Wednesday, January 24, 2007

Saving not Borrowing

Continuing with the theme that nature runs on current accounts, there are two situations I'd like to cover. One is that nuclear power is really borrowing and the other is that storing energy looks much more promising now.


To follow the first argument, you'll probably want to look at this plot of average binding energy per nucleon as a function of the number of nucleons in an atom. Open it in a new window. You'll see from left to right that the energy rises steeply from hydrogen (H) the lightest element to a peak at iron (Fe) and tails of slowly to uranium (U). It is a beautiful curve with all sorts of fascinating stories to tell, but we just want to look at a simple aspect: you don't get much energy from nuclear energy. True, the scale is in Mega electron volts (MeV) which is high, but what happens in a nuclear chain reaction is that uranium splits producing daughter species at around 120 on the horizontal axis of the plot. So, the energy release comes only from moving left up the slow tail.

Now, when this is done, it makes a mess because the daughter species often end up with too many or too few neutrons to be stable and so they are dangerously radioactive. Some of that mess cleans itself up in under a thousand years, but some of it remains dangerous for hundreds of thousands or millions of years.

We can't build things to last that long; even Hittler's thousand year nightmare did not presume to this. So, we pretty much have to clean up the mess. Now, to clean up the mess we have to remove from or add neutrons to the daughter species to make them stable. Now, here is the problem, for each unstable daughter species you need energies around 8 MeV and so you need a power source as powerful as the nuclear plant to clean up the mess from the nuclear plant.

This means that we have to pay back all of the nuclear power we have ever used and probably more to clean up after ourselves. That means we've borrowed tomorrows energy for today. Nature does not like to work this way, so we're probably on the wrong track using nuclear power. The other end of the curve, where it rises steeply is much more interesting for producing energy. For one thing, it is much harder to produce long lived waste on this end of the curve. This is also how the Sun works.


Usually when we talk about saving energy we mean turning off the lights when they're not being used or insulating a house. This really means avoiding using commoditized energy, not putting energy away for later use. It is true that with ghost energy you could think of this as not burning today what you could burn tomorrow though it really still means borrowing since we still have to clean up the mess. But this is about real energy.

So, by saving I mean storing. There is a little discussion about this further on but here is something that seems very exciting: this flywheel seems as though it might hold a few days of energy, real energy, in a distributed system. To me this means that we can work on current accounts with just the right amount of prudence to allow us to accomodate the intermittancy of renewable energy. This looks very scalable as well, just put them wherever we are participating in real energy. I don't mean to say that this is the only way to store real energy. Sustainable forestry comes to mind as do algae based biofuels. But with this, you don't have to cart it around, which is kind of nice.

Thanks to Ron Backman for the flywheel link.


Anonymous said...

It doesn't matter how bad nuclear is. Coal is worse.

You can scream up and down all you want about lofty ideals such as conservation and saving and frugality, but to do so is to deny reality. The reality is simple. A vote against nuclear is a vote for coal. To think that nuclear energy has nothing to do with fossil fuel energy is naive.

If you are ready to take the blue pill, then go to this article and count up the total number of gigawatts of new coal capacity being planned in the next five years. You will get some number that exceeds 250 gigawatts.

There is no conceivable scenario under which renewable energy sources can procure 250 gigawatts of power over five years. In other words, renewable energy is not even capable of keeping pace with present growth in energy usage, never mind replace our present usage.

I find it amazing that so-called environmentalists can continue to oppose nuclear power. It is almost like they are deliberately ignoring the big white elephant in the room known as fossil fuels. A true environmentalist would advocate immediate nuclear power for the next 10 to 20 years to buy us enough time to properly research renewable energy. Even if we have to "borrow" to use nuclear energy, it's much better than the unavoidable alternative called coal.

Chris Dudley said...

To me, this presents a false choice. We might debate the relative merits of two unacceptable choices, but we are really wasting our breath in doing so.

As to your assertion that there is no conceivable way to produce 250 GW of capacity in five years, lets take just the US and assume 40 GW. A 500 MW solar fabrication plant produces 2.5 GW of capacity is 5 years so you'd need 16 of these. Coal plants usually come in at about a GW and cost about the same to build, so you end up spending about 2.5 times as much on infrastructure for plants going with coal. So, in terms of raising capital, renewables have an advantage over coal. With two 500 MW fabrication plants going into the US this year, one only needs to increase the build rate by a factor of 8 to make new coal plants unneeded. There is an additional factor in that solar power is not always available yet, but niether are coal plants run at their rated power all the time. On the other hand, installed silicon produces about 200 kWh per pound before it needs to be recycled while coal only produces about 1 kWh per pound for a one time use so there are additional substantial savings on the transportation infrastructure side with solar.

