Hi, In considering new energy technology, one should consider
Compressed Air. It is actually an energy medium, and it can be quite flexible, allowing low tech sources of renewable energy to dovetail with other energy requirements. Compressed air can be stored and moved to where it is required, a movable commodity, and a strong candidate for local use within it's community. The compression of air is independent of precision RPM requirements, and only depends on good seals, standard machine practices
and high pressure air flasks. And yes.... cars are running on compressed air as we speak. And.... they are pollution free vehicles.
This technology may sneek up on us sooner than we think.

Best regards,

Dan

One problem with hydro is that you can't do it everywhere, and I think that in most developed countries, most rivers are already dammed so there just isn't that much more room available for development. I've heard it said (though I may well be wrong) that the Mekong is the one major world river that hasn't been developed heavily for hydroelectric power.

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Why not? It would be expensive to build them, but you'd have a stable, long-run supply of electricity.

Using solar heaters in deserts to generate electricity is a good concept for two reasons. One is that they are relatively environmentally friendly (just mirrors and turbines). And secondly, the steam can be used to make fresh water, which is in demand in desert cities.

I guess a potential drawback is that for Europe, you'd have to have power lines crossing the Mediterranean, and this would make attractive targets for terrorists. There are some security issues.

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Actually the amount of solar energy that falls on the earth in an hour and a half is more than humanity's yearly primary energy use.

The actually makes sense, but the article in New Scientist did state "two weeks." Why is there a discrepancy? Are they measuring something different?

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These numbers sound huge and impossible to achieve, however:

1...In forty years time we'd have to replace all our fossil fuel capacity anyway, so we may as well replace it with low emission generating capacity.

2...If for some odd reason we wanted to supply everyone currently in with world with an average of one kilowatt of wind generated electricity within the next forty years it would cost each person about 3 cents a day. A price that people in the developed world would hardly notice.

I guess they just made a mistake.

One advantage of Solar PV systems is that they can be built at point of use and so reduce the load on transmission infrastructure. Their peak electrical production is also closely matched to peak demand (hot, cloudless summer days). They also have the advantage that retail prices for electricity are much higher than wholesale prices. There is a lot of roof space available for these systems, with the most cost effective locations typically being large flat roofs on factories, warehouses, commercial buildings and so on.

I agree with you 100%. Most recent installations here in Colorado Springs include two areas, one for the PVs (used mostly to power the A/C in the summer), and the other for the solar hot water heating (used mostly for heating in the winter).

On the other hand, I've also seen houses in the area with far better passive heating and cooling designs which require 1/10th the ergs per square foot of living space in either summer or winter. They still have PVs and solar water heating, but they're tiny, and far less costly.

Unfortunately as the New Scientist article quoted before http://www.newscientist.com/gallery/...tching-the-sun points out, near the sea it is rather cloudy, the best sun is well inland. Moving water any distance soon becomes very expensive.

Some people above have said "this is the way we should go". I would agree if it was cheap enough. But it isn't very cheap, so I tend to say "this is the way we may have to go when we discover that it is one of the least bad alternatives". In fact the article indicates that the costs are disturbingly high. In effect it pointed out that doing solar power in an inland area of the Sahara and transmitting it back to Europe is still considerably more expensive than putting up PV collectors in cloudy, northerly European countries. That's really very expensive. Also it's a New Scientist article they are not noted for their accuracy, some contradictory numbers have also been identified by people above.

There has been some discussion of biomass. Biomass is already an important fuel for many people, especially the kind that are rather poor don't use very much fuel. But because of the deforestation they often cause, they tend to be encouraged to try and stop it. And I think that is the appropriate direction of change, because the pollution from their biomass cookers inside their houses also has a very detrimental effect on their health.

Of course we should use agricultural waste as a fuel. And of course people who can locally have sustainable forestry should use it. But globally it doesn't add up to a lot. When you start thinking of taking agricultural land and putting it to the primary use of producing biomass, you compete with land for food. And do the sums for how much you need to make a significant impact, we just don't have so much cultivable land to grow both food and fuel make much difference to the quantities of fuel we use. Algae sounds wonderful: you can grow it at sea, or in water-tanks on non-productive land, and its yields appear to be higher than other kinds of biomass. But it is exceedingly wet, so there is a lot of cost in moving it and dewatering it. So there seem to be some challenging technical problems in devising an economic or practical use for the output, as well as some serious issues with the use of water, etc.

Governments in developed countries talk of reducing their carbon impact to about 20% of peak use. Clearly reducing fuel use has to be part of that.

There are also a few technical issues, like feasibility, maintenance, line losses, etc, which would have to be addressed. I'm not an electrical engineer, but I suspect that power lines across the Mediterranean are not feasible (at least with foreseeable technology), so they'd have to follow a land route. Redundancy would demand a second set of lines, following a significantly different route, so I think the transmission line issue is probably going to make powering Europe from solar farms in the Sahara uneconomical.

Compressed air, per volume, is about 1/150th as energy dense as petrol or diesel.

Furthemore, making compressed air is typically about 14% efficient. That's 86% of the energy coming out of the socket to the compressor being wasted. That energy probably made in a power station by burning stuff.

Meanwhile, a modern diesel engine will be 45+% efficient. So in terms of energy used - your compressed air car is three times WORSE than a modern diesel engine.

As a storage medium, a 'green' solution at present, compressed air is an epic failure.

And they're not pollution free. As with hydrogen cars and electric cars - that energy is STILL being made in a power station somewhere, usually by burning stuff.

