Power Harvesting Brainstorm

May I respectfully refer you to the second law of thermodynamics.

However, the reason there is so much "waste" energy to be harvested is that we are using so much fossil fuel energy to begin with. So if the captured energy allows us to use less energy from fossil fuels, then there is less waste to capture... do you see where this is going?

Ultimately there are two lines. One represents the efficiency with which we use energy. The other is our ability to access stored low entropy. The sun is a long term source and fossil fuels are a short term and nearer by source. The line representing our ability to draw on these local stores that have accumulated over millions of years (from the Sun) eventually intersects with the flow that is available from the Sun. That is the point where the line representing what we use suddenly merges with what we get from the Sun. The suffering we will experience at that point is proportionate to the difference in the slope of these two lines.

Of course a mitigating factor may be things like fusion or more manageable fission reactors but all we are doing is switching to a different form of stored low entropy. We already have available an ideal fission reactor that is far enough away to be fairly safe, the Sun. If we can get by on what it sends us daily then that is ideal.

Here is a picture of a solar farm being installed next to a conventional natural gas plant north of West Palm Beach Florida by Florida Power and Light.

At its peak, the solar plant will be able to generate 75 megawatts. The adjacent gas plant, highlighted by the two smoke stacks in the foreground, reportedly can produce about 3,800 megawatts. Note also that NOTHING will grow under the solar panels (i.e., no carbon will be absorbed), which also means there will be no birds, insects, turtles, field mice...

I think the picture speaks for itself, though...

Of course everything that grows and absorbs carbon rots and releases carbon. It doesn't sequester it but only borrows it for a while.

What I am saying is we need to continue to increase our efficiency so we are able to maintain our desired standard of living while requiring less energy to do so. Is that a bad thing?

And what about the difference in the amount of pollution output by these two sources? You fail to mention that. Yes the solar site borrows no carbon but it doesn't pump tons of it into the atmosphere either. I'm pretty sure that fossil fueled installation is pushing many orders of magnitude of carbon into the environment than the amount that is being temporarily sequestered by the little bit of green growing around said plant.

Now what was your point? I'm not sure I quite got it.

The point is, one needs 50 times more area than shown being used in the photograph to equal the output of that tiny little natural gas power plant. I am not saying the natural gas power plant is the ideal solution, but I am asking that proponents of solar energy be a bit more honest about the environmental impact of solar energy plants on the scale needed to meed our energy demands (note- demands, not requirements)...

50 times? - considering 5.5 hours of sunlight per day the gas plant makes 220 times more power in 24 hours. Our energy requirement is virtually nil - that is what the cavement used. Personally İ am not interested in that and would call my present consumption my requirement. We do need to do better and more if mankind is to survive and progress.

Well there is this bit of news about metamaterial that is promising in terms of improved solar energy capture. Especially interesting because the form of this particular visible light spectrum metamaterial is not a bit difficult to manufacture.

I guess there are no figures yet on the expected yields of this application, but it is a promising technology to reduce the PV area needed and maximize gains.

Sounds interesting but probably at least 10 years away if not more. MİT has an oragami shape they are flogging but that is more of the same. This seems to be more with less area.

Yep. Nice time to be involved in the research. I haven't seen the MIT one, but the designs of metamaterial in general are very interesting and diverse, and the promise of a cost-effective design is good to see.

<...one needs 50 times more area than shown being used in the photograph to equal the output of that tiny little natural gas power plant...>

Like a few deserts, perhaps?

One has to also consider the energy and material needed to produce the solar plant. It is probably much more than 200 times that of the gas plant as the energy source is less dense.

Then, what is the maintenance cost?

I believe that our way out of this mess is not to produce more but to use better.

Look at nature to see examples of using one's wastes to feed another level of life.

If we used the wasted energy from the gas plant to grow food (maybe not useful in Florida but very good in Canada), or to process some material that needs drying (eg wood), then we make a better use of the gas's energy.

Presently, we use the gas to make electricity and use cooling towers to get rid of the surplus heat (complete waste). Then somewhere down the road, this electricity is used by some plant to to produce hot water for their process.