Nuclear power has huge difficulties ramping up within five years. You'd need about 13 plants with each one needing a ten year permitting process so they don't even get off the block. This makes nuclear power a particularly poor choice for taking rapid action on global warming.

I would say that the need for research rests mainly in the area of adapting what we know about the Internet and distributed computing to distributed power generation, and in the field short term power storage. These are not roadblocks to the level of deployment you are considering. On the other hand, it makes a great deal of sense to halt the use of nuclear power until we know what to do with the waste. Rather a lot of time and money have already been spent on this with no real progress except to learn that Yucca Mountain won't work.

Anonymous said...

The only reason why nuclear plants need a ten year permitting process is because of the opposition of "environmentalists" like you, so to argue against nuclear power on that basis is circular.

Chris Dudley said...

I feel that the strongest argument against nuclear power is that we don't know what to do with the waste, which could be considered an environmental issue though to me it seems more a question of being responsible and not saddling folks who don't benefit from the power we consume with the problems it creates. To me, the overall physics just does not work out. It does not look energy positive if we are going to be responsible about doing it cleanly.

But, I would say that the reason it is difficult to gain support for nuclear power plants is because they have a poor safety record and people don't want to die horrible deaths owing to a nuclear accident. This is more a public safety issue than an environmental issue.

There are environmental concerns related to the waste, the accidents and future accidents, the mining as well as the centralization of power supply but these don't really come high on the list of issues that lead to low public acceptance of the nuclear power industry.

Envinronmentalist don't wield the power you think they do on this issue. You need to persuade doctors, people who have to work out emergency plans, and property owners that a new plant could work out. NIMBY is your more formidable opponent.

Anonymous said...

By your own admission it would take a production increase of a factor of 8 in order for solar plants to merely keep up with the next five years of growth in coal plants. In case it isn't obvious, keeping up with growth is worthless. Even with zero growth in the number of coal plants, coal is highly damaging.

Meanwhile, nuclear energy right now provides one sixth of the world's electricity. An increase of a factor of 6 would allow nuclear to displace all other electricity sources.

You are only deluding yourself if you think that solar can replace coal. Whether you like it or not, there is a dichotomy between nuclear and coal. In the short term, you do have to choose one or the other (maybe in your fantasy world it is different).

Oh, and by the way, the safety record of coal is thousands, if not millions, of times more appalling than nuclear. It's pretty safe to say that every human being on the planet suffers adverse health effects from coal pollution.

Chris Dudley said...

As I said in the earlier (4/4/07) comment, playing fission against coal is misleading. I think you did not notice that I was meeting a 5 year deadline with solar power. The 16 plants get another twenty years to increase solar capacity before they need to turn to recycling installed capacity. We need about 40 plants to make a sustainable solar only energy system, a rather small number compared to the number of coal and nuclear plants.

As I've said elsewhere, converting to nuclear power completely would exhaust the fuel supply before the plants reached their design lifetimes, a poor investment indeed.

Anonymous said...

The design of your five year plan only makes up for growth in coal usage over the next five years. It does nothing to diminish current coal usage. Even one year of current coal usage inflicts environmental damage comparable to the entire sixty year history of nuclear power.

You also make the rather ridiculous claim that the nuclear fuel supply is exhaustible. However, a simple calculation indicates that uranium alone (not to mention thorium) will last longer than the sun. Literally.

Even if the calculation is off by a factor of a million, we still have five thousand years worth of nuclear fuel. I'll take my chances. It's staggering to think that anyone would choose the certainty of global warming over the uncertainties of nuclear power.

Chris Dudley said...

The five years came from conditions proposed by a commentator. The point is that the plants cover the growth in the required timeframe and then provide 4 times that amount as well as a follow-on.

Breeder reactors are not legal in the US. Extracting uranium from seawater would substantially increase costs for electricity whereas renewables reduce them. This calculation demonstrates that nuclear power is not a viable solution to global warming. There is little uncertainty about nuclear power. It does not work. Thus, serious efforts on global warming need to take a different route.

