Simple global warming question

I used to be a skeptic about it, but am somewhat changing my mind.

Anyway, suppose it is a given that carbon dioxide has increased rapidly in the past 100 years or so and is now higher than it’s been in some incredible amount of time.

Is that conclusively linked to “warming”? Has there been alot of warming in the past 50 years that is above the baseline warming? IE has there been warming that is beyond seasonal or random fluctuation? If there is than the carbon dioxide may be causal I suppose.

So how much warming has there been? The whole world is in a slight warming trend since the end of the ice age, right? So how much warming has there been that can’t be explained away? And do the models currently in use that project higher future temps as a result of more CO2 reflect this amount of warming in the past?

Anyway if there is global warming, the only solution is nuclear. That and carbon sequestration, but I think nuclear will be making a big comeback if the ice caps start melting.

We recently have given this subject a good going-over :wink: http://boards.straightdope.com/sdmb/showthread.php?t=263172&highlight=global+warming
On the final point you make - why is nuclear the only option? What about solar, wind, biomass, geothermal…

Solar: too expensive, land intensive, intermittent, available in only some parts of the country. Also manufacturing the silicon cells is not non-polluting. It uses some toxic chemicals. Only captures 10-15% of sun’s energy hitting earth.

Wind: Cost has come down impressively, but is still intermittent and power can’t be shipped easily from say N. Dakota or Montana to Atlanta or NYC. Is also somewhat land intensive, but it’s not as much of a problem inthe MidWest where most of the wind is anyway.

Biomass: Too land intensive to generate energy from. Plants only capture a small amount of energy from the sun, so it’s basically even less efficient than solar.

Geothermal: Works only in some areas.

Basically due to the large amount of power needed, the US needs concentrated energy that can be distrubuted widely. Solar and Biomass are diffuse…they involve taking the sun’s energy over large areas and using it. The power from wind or solar would have to be shipped long distances. Coal, natural gas, oil and uranium are concentrated and you put a plant almost anywhere.

Why the assumption that all power needs to be generated in concentration? Why cannot localised solar power systems add to the mix? (And obvioulsy, I’m recommending as wide a combination as possible, rather than a focus on one source). Capturing 10-15% of the sun’s energy actually produces a hell of a lot of electricity.

And with wind power, you’re contradicting yourself - it’s OK to ship power long distances from concentrated nuclear sources, but not from wind farms? And offshore farms aren’t land intensive.

It should also be noted that solar and other technologies are improving almost monthly. The cells we have today are generations ahead of what we had 10 years ago. Simply covering every rooftop in suburbia could generate massive amounts of electricity at low cost and no land usage.

But Zag, those solar panels also produce heat. I don’t know about current panels, but older ones noticeably elevated the temperature of their surrounding area. Wouldn’t that be a major problem if we layered all of suburbia with them? In turn, couldn’t that lead to even more energy needs as folks tried to use their air conditioners to counterbalance the heat from the panels?

We need a wide mix of electrical sources: solar, wind, hydroelectric, nuclear. It should be a priority of the US federal government to move our nation away from fossil fuel sources.

Hm, I never heard that problem when I researched roof panels for our fraternity 2 or 3 years ago, and I did a lot of poking around. It could well be, I’m not an authority on the subject, and I’ll wait for someone more knowledgeable to come forth.

I can’t find anything online suggesting that heat generation from PV cells is a problem. In any case, if they’re roof mounted, it shouldn’t be too great an issue. And the extra A/C needed will be more than compensated for by the electricity generated.
BTW, I’m intrigued by kennybath’s complaint that solar energy is not 100% non-polluting…I must have missed the meeting where they solved the nuclear waste issue… :wink:

Thanks for link.

This chart was what I was looking for:
http://www.grida.no/climate/ipcc_tar/wg1/figspm-1.htm
Temperatures seem to have gone up rapidly in the past 50 years. The size isn’t that much but the speed is pretty alarming. Maybe it will be counteracted by some kind of natural feedback loop. It’s hard to know until we have more data, I suppose. Of course by then we could be doomed.
Anyway, my point was nuclear could be located close to demand. You can ship power a couple hundred miles, but not a couple thousand as wind need to be.

