Check out www.pyronsolar.com. They are getting 37.3% efficiency on their solar cells.

Read their calculations for the # of square meters of PV they would need to provide electricity to all of the U.S. Also check out their page on creating hydrogen.

-Andre'

Mr. Leonard comments are indicative of the detachment of many "greens" from reality. The civil engineering feats he nods towards are literally impossible in terms of materials, labour and public support. Many would be simply environmentally devastating if deployed on the necessary scale.

The materials used in photovoltaic cells and wind turbines (e.g. refined silicon, aluminium) are produced through highly energy intensive processes (both of which for a complete life-cycyle release more CO2 than a nuclear plant-and-fuel life-cycle). These are fundamental aspects of these processes related to the material qualities, not something technology is likely to solve. Now imagine a hundred thousand percent increase (if not more) in production.

To create solar or wind power at the levels necessary to replace our hydrocarbon fuels (and apparently since he doesn't mention it) nuclear power, would require industrialisation utterly unprecedented in human history (8000 square kilometers of solar coverage in the site quoted above by "aangel"). The amount of land we would need may sound small in gross terms but is several orders of magnitude greater than any other building project ever. Any one who questioned the morality and reasonableness of the Three Gorges Dam should further scratch their head when Mr. Leonard mentions increased hydro-power in our future. How many more rivers do we want to damn up? Not in my back yard indeed.

Wind power is a particularly questionable approach. It requires a suitable, dispersed rural infrastructure and at present massive hydrocarbon-powered industrial equipment to manage. One must also consider the mental and physiological effects of low frequency vibrations and light flicker on rural inhabitants and wildlife. With a yet un-modelled threat to bats and other avian wildlife added to the mixture. Plus they look terrible in many people's opinion.

"Clean" is a very relative term apparently. Fertilisers, irrigation and fuel to run farm machinery go into raising bio-diesel crops. These bio-fuels then continue to spew out CO2 when burnt. With clean like that who needs dirty?

Mr. Leonard does our environment a grave disservice in failing to mention nuclear energy at all. People's fear of nuclear energy is based largely on ignorance of the science and fear based on extreme events like Chernobyl (imagine bringing up the Bhopal disaster everytime chemical engineering was being discussed). The reality is that we could replace our coal-fired plants (whose fly-ash is more radioactive than any material a nuclear plant is allowed to release) within a decade or two with existing fission reactor technology and with a realistic level of land-use and expenditure. Using electric cars would do away with direct CO2 emissions in the transportation sector and increase the share of electric power (of total energy use) greatly.

He chides peak-oil doomers, but comforts himself with fantasies. I am all in favour of using renewables as a supplementary source of energy, but without a nuclear backbone to world power generation we have no realistic plan for getting off of fossil fuels within our lifetimes. Environmentalists who want to get serious about Big Oil, Global Warming, etc. need to lose their fundamentalist aversion to nuclear energy and look at the hard choices we are facing.

India by the way knows what it is doing. A little renewable, a lot nuclear.

For a depressingly pessimistic situation, check out the Cape Wind fiasco wherein we have environmentalists (and prominent politicos who should know better) railing against a wind farm that would supply much if not all of Cape Cod's energy needs...we in SEMass are getting pillaged by the local electric utility...I've bought bulk electric for my organization and experienced a $7000 savings for 50% more electricity by switching away from the local supplier...and that's just ONE month! Yesterday the regional grid asked for a 13% INCREASE to "encourage" more power plants that are needed to meet regional demand..Fifty miles to the west of Cape Wind, the locals and politicians are railing against an LNG proposal in the heart of the City of Fall River, a lower income "gritty city" Hello?? Our quest for "excellence" is driving out the "good"...and we end up more addicted to the old worn-out solutions that will quite literally change the planet!

It is good to see Mr. Leonard shifting his focus from last week to this. The difficulty of moving from an oil dependant culture to some a clean energy producing society has arrived. We are in the early stages; doubt, dialogue, exploration. I have no doubt the answers are in our "fantasies". That is how humans have solved situations such as this before. My biggest doubt is how do we peons get to convince the elected officials and those who control them that this is the major topic of all our existence? There are no mysteries here. Every new scource has been tried and improved upon. We have plenty of data to go forward.

As far as solar energy goes, John Howe, author of "The End of Fossil Energy", has demonstrated his 10 HP Farmall tractor at the fairs here in Maine to the interest of many farmers. Solar is here.

In calculating the problems of manufacturing new scources some of the new scources can be used in that process reducing the net output of toxic by-products. The improvements will be exponetial. These things can be proven by those who are more familiar than I.

Onward and Upward!

Interesting thoughts regarding how many joules each of those sources of renewable resources has the potential to provide. I'm all for alternative sources of energy, but I have to question a few of the assumptions in the article, really the German article you cite.

First, despite the capacity to generate energy from alternative sources, how will those capacities be limited by competing priorities. For instance, as cool as it looks to have a high-tech Holland full of monster white windmills off in a field somewhere, I hear those things wreak havoc on migratory bird patterns. NPR did an article at some point in the last few years about just how many birds those things kill each year. Additionally, while I live tucked away neatly in suburbia, I hear about complaints that many people have who live near windmill farms have about them. Something about low-frequency noise (again, this was taken from an NPR story in the dim, but not too distant, past).

Second, I wonder if the figure for solar energy is a simple calculation based on the total surface area of the earth being hit by solar power. Recognizing that 3/4 of the earth's surface is covered with water, we might need to trim that solar energy figure by a similar amount - unless, of course, someone wants to create vast reefs of floating solar panels somewhere.

How much, too, of that solar energy figure would require using land that's already used in other ways that may not be compatible with a solar energy farm. Can't put the stuff where people farm. Can't really put the stuff where there's not a reliable source of solar power (anyone ever spend a winter in Detroit?). So, that solar energy figure may be true as far as the total surface area of the planet goes, but my guess is that when you whittle it down to usable space, the figure is substantially less than the one the Germans came up with.

Interestingly, consider where the weather is best suited for solar energy farms. What kinds of places on earth possess those types of environments? Sunny for much of the year. Sparsely populated. Land not all that arable.

Hmmmm, sounds a lot like ... Saudi Arabia!!

Again, I have to wonder: what's the environmental impact of the altermative source of energy?