Environmental News

Like hydrogen car manufacturers for instance. Can't get any more dense than that. Maybe we could put them in a sinking wooden ship ... test my theory.

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When I first read the story, I though the Tom Hanks movie, "Cast Away", needs a remake. In this one, he discovers how to make rope and other 'stuff' from thermal plastics and launches a catamaran that easily does 10-15 knots.

Bob Wilson

 

My driftwood and sinking comment was in response to wooden skips sinking.
If the hull completely breaks up, then it all becomes driftwood to wash up some where or sink in time. In most wrecks, the hull doesn't break up in a major fashion, and the weight of the cargo drags the normally buoyant wood down to the sea bed.

 

Don't know why, but this reminded me of this comic.
Saturday Morning Breakfast Cereal - 2010-12-09

 

Any speculations on the next key event in the energy expansion of Earth's continuing evolution?

 

I don't see any reference to nuclear which I think logically follows 'fire'. But that also begs an open question of non-biological renewables, wind, and photovoltaic solar.

Although the growth of nuclear fission has moderated thanks to Fukushima, Chernobyl, and even Three Mile Island, it is still going on, more slowly. Fusion of course is the future (and always will be.)

I'll grant that photovoltaic energy is a variation of solar just by non-biological means. I'll concede it completes with photosynthesis but with a more direct conversion equivalent to fire but without the by-products. So this one may be debatable but wind is something else.

Wind power has more in common with the energy soaring birds use for transportation yet this is not really covered in the earlier epics. Yet ocean currents and wind transport, these have existed for a long time and seem independent of the other energy sources.

Well time to load some Earth, Wind and Fire on the iPhone and work my chores.

Bob Wilson

 

"That difference in salt concentration has the potential to generate enough energy to meet up to 40 percent of global electricity demands."

Does this 40% figure assume that all existing freshwater flows are used? If so, then I doubt it could ever be a globally significant energy source. But it could sure be quite significant to many localities.

This sounds somewhat like the saline equivalent of gravity-powered hydroelectric generation. For a variety of biological and other reasons, we mustn't capture it all, a lot must be left free-flowing. (In some place, we already capture too much hydro.) But if we can somehow agree to a reasonable (and large) portion to be left free-flowing, that can leave a reasonable chunk to try to capture.

 

The largest organisms have the shortest number of conversions from solar to biology energy. We are too young of a species to figure this puzzle out ... and then it will change.

Bob Wilson

 

I see potential in providing power for the desalination plants we are eventually going to need.

Those organisms tend to spend all their time simply eating. Lions have free time to watch their next meal get fat. Free time let early homonids exercise their brains more.

 

I'm not seeing that. If the locations are close, it would make more sense to divert and capture the fresh water flows before they mix with the salt water, avoiding two lossy and costly conversion processes.

If the paired salination-desalination locations are far apart, the energy transport costs will be substantial. It would be better to match them up with local energy loads and sources.

 

Most desalination plants make use of reverse osmosis to produce fresh water from seawater. The process results in a stream of concentrated brine in addition to fresh water. Even if the plant used a more exotic process like solar based distillation, there is going to be the salt that was taken out to make the fresh water that needs to be addressed, and pumping brine is more efficient than shoveling salt.

Right now the waste brine gets dumped back into the sea. The salt gradient isn't as great between the brine and seawater as between the seawater and fresh, but a gradient is there. I can't say how efficient using that gradient is for producing electricity, perhaps the short distance in which the brine and seawater mix makes the process more efficient, but it will produce something to offset the electric used in the desalination process.

 

It would seem that reducing the initial concentration of that RO brine should be more efficient than would trying to use it for electric production.

This should be like trying to use the heat from the coils of a refrigerator to drive electric generation. It is generally more efficient to improve the initial refrigeration system to shed that waste heat at a lower delta-T in the first place.