[grabby]

Take hydrogen cars.

This is supposed to get us off oil.
Hydrgen is made from Natural gas today mostly from what I have read.
maybe 80 percent eficient, and then the HYDROGEN has to be compressed cooled or stored in HIGH energy rich environments (Lithiam aluminum hydride) which also takes energy to amnufacture, and this then needs transport.

so I would say rather than burning LPG in a car directly,
converting it to hydrogen first wastes about half of it.

so even working up to the hydrogen solution with current technology will deplete our reserves of oil even more quickly.

[Ludi]

Human labor is a rather efficient use of energy. I'm having trouble thinking of any "labor-saving device" which takes less energy to manufacture than it would take for the human to do the work themselves, and continue to save energy compared to the energy used by the laboring human. Can you give some examples of these devices?

[brobak]

How about a bike? Not tremendously difficult to make, and its WAY more efficient to ride than to walk 1000 miles.

How about an axe? You gonna chop some wood efficiently without an axe?

[Ludi]

The bike is a good example,maybe, the axe isn't, since the wood could not be chopped without the axe. The fact that the wood could not be chopped doesn't automatically make the axe efficient. One could not get to the moon without a rocket, that doesn't make a rocket an energy-efficient device. Or maybe it does.

How many kilocalories go into making a bike, and how many kilocalories would it take to walk 1000 miles versus biking 1000 miles?

[Ludi]

According to web sources

walking 1 mile takes about 100 kCal
biking 1 mile takes about 35 kCal

now if we had figures for how many kCal go into manufacturing a bike, we'd know whether it truly "saves energy." I suspect it might, over time, but the bike may be one of the very rare "miracle technologies," like the lever.

[brobak]

You dismiss the axe as an example with a really strange analogy. You dont need to go to the moon to survive, but you sure as hell need to work wood. Either to clear land, make fire, build things, etc.

So, its not nearly the same thing. Point being, even though its a simple machine, it does make the job of "working" wood much much more efficient.

And remember, efficiency takes into account a time factor.

Here are some more examples:

Wrecking ball. Its WAY more efficient to dismantle a building this way as opposed to "by hand".

Hang gliders. Jump off a high point, travel (theoretically forever) for the investment of some cloth and aluminium tubing.

A fishing pole. Much easier to sit on a river bank than go swimming after fish all day trying to catch one.

Guns. Another obvious one. Is it more efficient to chase a beast to exhaustion for three days (ala discovery channel ape to man), then haul it back to camp or just pop a cap in its ass right outside camp. Rinse, Repeat.

These things make their particular jobs much more time and energy efficient across the life of the tool. A good gun or fishing rod can last a lifetime. Not much goes wrong with aluminum tubing or for that matter, big ass iron weights. So once the initial investment of energy in the form of manufacturing is done, you have a very long time to recovery that investment in increased efficiency.

[brobak]

As to your walking vs. bike riding example.

How about if we make it a little more real. Lets say you had to ride that bike to the local well to get 5g (40 lbs) of water to bring back to your domicile. Now how does that compare? Carrying 40 lbs on your back or on the back of the bike? Which would you rather do?

The efficiency of the tool has to be looked at in the context of the job that needs to get done.

Thought of another one, jackhammer. Do you wanna try to bust up a sidewalk with your bare hands? Or, even with a hammer and chissel? No thanks. It would take you weeks to do the work that could be done in one afternoon with a jackhammer. Think of the shelter you need, the food, water you'd need to get that much work done.

Its not as cut and dry as you want to make it.

[Ludi]

But are we talking about what we "want" to do, or are we talking about what is "energy saving?"

How much energy goes into making and running the jack hammer?

[brobak]

I get what you are trying to say about the energy invested in the manufacture of the tool, and then how efficient it is when its in use. However, if you want to get certain jobs done, the most efficient way to get them done may be with a relatively inefficient tool. But you simply couldnt get the job done without it, or if you tried, it would be ridiculous (like breaking up sidewalk to plant a garden with your bare hands).

So its kind of a moot point.

I mean, look at the pyramids. They were built (mostly) on the backs of slaves, or human labor.

They took the entire lifetime of the pharaoh to complete. You had to house, feed, and care for those thousands of slaves for decades. How much energy goes into that? Now how about if they had modern "inefficient" tools, like cranes, diamond saws, or anything else they really wanted? You could probably get it done in 1/100th the time. Whats more efficient?


I got another one. Dynamite. Extremely efficient tool for destroying things, or for moving a ton of rock, as in strip mines. Or did youw a want to shovel 100 tons of rock? With you hands?