Why not building the plant needing hot water near the electric generator and use their wasted heat? We could have a small industrial park sprouting around these large energy producers to use up the "low" quality heat that cannot be used easily in co-generation.

This is how N.A. can improve its competitiveness and regain a few industrial jobs.

I have read of systems in cities in, I believe, the Netherlands where they are using waste heat to heat other buildings in the neighborhood. This apparently works quite well, so long as the generating facility is reasonably close to the consumer- not a popular arrangement in the United States...

That is why it has to be another industry.

We had a tomato grower build his greenhouse near a paper mill. I think it was in New Brunswick, Canada. He would heat the green houses with the waste heat from the mill. He had a good business. The tomatoes never complained about the mill's smell...

Unfortunately, the mill eventually closed but the principle is viable and productive without subsidies...

You read stories on green sites where they get all excited on this type of thing. Biggest problem is low concentrations of power are normally available and they are not at all economical to capture. 1) Wind turbines on cars - self defeating 2) Piezo electric on roads, dance floors etc - low concentration of power 3) Wind turbines on roofs - exceedingly poor wind power available at that location 4) PV panels on car roofs - low area available and often poor orientation in regards to the sun (or in the shade) 5) Thermal capture of low temp gas/water streams - the technology is not here yet 6) on and on PV power is still horribly expensive if subsidies are not available. A dedicated heat pump is more cost effective for production of domestic hot water than solar thermal at todays costs. Many people should not have a PV setup on their roof as it can be dangerous if not done correctly. İ believe it will be sometime before we see much distributed generation.

A dedicated heat pump is more cost effective for production of domestic hot water than solar thermal at todays costs.
You can build an effective (if you are at a suitable latitude) domestic solar hot water system for a few quid.
The commercial cost is all the labour and extras they put on to jack up the price and absorb the subsidies that the government pays.
Del

Agreed that a solar water heater can be built however probably 95% of the population doesn't have the interest or the time to do so. The one that might be built for a few quid İ am not sure İ want to have on my home for asthetic reasons - didn't spend a fortune on the home to have cheap looking add ons. The subsidies are wild - İ saw on Mariah Wind the price before and after subsidy. As İ remember the cost to the consumer reamined the same while the company profit margin went sky high. Doubt they sell more than a handfull anyway but the company honesty is in serious question.

<Slaps furry head with paw>...you have hit on two of societies big problems.
1. The average person hasn't been taught the skills to make anything properly these days.
2. Too many people are worried by what stuff looks like ie. Fashion...we squander a huge amount of resources in the name of fashion, be it clothes or cars.
We have been suckered into this artifical endless chasing of 'growth', but not even sensible growth which betters ourselves...just a flim flam of sell anything...paint it blue and call it new.
How much of the worlds resources is spent on new mobile phones which will hit the land fill in under 12months?
Del

I have always been fascinated with nature's Rain cycle. It combines many different forms of clean, sustainable, renewable forms of energy into one - call it God's gift to provide man / animal -food to eat, hydo-power energy source, water, distilaltion - all in one . It uses wind energy, change of state (water from liquid to vapor, back to liquid), takes it from ground - high up against gravity effortlessly, moves clouds so that vapour formed over sea, moves to land far away and hills, valleys collect that water and channelises. Rain in concentrated places can wash away cities etc. Hence rain density is lower- so that mankind can enjoy rain- but hills and valleys help to concentrate it - so that we can have dams, collect water, irrigate lands, have hydro pwoer etc. Gravitational force is also used in this cycle. Seasonal efefcts are also built-in. So we can save energy in say water form in dams fro many months- but manu cannot manufacture batteries to store such huge amount of power from solar or wind for months- to beat seasonal effect.

Man is yet to develop a composite energy cycle which can in some way replicate rain cycle. We have wind enrgy or solar energy, nothing combined (after conversion to energy- you can always add).

