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Comment: Re:Question on EROEI (Score 4, Insightful) 256

EROI still matters as that basically tells energy investors where they will get the biggest return for their money.

The trick is that the EROI for fossil fuels is decreasing as all the easy reserves have been tapped. We're mucking around with high tech dynamically positioned rigs for deep water drilling, oil sands, etc... that require more energy and effort to obtain. The EROI for coal has been depressed artificially due to environmental regulations and CO2 rules, but there are still ample reserves. The EROI for wind and solar should be relatively flat, even rising slightly if the technologies improve.

At some point the fossil fuel EROIs will fall below the EROIs for renewables. It's just a matter of when. Whether you invest in renewables now or later really depends on your perception of the outlook for these energy sources.

The thing to keep in mind is, low EROIs mean low net power production. An EROI of 1.01 is energetically feasible, but it means you are only getting a net surplus of 0.01 units of energy for your 1 unit of effort. That 0.01 is what you get to power your society with. If you are using a technology with an EROI of 1.01, it means you will need a LOT of that technology to power society. You will actually need nearly 2X a LOT of that technology as you need nearly the same amount of power to simply make the technology.

Comment: Re:Bridges Are Not Static Structures! (Score 2) 36

by Irate Engineer (#49722909) Attached to: Using Satellites To Monitor Bridge Safety

Maybe, but this won't catch a lot of failures caused by corrosion or fatigue cracking, or under-designed structures that are built with excessive static deflections from the get go. Many times the first excessive deflection is the one that sends the bridge into the river. Even if this worked as advertised, it does not replace visual inspection for defects.

Look at the I-35W bridge failure in Minnesota as a case in point. Sadly, this bridge *had* been inspected visually, numerous times, and was found to be structurally deficient by design, with cracking, corrosion, and bowed gusset plates all seen and photographically recorded prior to the collapse. It was cheaper to simply schedule periodic inspections, but the inspections never triggered the required (and costly) corrections that were needed. A peak load due to construction materials and gridlocked traffic was the last straw. All the GPS and satellites in the world can't cure human stupidity.

Comment: Bridges Are Not Static Structures! (Score 2, Informative) 36

by Irate Engineer (#49722569) Attached to: Using Satellites To Monitor Bridge Safety

The author of TFA doesn't have a clue. This idea is useless as bridges, particularly suspension bridges, deflect by much more than 1 cm under traffic and wind loads.

Here is a time lapse video of the Manhattan bridge to illustrate normal deflections:

https://www.youtube.com/watch?v=DgXveBf_l6k

Comment: Crack Filling = Hiding Critical Flaws? (Score 3, Insightful) 94

by Irate Engineer (#49699807) Attached to: Biologists Create Self-Healing Concrete

If the concrete fills it's own cracks automagically, two questions spring to mind: 1) Will the crack-filling material have the same load bearing properties or (as I suspect) it will be much weaker at those spots, and 2) will the filled cracks disguise the facts that the object may be under a load that was not anticipated by the designer (tensile or bending loads vs. compressive loads)?

Reinforced concrete is often used in bending and tensile load applications in architecture, and if the reinforcing is not stiff enough cracks often will appear on the surface. They are unsightly, but if the reinforcing is taking the load (as it should) these are not structural deficiencies. But for complex architectural domes and shells, the presence and size of these cracks is something that needs to be monitored.

If the concrete is used in a container and it cracks, we may actually want to see the crack as that is a warning that something is being loaded in an unanticipated way. Hiding it with a self-filling mechanism may not be desirable.

Comment: Re:Snowden... (Score 1) 142

by Irate Engineer (#49687127) Attached to: House Votes To End Spy Agencies' Bulk Collection of Phone Data

No, one can be pardoned even before being indicted. See Ford's pardon of Nixon for an example. The presidential pardon is a pretty powerful tool, but the president can't wield it too freely as there is great potential for political backlash against the party.

If a Republican gets the White House in 2016 (or even if they don't), I hope Obama mans up and pardons Snowden and Manning and others who blew the whistle on this. It would be one of the few things he could do to redeem his half-assed presidency IMO, but I am not holding my breath.

Comment: If A Spy Agency Stops Collecting Data on You... (Score 2) 142

by Irate Engineer (#49687089) Attached to: House Votes To End Spy Agencies' Bulk Collection of Phone Data

If a spy agency stops collecting data on you...how do you actually know?

Strangely enough, having a bunch of politicians say "We voted against it, so we won't collect data on you, promise!" really doesn't seem too compelling to me.

I think I will be keeping my tinfoil hat on with chin strap secured, thank you very much.

Factorials were someone's attempt to make math LOOK exciting.

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