[bobcousins]

$this->bbcode_second_pass_quote('Ludi', 'B')ut are we talking about what we "want" to do, or are we talking about what is "energy saving?"

How much energy goes into making and running the jack hammer?

[Ludi]

$this->bbcode_second_pass_quote('bobcousins', '')$this->bbcode_second_pass_quote('Ludi', 'B')ut are we talking about what we "want" to do, or are we talking about what is "energy saving?"

How much energy goes into making and running the jack hammer?

[BlueGhost]

Technologies that are made and powered by humans (such as a wooden bike) are probably energy saving. Otherwise what would be the point.
edit> That is energy saving in the context where you'd carry out the task anyway.

Most modern technology is not designed to be energy saving, why bother when we have all this cheap fossil fuel to power it!

Really though I think this is abit of a side issue. The real key to technology is harnessing outside power sources. And we're not going to run out of ourside power source until the sun dies. If you find yourself near a heat gradient you may aswell use it.

Oh and of course you can break up wood without an axe.
With sufficiet body conditioning and a soft wood you can use your bare hands.
Failing that you can use leverage, or fire or a mallet and wedge.
I don't see how energy intensive it is to make a hand axe or a stone axe though!

[Ludi]

I think there may be several "energy saving" devices, such as the wooden bike, wooden and cloth windmill, small sailboat, kayak, lever, archimedes screw, etc.

I didn't expect to see the jackhammer presented as an "energy saving" device.

[BlueGhost]

It's not, why save enery when you have work to be done and external sources of energy far greater than your needs?

This is what annoies me about the whole total powerdown folks.

If you value the survival of your and everyone else's children then we need to use high technology and energy. There's just no alternative.
We will at some point need to survive an asteroid strike.
We will at some point need to survive the suns death.

If you're not interested in the long term survival of the species then why is the shit hitting the fan a problem? It was bound to happen sooner or later and hell we've had one GREAT party.

Edit> I suppose if tshtf is bad because of the human suffering you could propose that we calmly and slowly reduce our population to 0. That way no one would suffer...

[Ludi]

$this->bbcode_second_pass_quote('BlueGhost', '
')
If you value the survival of your and everyone else's children then we need to use high technology and energy. There's just no alternative.
We will at some point need to survive an asteroid strike.
We will at some point need to survive the suns death.

[MonteQuest]

$this->bbcode_second_pass_quote('nero', '')$this->bbcode_second_pass_quote('MonteQuest', 'O')ur machines gain us a short-term utility at the expense of a even greater increase of entropy in the environment.

There are no free lunches.

[nero]

$this->bbcode_second_pass_quote('MonteQuest', '')$this->bbcode_second_pass_quote('', 'A')nd so you again make the mistaken assertion that all labour saving devices must be ultimately self defeating because it required more energy to create the device than it saves when in use?

That's bunk, and if you have an ounce of common sense you'd acknowledge that we can and have invented devices that saved energy and thus decreased the rate of increase in entropy.

[MonteQuest]

$this->bbcode_second_pass_quote('nero', ' ')Glad to hear it. Then you do agree that not all technology is bad?

[MonteQuest]

Some clarity.

Today, it is common to paraphrase the second law: Entropy in a closed system can never decrease.

Entropy here, meaning: unavailable energy.

Entropy is also used today to mean disorganization or disorder. Often, the the second definition of entropy in a dictionary is "a measure of disorder or randomness in a closed system."

The word entropy has also come to be applied to the simple mixing process, say, of two kinds of gasses already at the same temperature. However, if no energy is dissipated, thermodynamic entropy does not exist.

Today, we call this Boltzmann's constant which explains 2nd law at the molecular level.

Logical entropy deals with the logrithmic probability of various states of order. You have to put numbers to it to quantify it. Even though there is an important distinction between the two meanings of entropy, the rule of 2nd law seems to apply nonetheless to the logical kind: entropy in a closed system can never decrease, i.e., physical things never organize themselves.

A broken vase never mends itself. A house not lived in and maintained, deteriorates. A room in disorder never comes to order without an input of energy.

Thus, I believe that this leads to great confusion when discussing entropy. Often one fails to remember the difference and they unintentionally blend together in the discussion.

I will write some more on logical entropy later, so as to clear the air of the confusion.

[nero]

$this->bbcode_second_pass_quote('', 'E')ven though society can effect local reductions in entropy, the general and universal trend of entropy increase easily swamps the anomalous but important efforts of civilized man. Each localized, man-made or machine made entropy decrease is accompanied by an even greater increase in entropy of the surroundings, thereby maintaining the required increase in total entropy.