I have been thinking over ways to tap gravity, magnetic field, anit-gravity (same as archimedes principle to let a body float), change in state (change density of weight(so that it can sink and float or go up against gravity by bouyancy effect etc etc. Tried to put down mathematical equations like mgh for potential energy and similarly for buoyancy force (density of liquid x volume of liquid displaced, but what happens to viscosity effect which will slow down rate of rise of a object sunk below to rise to the top. Archimedes principle does not come to rescue there?) etc etc . But always landed up with huge unimaginable numbers, we cannot handle in say 1 second (power = joules / sec).

I am still looking for such a composite energy generation cycle - like rain

23.4.10

Before attacking "entropy" sources of energy, we must look at harnessing more sustainable and alternate energy sources: WindPower , Solar and Tidal. They are not yet commercially viable/competitive vis a vis technologies we hate with good reason: nuclear and thermal plants.

Here is a snapshot from the Oerlikon website. They claim to be one of the major movers in this technology space:

The upper atmosphere of the Earth receives 174 petawatts (PW) of solar radiation; about 30% is reflected back to space and clouds, oceans and landmasses absorb the rest. The spectrum of solar light at the Earth's surface is mostly spread across the visible and near-infrared ranges with a small part in the near ultraviolet.

The total solar energy absorbed by Earth's atmosphere, oceans and landmasses is approximately 3,850,000 exajoules (EJ) per year. We receive more energy in approx. one hour than the world uses in a year. Photosynthesis captures approximately 3,000 EJ per year in biomass.

The amount of solar energy reaching the surface of the planet in one year is about twice as much as will ever be obtained from all of our non-renewable resources of coal, oil, natural gas, and mined uranium.

Annual solar fluxes & human energy consumption:

Solar 3,850,000 EJ; Wind 2,250 EJ; Biomass 3,000 EJ; Primary energy use (2005) 487 EJ; Electricity (2005) 56.7;

Since the mid-1990s, continuous improvements in solar cell efficiency and PV system reliability (currently with 20-25-year lifetimes) have reduced the average cost of solar electricity by 5% annually.

Solar cell module cost per Wp must cross the magic 1$/Watt line to successfully compete against fossil fuels (without government grants and subsidies).

Oerlikon Solar applies the latest manufacturing technology and economies of scale to enable new, significantly larger production fabs. These are expected to reduce the cost of solar module production by more than half, from $1.3 per watt peak today to $0.7 per watt peak for production lines delivered in 2010. At that cost, PV energy will advance to 'grid parity' with conventional energy sources in Sun Belt regions.

Regards,

Vinay Isloorkar, Pune India

How much of India are you willing to dedicate to solar production? How are you planning on storing the energy once you have captured it? The price of the sloar panel is only a very small part of the overall picture, and by focusing on these sorts of numbers, Oerlikon is misleading the public, raising expectations that are going to be difficult, at best, to meet.

Correct - storage, storage, storage! That is the difficult point. Progress is being made on the collectors but storage is stuck.

There is some progress being made in storage- I don't have a quick reference to it, but I recently read of a very, very large battery being installed in West Texas for capturing energy from lightning- technology that has some potential for other energy systems as well, one would think. But this is still developmental- we don't know yet what the real costs of the system, or maintenance requirements...

Regarding: "storage, storage, storage! That is the difficult point."

and [Post 1] "...these local stores that have accumulated over millions of years (from the Sun)..."

and the O.P.: "They're easy to harvest and convenient, but in the long term — unsustainable" ...

Here's a "freebie": Picking-up the mess from both pulling weeds (by their roots) and weed-whacking around the house, I collected everything in a large black trash bag, and, being 'lazy', dragged it to the back fence-line {closer} instead of to the road.

Finally getting around to the disposal issue (about 3 weeks later), I went to heave it into my wheelbarrow, and found it to be leaking a nasty black mess. The 'goo' looked, smelled, and felt as close to being "used 10-40 motor oil" as anything could be.

Either frown or smile and reject the concept all-you-want ... but you cannot refute the fact that with proper processes in order , the conversion of vegetation into either alcohol or petrol-like products can be accomplished in just weeks (perhaps more than 3, to "get-it-right"), instead of eons and eons.