Anonymous said...

You're going in circles again. The reason breeder reactors are not legal is because of political opposition, so to oppose nuclear plants on that basis is circular.

Your assertion that seawater extraction is expensive indicates one thing. It indicates that you did not read the article I gave. The article says very clearly that the monetary cost of seawater extraction is one to five hundred times less per unit energy than the cost of fossil fuels.

Chris Dudley said...

Thanks for coming back. I think you need to look again at the calculation. It first assumes that breeders will be used before estimating the feasibility of straining seawater for uranium. If you put back the factor of 100, you'll see that you've made uranium as expensive as coal while at the same time needing a much more expensive setup to use it. Those things cost billions.

As we move forward, arranging for energy should be a lower and lower portion of our efforts rather than becoming more complex, difficult and expensive. Renewable energy is headed in the right direction while coal, gas, oil and nuclear power are all headed in the wrong direction. Extraction costs are rising for these depletable resources; the sea water suggestion is absolutely desperate. Technology for renewable power, on the other hand, is only just beginning to take it's scale advantage and it is already cost competitive with coal. That means that the future is looking bright because we'll be spending less effort on energy which is the height of economy! Ask any basking lizard.

Anonymous said...

I will close with the simple remark that you are inaccurate in characterizing the seawater proposal as "desperate." The article that I cited very clearly states that land based supplies of uranium are plentiful and that the sole purpose of the seawater analysis is to prove that even in the most exigent circumstances we have enough uranium to last billions of years.

Chris Dudley said...

The article wouldn't exist if cheap supplies weren't limited. Currently most of the cost of nuclear power is salary and infrastructure rather than fuel cost. If you want to go after sea water or very low quality ores you'll change this and increase costs and this makes nuclear power non-competitive with renewable energy unless subsidies are tilted even further in favor of nuclear power. Before long we'll come to our senses on this.

Anonymous said...

I still don't see where you get these fantastically high estimates of nuclear fuel cost. By your own admission, even with seawater extraction, nuclear fuel costs either 100-500 times less than coal or the same as coal depending on whether breeders are used or not. I have already commented on the wisdom (or lack thereof) of excluding the breeder option.

It is an absolute certainty that, given the political will, we could replace all coal power with nuclear power within five years, and produce nuclear power cost-competitively with coal for thousands of years. No such certainty exists with solar power. Even the simple issue of nighttime solar electricity is a huge never-before-solved problem requiring enormous amounts of untested infrastructure which you have already been kind enough to point out in a different post. I support the idea of researching renewable energy to see if these problems can be overcome, since I agree with you that renewables are headed in the right direction. What I do not support is your insistence (and, worse, your delusion that you are not insisting) on using coal power during the interim while we are researching solar power. Under your long term plan, the only certainty is that we will be dead from global warming before we even find out whether renewable energy is viable.

Chris Dudley said...

I think you place a little too much faith in political will. It is possible to attempt to legislate physical law, but it is not possible to do so successfully. The nuclear industry is moribund. There is insufficient capacity to ramp up in the way you claim. You are suggesting we build about 160 1400 MW plants at about $3 billion each. So, tie up half a trillion dollars with no return for 5 years and hope that an industry that has built no new plants for 20 year can manage to spend that without screwing up? No, you'll have to go much more slowly than that. On the other hand, solar fabrication plants go up much quicker and start seeing a revenue stream right away, so you can get on to the next one, or two. If we're aiming for 40 500 MW plants to sustainably cover our total use including coal, nuclear and hydro then coal gets displaced in ten years, though, as I've said, it will be nuclear plants that get decomissioned first, coal plants will just burn less to begin with.

I do agree with you that storing a few days of energy is important. Many people do this with battery banks now but as I've suggested, alternatives would be a good thing to have. It is not as though there is no present technology though.

So far, I've been considering solar power only because the point is easy to make however wind is cheaper than solar since it has ramped more than solar has so far. A plant that produces wind generators can keep on producing in the same way that a solar fabrication plant can until the point where the generators need to be replaced. Wind has a different availability profile than solar and so may keep coal plants off at night as well.

In all, I think that renewables are a much more interesting an satisfying problem than how to get a bunch of perennial government contractors to find the engineers and such to build 160 nuclear power plants and then run them.