Saul Griffiths' sun-tracking solar systems and intestine-inspired car gas tanks

Extreme maker and MacArthur "Genius" Saul Griffih, of inflatable robots and algorithmically-designed hoodie fame, writes:

(My independent research lab) Otherlab has recently received ARPA-e awards for two great projects in clean energy. ARPA-e is having a vote to have the best projects present at the ARPA-e showcase in a few weeks in Washington DC to get national exposure. We'd like to see both of these projects receive the attention they deserve to enable them to succeed as fast as possible.
You can vote for one, and in fact both, at the links below. Make sure to watch the intestine video beautifully drawn by Nick Dragotta and narrated by Tucker Gilman.
* Safe, dense, high pressure, conformal energy storage for natural gas vehicles
* Low cost high precision heliostats for solar energy.

David Pescovitz is Boing Boing's co-editor/managing partner. He's also a research director at Institute for the Future. On Instagram, he's @pesco.

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http://www.facebook.com/davejenk1ns Dave Jenkins

The laws of thermodynamics and Boyle might have a problem with this scheme. The DOT would _definitely_ have a problem with this idea.
Brainspore

Intestine-inspired car gas tanks? Not looking forward to those, ah, “emissions…”
- Antinous / Moderator
  
  If you live in SF and drive accordingly, I’m pretty sure that your catalytic converter is already pushing out sulfur farts.
  - Brainspore
    
    That’s nothing compared to what would happen with a tank full of Mission burritos.
dioptase

For high pressure cylinders, 1/2 the diameter will mean you only need 1/2 the wall thickness. 1/2 the wall thickness and 1/2 the diameter means 1/4 the weight. But 1/2 the diameter also means 1/4 the volume. So at first blush, it’s a wash. But you’ve now got twice the surface area to volume ratio, increasing potential failure points. And you have half the capacity to tolerate damage.

For instance, 1mm of damage on a 10 mm wall is far less trouble than 1mm of damage on a 1 mm wall.

As for the heliostat proposal, there’s not enough information to evaluate it properly. If all you go by is the use of plastic and the picture, it appears one good storm and you can kiss your solar farm goodbye.
- seanmchugh
  
  The wall thickness is chosen to accommodate a particular pressure. Assuming the pressure stays the same, then wall thickness is independent of diameter. So if one wants to accommodate the same volume of gas, the weight of the container increases proportional to the increase in surface area. Am I missing something?
  - dioptase
    
    The thickness increases proportional to diameter and area increases proportional to diameter. Weight increases with the square of the increase of diameter.
    
    hoop stress = pressure*radius/thickness
    
    So for a constant stress and pressure, the ratio of diameter to thickness is a constant.
    
    reference: http://www.efunda.com/formulae/solid_mechanics/mat_mechanics/pressure_vessel.cfm
    - seanmchugh
      
      Got it. Thanks!
peterkvt80

Why are gas tanks cylindrical? It equalizes the stresses and minimizes surface area. So you need less material to make a stronger tank. Why are intestines the shape that they are? Partly to maximize surface area to absorb nutrients so more material required. The novel tank is going to be much heavier.
- Brainspore
  
  That’s a good point, if anything the stomach is a better analog to a gas tank than the intestines.
BannedinDC

He’s also off a ton on US oil imports. Imports are only 8m barrels per day and have been dropping since 2000 (from a high of 11m). You can blame/thank US shale oil production for that.

source: http://www.eia.gov/dnav/pet/pet_move_impcus_a1_Z00_epc0_im0_mbblpd_m.htm
unclegabby

That makes the tank much more expensive to make, customized for each vehicle, and exposes it more crash zones.
- http://theladyfingers.blogspot.com/ Ladyfingers
  
  My first thought was “that looks a bit too close to the boundaries of the vehicle.”
Colby Gutierrez-Kraybill

Also, methane contributes 75 times more per unit of straight up CO2 added to the atmosphere over a 20 year time-horizon. That may make the broad use of natural gas a wash unless you can leak 75 times less per unit CO2 into the atmosphere.