Well Dave? Am I completely wrong still?

"Since any assessment is heavily dependent on the assumptions made by the authors, it is difficult to objectively predict the consequences of a population size of 520 million on the socio-economic structure of the United States. For instance, if future generations of American citizens are not concerned about ecological compatibility, they could decide to continue to boost agricultural yields per hectare even if they will have at that time a limited amount of arable land available (0.15 ha per capita). As a matter of fact, this is what all European countries are doing at present. Also Japan, China and Egypt, with diminishing supplies of land per capita, are degrading their soils and environments and becoming increasingly dependent for their food security on vanishing fossil energy stocks and imports.

Perhaps it will be possible to feed 520 million U.S. citizen with 0.15 ha of arable land available per capita, but only for a short period of time since such a solution would not be sustainable because of dependency on fossil energy stock depletion and lack of ecological compatibility. Clearly, the costs of that choice would be immense in ecological and energetic terms and would represent a suicidal choice for the future of the country.

As an alternative, it is also plausible that the option of intensifying agricultural production will simply not be there for Americans in 2050. This is a distinct possibility because fossil energy may have become too scarce and expensive, water resources at peril, and soils too seriously degraded to support the required level of agricultural production.

In summary, 520 million Americans represent a number that does not fit with the concepts of sustainability, ecocompatibility, and long-term self-reliance. However, if the U.S. population reaches that size, nothing will be left to be done in 2050. The vital resources that enable agriculture to provide food security will be depleted and there is no way to replenish them. It is only by acting now that the United States can prevent a future disaster."

http://dieoff.org/page55.htm

Once again I see scalability as the possible sticking point. How scalable is the production of the photovoltaic panels?

Well that's kind of irrelevant to my proposal of using hydrogen as a transportation fuel. I used photovoltaic as an example, not a requirement, any source of electricity can be used, including nuclear, geothermal, hydro or wind.

I'm concerned about the scalability of hydrogen production. Right now to the best of my knowledge there are, basically, two alternatives for producing hydrogen: hydrolysis and reforming it from fossil fuels.

I'm assuming you mean electrolysis, and it does solve the problem when you combine it with a renewable energy source that isn't directly suitable for transportation, like solar.

Mount a couple photovoltaic panels on your roof, and they'll spend the whole day producing fuel for your car. Or, your local fueling station could do it, which would probably provide a greater profit margin than what they make off gasoline sales. You could even run it off the grid, and if you use a carbon-neutral source for the grid, you're still getting an environmental benefit.

Like I said, storage is the only real limiting factor in using Hydrogen for transportation.

There is also Hydrogen, it's actually pretty easy to convert a gasoline engine to burn Hydrogen, the difficulty is in the storage.

I'm concerned about the scalability of hydrogen production. Right now to the best of my knowledge there are, basically, two alternatives for producing hydrogen: hydrolysis and reforming it from fossil fuels. The latter doesn't solve the problem and I don't know what the implications of doing the former at a large enough scale to make a difference might be (and I don't think anybody else does, either).

The alternatives we have at hand for vehicle fuels are gasoline, biofuels made from food crops, and biodiesel made from waste.
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The problem is actually somewhat worse. We must power the current U. S. vehicle fleet and the current fleet requires gasoline.

There is also Hydrogen, it's actually pretty easy to convert a gasoline engine to burn Hydrogen, the difficulty is in the storage.

Also, talk about post-Carbon is inaccurate. Carbon isn't the problem, fossil carbon is the problem. Biofuels are all carbon-based, but they're atmospheric-carbon based, not fossil-carbon based, so there is no net increase in atmospheric levels, and thus no net increase in global warming.

In the end, we will build more nuclear reactors to provide electrical power, and will let the biofuels slowly slide into oblivion, in my opinion.

In the end, yes. Biofuels will be beneficial in the near future though, so we shouldn't abandon them just yet. Fission will also only get us so far, we need to figure out how to produce a sustained, exothermic fusion reaction.

A hundred 1% solutions.

If you spread the investments too thin, nobody benefits. We have a limited amount of capital we can invest in alternative solutions, and every solution has a minimum investment requirement. We shouldn't bet the farm on just one, but we can't bet on all of them either.

Productive land is getting scarce too

Completely untrue. We're losing about a million acres of prime farmland per year but it's not due to depletion. It's due to conversion to urban and commercial use.

There continue to be millions of acres of prime farmland that are out of production. Although I oppose ethanol subsidies they've had benefits, too. Land that was out of production has been place in production and rate at which cropland was converted to other purposes has been reduced.

Interesting that we've been sitting on the alternate fuels dream for decades now and no one seems to have created them yet. Perhaps if our scientists weren't so busy chasing global warming propaganda for politically apportioned grant money they might have found the "Eureka" moment by now.

Productive land is getting scarce too, and will become exhausted without fertilizers

If we work to reduce agribusiness and get the artificial chemicals out of the loop, this can be reversed. We now have a great deal of knowledge about sustainable farming, we just have to put it to work on a much larger scale.

That's something of a constant theme for me. BTW, to put some perspective on China's reduction of the gas subsidy (which I posted on at the time), gas still sells for under $2/gallon in China.

Which is near on the price we could have it here, were we not insisting on every state having it's own mandated formulation... one for winter and one for summer.

Sorry, I fail to see the subsidy, there.