And, the fact that it is somewhat inefficient NOW (energy INTO the processes for energy OUTPUT of the final product) only means that we haven't perfected the formula and/or the steps, scaling, or biological organisms utilized in the processes.

Without Him, we can do nothing. But WITH Him, ALL things are possible!

--------------G'day to all ~

23.4.10

We will have to shed our skepticism and shed it fast. Coal may be around for sometime , but oil might not last another 2 generations. When the first computer was built, IBM's boss went on record to say that there is maybe a world market for 4 computers. Look what miniaturisation and ICs have done to affordability and penetration of computers. Or look at how mobile telephony has taken off.

Necessity is the mother of invention! Somewhere down the road there will be game changing technologies. I am sure not enough work has been around dopants and catalysts as far as material development goes. Initial breakthroughs on metamaterials at CalTech show promise. Before we bat an eyelid,one of these technologies will become affordable. Ciao circa 2050. Hang in there till then.

Hydro Pumped Storage power plants have been in use around the country for well over 60 years. Fortunately some of them are sited near the hydro and thermal generating sources or consumers. Other pumped storage plants were proposed back in the early 1980's, one comes to mind near Rapid City, SD now in the heart of the wind turbine belt, at the time it was considering transmission line losses too far from the electricity users in Chicago or Denver, and at that time the wind turbine farms did not exist in the surrounding states. Hydro also has high cycle efficiency, can also be used for KVAR production, grid frequency stability and other benefits due to the large rotating WR2.

There are abandoned vertical shaft mines with large underground volumes and above ground areas for reservoirs that can be used for pumped storage.

Pumped-Storage Hydro and underground air storage have the largest capacity (hundreds of MW's per unit installed, sometimes potential thousands at a site) versus batteries, flywheels, and other current developing technologies. For smaller capacities there are energy storage bricks, salts, batteries,...

1) New hydro - not much and not where needed - the greens go nuts when you talk of flooding an area 2) CAES has some hope 3) Large capacity is required - small really is a toy for individuals 4) Flywheels - not much hope for large capacity 5) Batteries - İ haven't read of anything that is not super expensive or still in the dream stage Most storage is out there in the future - Additional practical storage only has CAES as of today

There are many locations for pumped-storage hydro that are as acceptable as the locations for solar or wind or current thermal power cooling systems.

Compressed air storage has far fewer locations available then pumped storage hydro. If a system could be worked out where the underground natural gas storage volumes could have a bladder for Compressed Air then it could be beneficial to both, pumping air into the bladder in winter to exhaust natural gas to consumers and natural gas into the cave in summer to create power from the air.

The beauty of steam is the high "change of state" energy required, if this could be accomplished in large volume and stored, or is there another material (salts, etc.) that have the high heat capacity and that the heat can be recovered and the cycle is efficient ?

This bladder of yours would be rather immense making it impractical - if you have ever studied storing gas you would realize this. Storing gas over seasons is not whatsoever practical - unless it is cryogenic storage and that is rather impractical for several reasons.. Salt caves offer large volumes for air storage in some locations. Hydro storage - again it is a volume problem - not at all like the area required for solar.

The problem with gas storage is that a great part of the compression energy results in hear that is usually lost in the storage tank. This makes it highly inefficient.

Water storage is more efficient IF we can minimize the leaks and evaporation.

Steam storage is a dead end in most case as you must prevent leaks and loss of heat. This is not feasible on a large scale.

Plasma energy storage is even worst as it also tends to "condensate" when loosing thermal energy. The container is too expensive.

Thermal storage in phase change material is promising but it takes so much material. I looked at this for my home but would have been bankrupt by the cost of the salt and containers to operate at useful temperatures. Then, you need pumps, thermal transport fluids....

One is better advised to go to a closed loop geothermal system and use the mass of the earth. This is a practical method presently used. It is economical without subsidies. I used it and am very happy with the energy savings and the simplicity of the system.

You are correct. One can use the ambient atmosphere as energy storage. It is efficient when the temperature range is narrow. You save on the cost of the ground loop.