The sun produces on a clear day at noon about 1000 watts per sq. meter, as I recall. So if you capture 15% of that, you’d capture about 150watts. 6 hours peak production per day equivalent, 365 days per year would be about 300 kwh per year per sq meter. Last year the US used 3.5 trillion kwhs. So thats about 10 billion sq. meters. Plus land for AC converters and everything else.

I think that’s about 1000 miles by 1000 miles of land you’d need if you include everything. It’s in the ballpark of what I was thinking. Are my numbers off somewhere?

Also solar, as I recall, is about $4/ watt, which means that the electricity is about 25c -30c / kwh as opposed to nuclear and coal which is 3-6 c /kwh. Nuclear is often quoted as higher but alot of that is because of delays and re-configuring they had to do inthe 1970s. Once upon a time nuclear was as cheap as coal.

Anyway, so solar needs alot of land. Plus you have to store electricity as the sun only shines sometimes. That storage can raise costs alot. Either you need batteries or pumped storage or conversion to hydrogen. None of those are practical. Hydrogen would just raise costs more as you’d have to convert it back to electricity.

Offshore wind? OK, but siting offshore is going to raise costs. I don’t know how feasible it would be to have it far offshore. Some of these windmills are almost 100 meters tall. Costs per wind is now is 5-8 c / kwh. And again you have problems with intermittency (which means you need backup capacity and since alot of the cost in nuclear (almost all) and coal (probably more than 1/2) is in the actual capital equipment you have to add those capital costs to the wind costs) and storage. As long as wind is a small % of overall power intermittency is not a problem but to heavily rely on wind you’d need alot of backup capacity.
About shipping power…shipping power a couple hundred miles is easier (less losses) than shipping power from S. Dakota to NYC. There isn’t enough wind on the east coast to supply large amounts, I don’t think.

So again, if you need something cheap, that can be located almost anywhere, say 50 miles outside of Atlanta, that can provide baseload power all day, every day, without interruption or intermittency…where are you going to go? Coal, nuclear, gas, etc.

The issue is hardly worth debating. It’s not a case of “do we need to move away from fossil fuels?” Or even if other energy sources are good enough.

We must and will move away from fossil fuels. We have no choice in the matter. They aren’t going to last forever. We must and will make the other sources good enough. We have no choice in the matter. We either like it or lump it.

Nuclear energy is not a solution. We do not have the ability to manage it safely. Past experience has repeatedly shown this. All we’re achieving just now by using it is creating a mess that future generations will have to clear up. Just like global warming, but on a even longer time scale.

I also don’t follow how there could be any doubt whether increased levels of carbon dioxide causing warming. If it doesn’t then our very understanding of the properties of gases and heat is totally flawed. Increased carbon dioxide must cause a greenhouse effect. It’s what CO2 does. All that’s disputed is whether there is anything in the biosphere that will, fortunately for us, counteract this.

My reckoning is that if there is such a thing, it will be just blind chance, not as the result of any global system returning the world to a natural point of balance that also suits us. It’ll just be our luck and there’s nothing to say we should be so lucky.

Couple of thousand? Can you really claim that there’s no sites for wind farms across over half of the US?

Yes. It’s 100Km square.

Current costs of solar, I presume? Massive expansion will immediately lower the costs dramatically.

Wind and solar tend to be intermittent at opposite times, ie good weather v. bad weather, so there’s a degree of balance introduced. And the costs of Scroby Sands are projected at about £1/MW - about a tenth of what you state.

Again, I’d like a cite :slight_smile:

Well that’s one way of looking at it. Nuclear energy produces waste, but it’s a small amount and it’s manageable. Modern reactors burn more of the rods and they can also be reprocessed. Breeder reactors can turn the waste into fuel which can then be burned. You can encase the waste in glass and bury it. Out of sight, out of mind!

My point was that if you rule out nuclear b/c of waste (which is the case now) then you have to rule out coal b/c of mercury, etc. And if the alternative to nuclear is solar (which isn’t realistic, IMO) then you can’t have that b/c of toxic chemicals also. Nothing is completely benign.

What’s 100km square?

Silicon is already produced for the electronics industry. So costs aren’t going to come down as though it’s never been produced before.

