where MJ = megajoules, L is liter, you get the following:

Diesel: 47 MJ/kg or 34 MJ/L
Gasoline: 44 MJ/kg or 29 MJ/L
Ethanol: 23 MJ/kg or 20 MJ/L
Methanol: 23 MJ/kg or 15 MJ/L
Coal: 24 MJ/kg or 20 MJ/L
Hydrogen Gas @ 691 atmospheres pressure: 120 MJ/kg or 4.7 MJ/L
Compressed Natural Gas @ 197 atmospheres pressure: 53.6 MJ/kg or 10 MJ/L
Lithium-Ion batteries: .72 MJ/kg or 1.9 MJ/L
Wood: 15 MJ/kg
ultracapacitor: .02 MJ/kg

though in actual use you would want to incorporate how quickly these can yield energy (ie power)

the problem with the hydrogen economy right now seems to be not the fuel cells themselves, but the storage of hydrogen (conventionally it’s been pressurized in tanks or absorbed by metal hydrides…).

William Miller was a former provost of Stanford, chairman of Borland software, former CEO of SRI International, and founder of Nanostellar (which he started at age 78!). He mentioned how he has been an investor in 22 startups, 12 of which were complete failures and 3 were ‘home runs’. Nanostellar currently makes materials to reduce the need for precious metals like platinum (which has doubled in price over the past 3 years to over a thousand dollars an ounce) for cars, such as the Passat which contain over $250 worth of the material. I naturally had to ask him about SRI and what he thinks about the fact that it’s one of the only institutions in the U.S. that still conducts research on cold fusion. He said he was woken up in 1990 by a phone call in the middle of the night from his scientists asking if they could make a press conference to release their experimental findings on excess heat generation. He asked if they were any neutrons produced in the reaction. No neutrons, no press conference. He doesn’t deny that there’s something interesting happening there, but maintains that it isn’t fusion.

Werner Vogels, the CTO of Amazon, delivered a talk to the 12 people who showed up for CS 309 class at Stanford a few days ago… he had previously been a researcher at Cornell for 12 years. Seemed a very down-to-earth guy and talked freely about something I had heard of before but never realized the importance of: Amazon’s services to businesses, including the Simple Storage Service and Elastic Compute Cloud. Why is it a big deal? Because startups (and there was one there that backed his claim up) will never have to deal with infrastructure growth pains again… Amazon spent $2 billion building their data centers, and essentially they’re allowing you to rent virtual machines and storage space on-the-fly, meaning you only pay for what you use, and you can instantly scale up from 1 to a few hundred servers… with prices in the tens of cents/hour, it’s very impressive.

Not to mention Amazon Historical Pricing, which is a statistician’s dream (I spent an entire day trying to find sales & pricing data for pharmaceuticals for a statistics paper, only to find them in a yearly publication known as ‘the Red Book’ in the Med School library).

After the talk, I got a chance to ask him why you could sort by average customer rating with book searches, but not DVDs. He said it was possibly just an oversight, and asked me to email him.  Update: This seems to be possible now.

A few months ago I met with my friend Howard Shen who just finished up his MBA @ MIT and asked him about how Amazon’s warehouses work. He explained that there’s no classification system - items are placed randomly on shelves and employees simply scan the item and the item’s location into the database… when an order needs to be filled, you simply look up the number in the database and scan the item to make sure it’s correct. They measure efficiency in terms of how many errors they are between the database and the ‘physical’ reality.

The Segway is neat but too expensive (even Trevor Blackwell’s version)… but two wheels are redundant, no? Problem is unicycles are incredibly hard to balance - it apparently takes months to learn. Though you might be able to use the precession of gyroscopes to stabilize it when not in motion like these guys are doing. Or use a spherical/ball motor, except that they don’t exist outside of research. This is another approach, which I still have to read up on, but looks very neat:

Which gets me into recumbent bicycles, which hold the land-speed record for human-powered vehicles. While this is a regular bike, Olympic cyclist John Howard set a record back in 1985 going at an insane 152 MPH; if that sounds hard, he was helped by the fact that the vehicle he was trailing eliminated essentially all the wind resistence, as seen below (a similar technique is used in professional cycling, allowing the person in front to break the wind for you):

reminds me of the movie “the World’s Fastest Indian.”

So I was reading Kevin Kelly’s excellent book “Out of Control” this summer (apparently actors for the Matrix movie were required to read it before they looked at the movie’s script) when he popped this brainteaser; if a chameleon changes its color to match its surroundings, what does it do when surrounded by mirrors? Settle on a ‘middle value’ or oscillate endlessly between colors? Read the relevant text here.