Air/air heat pumps seem to work well when the winters coldest temperatures are above -10C and summer's peak below 30C. It becomes very difficult (but not impossible) to get an efficiency gain outside of these temperatures.

The narrower temperature changes seen by the geothermal loop improves efficiency at a higher installation cost.

Problem is that we are lazy...cheap, lazy, abundant energy is what we have come to base the global economy on.

When an energy source is found that costs more to aquire energy and energy output is less ROI, people stick with the older cheaper lazy method.

The best ideal power source for the future is Solar, Wind, Hydro, and Geothermal and a global conversion from Fossil Power to Electric Power!!! All 4 above energy sources are the only way of the future by tapping more directly into the suns energy effects on our planet.

While humans may be lazy (or at least many are), I don't think that's the issue. It's a matter of economics. Shouldn't we use the least expensive fuel available?

The problem with solar, wind, etc. is that they are not economically competitive with fossil fuels. As the fossil fuel reserves are depleted, the energy provided by them will increase in cost and at some point the alternative supplies will become economically viable, which should also spurn more investment and research into those area possibly bringing energy costs back down.

"The problem with solar, wind, etc. is that they are" not reliable for 24 hour a day use. They are an intermittent source requiring an overbuild of the system to handle the random generation of solar, wind, etc.

Years ago when there were mini-grids, the electric clock on the wall versus the operator's wristwatch time was what "balanced the load" to maintain 60 Hz. If a power source comes on line to a balanced system, something else (coal or nuclear) must decrease it's output to maintain grid frequency or stability.

The lack of a shock absorber, to consume the random generation of solar, wind, etc. can make the operation of all power plants difficult. Because all thermal power plants want to run at there most efficent "heat rate". The shock absorber is pumped storage hydro usually to temporarily consume the excess power.

The cost difference is a relative number, a few years ago coal power was 2 cents/kwh at night in the upper midwest, daytime power wasn't a lot more. Then solar, wind, etc and even mainitaining hydro were hard to justify.

Why we are having problems is

1. we need electrical energy which is easy to handle and convenient.
2. But storing electrical energy is becoming a problem (problem with battery).

I once again draw your attention my poser on Rain cycle. Nature showed us ways of storing water in dams for time periods longer than seasons.

1. Can we learn from this ?
2. Why use Solar and wind to generate electricity immediately but use it to carry some mass and store it in potential energy.
3. Later we use gravity to convert potential energy to electrical energy.

That is a description of stored hydro - unfortunately locations for such storage are limited and trying to flood any area gets the greens all excited. Stored hydro is in use in many places today. Many parties are working along these lines but the CAES is the only new one being placed in action today that İ know of.

Stored hydro- is again a well known solution and needs large area etc. Let me find a solution to generate say 3 kWs for a single household application - that is exactly how I started trying to replicate rain cycle.

I need not use water. I can use any other material (solid or liquid) and store it in potential energy. Here again - to carry the mass higher - I was trying to see if I could employ Archimedes Principle or some kind of buoyancy effect - which works against gravity. So change of state (like rain water changing state) came into picture. I could not afford heating/ cooling cycle for a single household application. So I tried to look at - say a boat sinks if filled with water, but floats (buoyancy effect) if it displaces water. So can we find solar of wind to change density in some way?

So pl see this as Brain storming- and I have not been able to find a practical solution. All Known solutions are of no use. We need more innovative solutions- think over arin cycle from thsi point of view.

GA.

1- A conventional hydroelectric plant requires about 5 hectares per megawatt (this is derived from a study of proposed hydroelectric facilities in Panama). For Panama, that means 5 hectares of rain forest destroyed.

2- Hydro reservoirs are a recognized source of methane from rotting vegetation (both resulting from the original flooded vegetation, and from vegetation washed into the reservoir in subsequent years).

3- I have personally seen evidence that hydro electric reservoirs interrupt the natural cycling of water, resulting in a significant impact on subterranean aquifer recharge rates.

3- Appropriate sites for hydroelectric sites are getting harder and harder to find in most of the world. While it is possible to build such facilities on relatively flat land, using low head turbines for electrical generation, the lower head available results in a requirement for significantly larger storage areas, which, of course, reduces the significant cost effectiveness of hydro.