Do I claim that wind is infeasible for 1/2 the US? Yes. Wind speeds are low in almost all of the East coast. Unless you build on top of mountains in protected areas.

Cite:

http://www.nrel.gov/wind/wind_map.html

As for the amount of land needed for US electricity, give me a site about 100 sq. km. Or explain how 150 watts per square meter could supply this 3.5 trillion kwh per year. Just stating 100 sq km is ludicrous.

About the wind in Croby sands, whatever that is:

A pound per MW? A large plant is 1000MW. A coal plant would probably cost 1 billion US dollar. Nuclear 2 billion. Gas 500 million. You’re saying a wind plant would cost about $2000 US ? Somehow that doesn’t sound right.

Wind is 5-8 cents per kwh where the wind blows steadily (not east coast). Look it up yourself. If it were 1/10 that it would have already displaced everything else.

This is the attitude I find so bizarre. We already use 1 billion tons of coal per year. That’s 10 million coal cars. vs. 10 coal cars full of uranium. How many tens of thousand of tons of mercury does that put in the air?

Nuclear waste is small and manageable. You may not know how to deal with it, but others do. It may scare you but mercury in the air should scare you more. As far as not knowing how to run the plants safely, again, you’re projecting. Just because you don’t understand it doesn’t mean it can’t be done.

Environmentalists like to take the high ground by saying they’re against pollution. Who isn’t? But there is no energy production that doesn’t produce some. Certainly not solar.

How about the fact that nuclear is just another fossil fuel (the use of “fossil” in terms of fuel is of course more closely related to its derivation from the Latin “fossa” (ditch), implying that the fuel is drawn from the ground, rather than the conjectures that coal and oil derive from decaying organic matter).

You must dig Uranium up, meaning you get it from the ground. There being only so much ground in the world, there can only be so much Uranium. Increased reliance on it only uses it up faster. It also destroys your perceived “manageability” of the waste problem.

Solar, wind and geothermal are the onoly fuels that are self-renewing.

As for your OP, you need to keep the concepts clear:

Global Warming is the phenomenon of rising temperatures. Simple enough. You compare today’s temperatures with yesterdays, the day before’s, and so on back as far as you have records for, and infer anything before that as best you can from geological sampling.

Global warming is a fact. After allowing for dynamic, diurnal, and seasonal fluctuations, global temperatures are on the rise.

the CAUSES of the current global warming are what create the controversy.

The Greenhouse Effect is the trapping of the sun’s heat by atmospheric CO2. This is also a fact, but the questions are whether the current global warming is due to the Greenhouse Effect, and, if so, whether the CO2 causing it is primarily due to human industrial activity. This is something that is not universally accepted, but acceptance of it is on the rise.

About Scroby Sands, the price they quoted is the capital cost. It is 1 million pounds per MW. Or exactly 1,000,000 times what you stated. You missed the small “m”, in there. So it’s about $2M / MW vs. prices I’ve seen in the states of .85M / MW (on land). So it is more expensive. Of course the wind blows harder and the capacity is greater though. But you need to learn the difference between MegaWatt and kilowatthour before you cast stones.

I’m quoting 5-8 cents per KWH which energy. YOu’re quoting power.

Anyway assuming 50% load 1 MW generates 4 billion kwh per year. In exchange you are paying off the interest on the 1 bilion pounds. Plus maintenance. So say 100M pounds per year cost. That comes to .00025 pounds per kwh. Or about 5 cents per kwh US. (assuming 1 pound = 2 us dollars). So yeah, I was pretty far off.

Somehow I get the feeling that you don’t know what you’re talking about?

My units are messed up, a little. That is the output and cost for 1000MW. The price is right though as it cancels out.

No, 100 km square. 100 x 100. And I reached that figure by doing your sums correctly.

Yes, that was my turn to get my sums arse-over-tit.
Are you really telling me that, merely because silicon is already in production, no economies of scale could exist for solar cells?

Yes, you’re right. Uranium isn’t in short supply though. Originally it was thought it was but as the price goes up more and more is found. The amount of energy per kg out of uranium is orders of magnitude greater than coal. So if all was used it would be 1 million times as efficient.

The US uses 10 million train cars full of coal each year. That gives you some idea of the staggering use of energy.