years old are universities (two churches and two governments also qualify, out of 66 total).

I think its funny that Dijkstra was essentially blogging, by fountain pen, for decades.  He wrote out hundreds of these short numbered essays longhand, and sent copies of them to friends, who then copied them, and sent them on, etc.  He kept doing it this way even after everyone had e-mail!  I had no idea he was such an interesting guy.

Shared Links for Apr 3rd

  • Stealing Commodities – Our infrastructure is (unwittingly) built around the assumption that the materials it is composed of are, and will remain, cheap, and not worth the trouble of stealing. If this assumption breaks down, copper power lines start disappearing from the desert, and iron manhole covers begin to vanish in the night. Problematically, the raw materials (even when valuable) are still only a small fraction of the value of the infrastructure, meaning replacement costs are high. If commodities were to remain "expensive" in the long run (i.e. worth stealing), how would we re-design our infrastructure systems? (tagged: sustainability economics security infrastructure commodities )
  • Dyson as Sociologist? Death Trains, Values, & Climate Action – Not sure I know quite what to make of Nisbet's take on Dyson. I agree that the catastrophe narrative is dangerous, and much prefer Richard Alley's precautionary point of view, but I really think Dyson is catastrophically wrong on this, and potentially dangerous as a figurehead, whether knowing or unknowing. (tagged: climate science policy propaganda politics )
  • Argentine economics and maker culture – An interesting and personal look at mass production vs. local/handmade goods based on currency strength and protectionist trade barriers. Where labor is cheap, the food and goods are often unique. Where it's expensive, you get mass production. Makes me want to bike S. America. Again. (tagged: economics argentina local money food )
  • China Out to Dominate in Electric Cars (and Why Not GM) – A short chronicle of GM's missteps toward electric vehicles, and China's long view of the same. Honestly, I don't care much who does the dominating, so long as somebody gets this market going. (tagged: cars transportation technology economics china )
  • Oregon’s mileage tax experiment – If you can imagine an America in which vehicle fuel economy increases with time (despite the fact that our national fleet today gets the same mileage as a Ford Model T), then eventually, funding road maintenance with a gas tax becomes a problem. Instead of taxing the fuel, you need to directly tax the road usage – miles driven, normalized by some kind of wear-and-tear factor for a given vehicle. Thus, the idea of a VMT (vehicle miles traveled) tax. Political suicide, you say, but it worked in this (politically insulated) trial in Oregon, and is going ahead gangbusters in the Netherlands and other nations, coupled with GPS enabled congestion charging, and time/location dependent parking fees, it could go a long way toward making personal transportation costs transparent and efficiently priced. (tagged: transportation privacy taxes vmt cars oregon policy )