4- In parts of the United States (Oregon and Washington states), there is a large environmental movement attempting to remove hydro electric dams. I don't follow their arguments or the developments in this area too closely, but this suggests to me that at least some people find hydro electric facilities environmentally unsustainable...

The movements in OR & WA (İ was born in WA and grew up in OR) are of the really extreme greens - they find nothing environmentaly sustainable except for everyone other than themselves to live in caves. A couple of small dams have been removed but İ doubt anymore will be. Wouldn't it be volume per mW and not area?

What I am concerned with is potable water supply. Destroying trees for whatever reason has a negative impact on the water cycle (of course, this trade off can be justified in some cases, if proper measures are incorporated). Trees slow water run off, keeping aquifers charged, and limiting silting and flooding downstream. Trees also return a lot of water to the atmosphere through transpiration (one can actually see rain clouds forming over forested areas and over forested islands at sea. Ancient explorers would actually sight land from the cloud formations). Forested area is my primary concern. Volume of stored water would be critical for power generation, not aquifer protection.

And forests are beautiful and support diverse life forms.

Oh, yes- as a peripheral benefit, trees also absorb carbon dioxide...

İf you look at the areas where the dams İ have seen in Oregon are there is much more greenry after the dam was constructed than before. That would be central OR, all along the Columbia river up to the Canadian border - very dry desert type of places. There is far more life around the reservoirs than before. The new greenry absorbs CO2 as well - except that there is more of it.

Yes, every area needs to be evaluated from its unique situation. What is right for eastern Oregon or Lake Havisu in Arizona is not appropriate for, say, Panama or Quebec. In India or China, one is looking at another set of issues. There are trade offs for any approach. Covering the Saharan Desert with solar panels would likely have significantly less negative impact than, say, covering large swathes of Florida with the same. What is needed in every case is a rational analysis of what approach results in the least negative impact...No single solution is going to offer a panacea for meeting our energy demands while protecting the environment for our progeny...

Providing 3kW for 24 hours, 72kWH, is the capacity needed. Marine deep cycle batteries should be able to provide this, with considerably more peak capacity.

Look at the battery manufacturers charge-discharge curves, look at solar panel and or wind turbine capacity to recharge the battery's dependent upon your location.

Using ground source heat pumps to supplement for hot water, heating or cooling as possible to reduce load.

The pumped storage using water is typically for large grid systems.

It sounds like you want to fool Mother Nature, maybe by using the heat of the sun to lift the water or the suns light to burn the water to produce heat or ...

You are talking about a significant investment in batteries, which will give you somewhere between 3 and 5 years of service before they have to be replaced, depending on how well you maintain them, the ambient temperature, how fully you maintain the charge, and how deeply you discharge them on each cycle, among other considerations. It is the cost of batteries that normally kill the various alternative power projects I have studied. Trying to save money on batteries by buying cheap batteries is false economy- you wind up having to replace them sooner. At present, a diesel generator is cheaper...

If he buys a diesel gen set to charge the batteries, and the diesel runs most efficient at (lets say) 6000kW so he can charge the batteries and provide power for the application. Then after some 12 hours the diesel can shut down for maintenance, etc and the batteries provide power for the application. There after the diesel cycles based upon battery voltage. Even with solar or wind there would be a need for a backup power source.

I can see you have tonnes of experience in this field. I was involved in starting a manufacturing line for Monocrystaline solar cell panels. So I ma aware of issues related to solar panels & its applications. Things have not changed over decades.

1. Taking specific requirement of India- silicon is imported at high price.
2. We have plenty of unbearable sunshine.
3. We need air-conditioers during day time for domestic(in which case it is not 3 KW but may be 6 to 10 KW).
4. We need not use ACs, but even running air-cooler fans is OK. No need for hot water.
5. Solar heater - fail to my experience- as we have hard water or and the walls of the heat exchanger get salt deposits and in less than 6 months, our electricity bill is back to square one as people put electric heater in built to fool public.
6. Can we keep this brain storm- specifically targeted at domestic application for say Urban or rural India (plenty of sunshine. Higher cost product for Urban and lower for rural). Can we come up with a simple solution (minus expensive batteries).
7. You are absolutely right about subsidies- so US or other countries too are not different from India. It really does not reach the needy. This also brings me to the other point we debated on other blog - behaviour of people / greed is same all over the world !!