Hi, You are thinking "use electricity to turn a motor to turn a compressor".
There are 'other ways'.

That's 'the way' right now.

By all means give us some others currently operating that are 100% non-polluting.

I don't know all that much about it, but apparently the economics look good enough that a bunch of big German companies are willing to invest quite a sum into it. They must have economists who have looked into it and concluded it's a viable idea.

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As above, so below

There is already a link from Spain to Morocco, connecting the European grid to the Morocco/Algeria/Tunisia grids. As electricity is mostly exported from Spain to North Africa any solar thermal plants that are built could first be used to meet local demand. This would be the first step in seeing if the idea of exporting solar electricity to Europe on a large scale is feasible. Of course, a great deal depends on the cost of other alternatives.

Some more bad news for nuclear. The cost estimate for two new reactors in San Antonio has gone up considerably, possibly to $17 billion:

http://www.mysanantonio.com/news/Nuc...ate_rises.html

But at least it is cheaper than some other nuclear projects.

Compressing air requires energy, and the production of that energy is polluting.

Where there's a buck to be had, the market economy will extract every ounce of profit...

And the production of that compressed air is also not very efficient, so making compressed air is actually a very polluting activity. Danscope is yet to suggest an alternative method of making it.

Hi, Wind, solar heated steam, hydro, even low head hydro.
If you consider the value of clean transportation inthe LA area and places such as that which don't clear their atmosphere (it's a bowl), this may be attractive. Depending how you utilize compressed air, it is more effient than you think. The French and the Australians have some interesting designs
already working. Most interesting.
Best regards,

Dan

They're all means of generating electricity. You're then spending that electricity VERY VERY inefficiently to make compressed air. You would be FAR better off using it to make hydrogen for a fuel cell car or charging batteries of some sort.

Hi, These methods I described for you are mechanic sources of torque which can directly produce compressed air. Compressors can be 'ganged'
with succeding pressures feeding the next stage compressor.

Dan

For this reason I suspect the new reactors will be cancelled as they will be able to make more money from another energy source.

One question nobody's been able to answer as of yet, is just how much of the planet we have to leave fallow in order to keep it comfy for humans. That's going to have a huge impact on what types of energy sources we can use. Solar's great, but it takes up a lot of real estate, and makes that land completely unusable for anything else. We can't dam all the rivers to generate electricity (the most efficient way for generating hydro power), and the wind doesn't blow at levels high enough to make it practical for use in many places. (Where I live is pretty much a "dead zone" for wind power.) Tidal power has engineering issues related to it (those will probably solved, for the most part, in the near future), but even so, many of the coastal areas in the world are environmentally fragile and sticking generating gear in them will most likely be prohibited.

I happen to know a power plant engineer who has done consulting work in various parts of the globe, and her reaction to the idea of the US completely ditching coal in the near future is worth quoting:According to this same engineer, there are numerous plants in the northeast US that power companies would love to shut down, but the delays and hassles involved in building a new, more efficient, power plant are such that by the time they get it completed, they can't take the plant off-line they were intended to replace as energy demands have grown so much, that there's no longer enough "slack" in the system.

There is also Jevons Paradox, to consider:We are, within a hundred years or so (possibly less), probably going to max out every possible system for generating electricity, and still find ourselves wanting. Already, there's talks of using giant "kites" to generate power. People have also been researching generating electricity from interstates. In short, if you can think of it, somebody's trying to figure out a way to use it to generate electricity.

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So you're taking the generator off and using a compressor pump instead.

So now - you've built a zero emission generation plant and you're NOT using it to offset carbon based emissions - you're just using the (inefficient) process of compressing air.

I'll say it again, the process of compressing air is inefficient. It is not a long term viable fuel.

From all I've read both on this thread and in other articles, your engineer friend has encapsulated THE main issue. When it comes to energy generation in this country and in many places around the world, we're basically stuck in the proverbial situation of being so busy bailing water of the sinking boat that we don't have enough time to plug the holes. All of the emerging renewable energy generation technologies are great and show a lot of promise for the future, if we can make it that far. Our situation now seems to be that we are coming to the end of a long ride with hydrocarbon energy generation, and there is no viable replacement in sight -- nothing that would allow us to unplug one of those coal burning plants and plug in the clean energy generator without skipping a beat. Perhaps this is what Obama had in mind when he said that the country that develops the next (viable) power source will lead the world's economy. Most likely, he wasn't thinking about wind or hydro or air pressure power, but something really big instead -- something that can replace the coal burning power generation plant. What might THAT power source be? Not nuclear, apparantly, for all the reasons given in this thread.

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The system I suggested is an zero emissions power storage/generation
scheme which dovetails DIRECTLY with automobiles.
Your criticism is kind of like Jake Blues throwing the lighter out the window and saying " Where's the Caddy?" ( or where's the gasoline).
You don't like it?
The solutions to energy in the near future are going to take on different forms from the '67 Camarro people were so fond of. And the attitude of all or nothing is going to cave quickly as new schemes for zero emissions energy
start comming out of the woodwork. The times change. It takes time.

Dan

[QUOTE=danscope;1612710
You don't like it? [/QUOTE]

Nope - I don't.

This is where we're going.

http://www.youtube.com/watch?v=4AUurBnLbJw

As they say - that's the car of tomorrow, because it's just like the car of today.

That certainly looks and feels like a wonderful Car!! And even if they start putting batteries on these things, it still looks like more electric cars in our future. Pretty clean, depending on the total scheme . And pretty simple.

Dan