Re: Art, where's the buzz on nanotech saving America today?

Threeducks wrote:

<snip>

Do you deny that there will one day be a planet earth and the remaining petroleum will either be already burned up or so prohibitively expensive that we will have no choice but to burn something else, whether it be coal or renewable? Surely even if you made the assumption that all of the earth is pure oil, then at our present burn rate any kid who can calculate simple algebra would be able to predict the day when it will all be burned up.


I don't deny that we will eventually run out of oil. However, it takes energy to make ethanol.

That's debatable.

Does it take more energy to make ethanol than
it does gasoline? The power you get out of a gallon of ethanol is less than a gallon of gasoline, so you have to burn more.

On the other hand, how efficiently is it burned? If you require more excess oxygen to burn a litre of gasoline compared with the same amount of ethanol, there's little benefit. After all, some of the energy released in the combustion reaction goes to heating up that excess oxygen as well as the combustion products.

Ethanol is
currently more expensive than gasoline.

That's largely due to availability of supply. What's involved in producing the feedstock for gasoline? One has to first determine where it might be, conduct geophysical tests to locate potential formations, and then actually drill a hole. If there's nothing coming out, one has to try additional methods to coax anything out, if it's there, such as acidizing or fracturing the formation. If one does have a hole that produces, then one has to lay pipe in order to get it to the refinery.

Producing corn or grain, on the other hand, is simply an agricultural operation and certainly takes less time and money.

How are you going to get people
to use something that gives you less performance and less MPG and costs more money?

We have an infinite amount of sun coming down.

Roughly 1000 W/m^2 at ground level.

That isn't going to run
out. Wind isn't going to run out, either. Corn? That takes energy to grow and we may very well run out of that.

Corn or land?

<snip>

We'd better start somewhere and Brazil is ahead of us. I also heard on NPR radio some years ago that, of all places, Kenya generates more percapita electricity by solar cells than anywhere else in the world.


We could just line solar cells up in the desert if we wanted to. Plenty of sun and land out there. Even if the efficiency is low, if you have enough panels you can generate a lot of electricity.

As I mentioned in other posts, a PV installation doesn't just consist of putting a bunch of PV modules somewhere and expecting them to produce power. One as to take into account the location, the availability of insolation (and the ratio of beam to diffuse radiation), and the surrounding landscape. Then there's the issue of whether one wants to track the sun either with respect to azimuth or tilt angle.

Many systems are improperly designed, often resulting in excess power being produced with no load to use it. Also, PV efficiency decreases with temperature but increases with insolation. One should also account for the the load, particularly for those times of peak demand. It might be cheaper to use, say, a diesel genset for load topping.
.

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