I live in Panama. Many people who live in Panama think they need air conditioning because of the high humidity. I do not use air conditioning, and my apartment stays very comfortable, using ceiling fans, open ventilation, and natural shade (well, maybe a couple of times a year, it gets a little uncomfortable during the day...). The key is that the building was constructed before the age of air conditioning. Open ventilation/circulation of air, high ceilings, plenty of shade- all of this was understood in the past. I am sure there are many examples of similar construction in India (a lot of the older colonial buildings I have seen pictures of seem to conform to the ideal tropical configuration).

In drier climates, I have had very good results with Evaporative Coolers. These basically blow air through a saturated mat, which cools and humidifies it. Not good for the wet tropics, though.

Panama also suffers from the high cost of imported goods- without the ability to import raw materials and fabricate things like solar panels. The panels have to be imported finished...

I am of the opinion that the needs of the future can only be met if we can reduce our demand for electricity. Things like LED lighting, building appropriately for the climate, etc. These are only small efforts, but every little bit heips.

Water is going to be a much bigger issue, and getting potable water from currently available supplies is going to be energy-intensive.

One of the most promising things I have seen from an energy perspective is the mini-nuclear power plants, such as being developed by Toshiba of Japan (http://en.wikipedia.org/wiki/Toshiba_4S). This would serve for a fairly large village, I believe, but would not work for the small independent residence...

Many of my perceptions of so-called alternative energy schemes come from personal experience of living on a sail boat for a number of years, where I generated my own power, and used lead-acid batteries for storage. I have experimented with solar, wind, and towed generators. All is possible, but not cheap, and generally one does not get the sort of performance advertised by the promoters.

A very good book for a realistic perspective on alternative energy propositions isDavid MacKay's "Sustainable Energy- Without the Hot Air", available for free download from http://www.withouthotair.com/download.html.

Good architecture could remove/reduce the need for A/C.
After all A/C wasn't available pre-electricity other than by clever design (I don't mean punkah wallah either (sorry if spelling is wrong).
Designing/building with good insulation and natural convection would help a lot..
Del

I don't knosw about Great Britain, but in the US, AC wasn't generally available to the middle classes for home use in the US until some time in the late '50's or early '60's. I believe the first commercial AC's hit the market in the 1930's, but I am not sure of that...

I don't knosw about Great Britain
RAOFPMSL.
We don't actually need A/C in the UK in a domestic setting.
It's needed sometimes in a stupidly designed buildings...like a modern office blocks or factory units.
Del

Let's face it. We don't know precisely what we are going to do in the future. We've pretty much painted ourselves into a corner by living only in the present. We won't be able tell at all what energy sources will be available to us in the future or if energy will even be needed. Potential alternate futures will always be nothing more than that as we limit ourselves with our daily choices. Think about it. As you make that choice in the morning between that double mocha full caffeine latte and that aromatic decaffeinated cinnamon chai tea, you will be limiting your future possibilities. Will you need the quick synaptic energy at 9:30 from the caffeine stimulants for an emergency critical redesign to get the machine up and running or will this quick burn go to waste watching a safety retraining video that you can't correctly answer the dumb quiz because your fingers won't stand still above the keyboard.

This preceding article is a "sneak peek" from the commercial for the new Ronco future visions spectacles. Your's only for $59.95, that's $59.95. We'll send you the spectacles, the spectacle case and even the nose supports. But wait there's more....

harvest some human power, get out of your cars and onto your bicycles; accept a reduction in maximum speed of the remaining cars.

Alter the demand side of this equation and consume less, this can't go on.

Insulate houses, and use less water in them.

People are fashion victims, if you can't beat them join them; make energy saving fashionable. (Remember the ducts in the movie Brazil?)