photovoltaic economics

I don't have the references anymore unfortunately, but I've read it's something like 3% relative to coal (where CO2 is simply quantitative with fuel burned). Obviously the reactor doesn't release carbon, in and of itself; it's the backend processes, which involve various organic solvents, acids and bases, and all of these require carbon at various points.

Example: nitric acid requires methane, because methane is the cleanest, cheapest source of very pure hydrogen (via the water gas shift reaction). Hydrogen and nitrogen make ammonia, and ammonia, oxygen and water make nitric acid, which makes uranyl nitrate (a compound exactly as neon yellow as its name suggests), a key step in mining, refining and reprocessing uranium (or thorium, for that matter). There are also solvents, ligands, extractions, and so on, used in the processes.

I don't know what actually happens to the solvents used in reprocessing (assuming spent fuel is reprocessed at all, which the US does not; the figure I saw is about a 300% fuel gain for repro, which is certainly worthwhile, but surprisingly not humongous). Presumably, they can be recycled to some extent, but radioactive damage, side reactions and so on guarantee that some is wasted in each batch, which will have to be extracted, disposed of, and resynthesized. And that's ultimately a carbon source.

If we were really committed to a comprehensive clean system, we could of course use nuclear, solar, thermal and electric processes to perform all those steps, even remediating the carbonaceous waste products. That would be quite a stretch, and no one is claiming we need to do that of course. Or would want to, or have the technology to do so -- namely, that we could take CO2 out of the air and, with better efficiency than plants do, turn it into chemical feedstocks for the petrochemical industry. We can do that right now, make fuel from air -- the efficiency is just embarassingly low, kind of a problem!

Tim

I heard the payback time was about 5 years in the UK due to the subsidies. I was opposed to using PV here on ethical grounds, though several neighbours seem unconcerned about me paying them free money; (cunningly this is done by increasing other peoples' electricity bills - not a tax, which would be unpopular.)

However... I got to thinking... our idiot governments have serially messed up energy policy over the last couple of decades, to the point that we no longer have the expertise to build new nuclear power stations, despite it being obviously necessary and desirable. So I intend installing PV. Primarily for energy security, as I reckon we could get blackouts within 2-3 years here. The fact that it will pay for itself within 5 years makes this viable.

Here is another viewpoint(s) I found on a forum I frequent....

the way to go.

whole system is built around.

utilities to make it happen.

rigged elections)

system based on who's

what I see happening.

without any subsidies

parity there will be

boB

ey

I like wind turbines. I pay a few hundred $, per year to get all my electricity from the many nearby wind mills. They are all big 'suckers' on top of the highest hills.

George H.

dies

Well, in that they make more water vapor? And H2O is a bigger green house gas than CO2.

What's the long term choice other than nuclear?

George H.

The

But be careful. Most PV installations are net-metered, and the panels REQUIRE utility power in order to operate. When the power goes out, the PV panels shut down as well. Otherwise, you need expensive transfer switches to enable operation without endangering utility workers.