A Step Farther Out (37 page)

We have the tools. Have we the will?

I can make some claim to having invented the term "energy crisis": in 1970 (in the ante-diluvian period before the Arab boycott) I published an article called "America's Looming Energy Crisis," and that was, to the best of my knowledge, the first use, at least in the popular press, of the phrase. At the time I said we'd best get cracking before the crunch.

We didn't, of course: and things have got worse since then.

The problem with energy is that there are so many misconceptions. "Soft" energies are said to be able to handle the problem: then you work the numbers, and find what wind and tide can really do, and discover there's no chance in that direction. But many still believe in various kinds of magic even so.

Energy is a technical field; you can't avoid getting quantitative if you want to talk about the real world, as opposed to the dream world some "concerned" ecologists live in. (When I was an undergraduate and took a course in ecology the professor sent us off to learn differential equations on the theory that calculus is the appropriate language with which to describe the effects of one process on another; nowadays it's a more than even bet that if I get a letter from someone who signs himself "ecologist" my correspondent will disclaim all knowledge of mathematics, including simple algebra.)

In these chapters I have tried to keep the math to a minimum; but I haven't been able to avoid it entirely, and I don't really apologize for that. Numbers are important. In the field of energy they are
very
important. What's the use of talking about some new process if it can't possibly produce enough energy to save us?

As for example tides. For years the "concerned" types held out tidal energy as a great hope; eventually someone worked out the numbers. It seems that if you built a dam around the entire continental USA (and wouldn't that do wonders for the environment!) and captured all the tidal energy at 100% efficiency, the resulting electricity would just about power the city of Boston.

Wind has the same difficulty: there just isn't enough of it. We all "know" about windy places, but the Department of Energy (DOE; formerly Energy Research Development Agency or ERDA) studies show that most of them are not really windy enough.

Another "soft" energy source is garbage; while fusion is sometimes held out as the hope of the world. These are examined in some detail below. My apologies for the technical details; I can only plead that sometimes the details are vastly important.

If a man told you "The only physics I ever took was Ex-Lax," would you put him in charge of nuclear power policy?

That's not a trick question. The founder of the California People's Lobby once said it, and he was the architect of the Nuclear Shutdown Initiatives.

Alas, nuclear power is seldom discussed rationally. There are those who fear the atom; and others who have made "fusion" an incantation, a magical formula which, when uttered, ends all rational debate about power policies.

In fact, the situation is worse than that: "fusion" is a good word, and fusion scientists are white magicians; "fission" is evil, and its supporters have made pacts with Satan to loose the evil djinn Plutonium onto this world. In these days when our representatives have shunted off primary responsibility for power policy onto the general public—or have abdicated their leadership altogether—it's important that the public deal in physics, not myth.

Now science fiction readers (and I hope, all
my
readers), unlike the Ex-Lax expert, are seldom
proud
of ignorance. Indeed, from the letters I get, and the audience response during my lectures, the opposite is true. The problem is that those who know quite a lot about the energy crisis are often acutely aware of how much they do not know; and thus are conscientious enough not to get into the debates. That's admirable, but it can be disastrous: often only the opinionated and truly ignorant have a voice.

All of which is preparatory to my arguments: I want to plug electron-beam fusion research; but I want your informed support, and since I know, again from my lecture tours, that an awful lot of people don't really understand either fission or fusion, I'm going to start with the basics. My apologies to those who find this discussion elementary. I will try, for the benefit of those whose only physics are Ex-Lax but who don't boast about that, to keep this reasonably simple.

E = mc
²
, saith Einstein; that is, mass (m) can be converted into energy (E). To be precise, energy in ergs equals converted mass, in grams, times the square of the speed of light in centimeters per second. Light-speed (c) is 3xl0
¹⁰
cm/sec, so converting a gram of mass to energy would yield 10
²¹
ergs, something like 100 kilotons, or about 100 times as much energy in all forms as each of you used last year.

The equation says nothing about how that energy comes out. A moment's thought will show you that can be important. If it all comes out as neutrinos it won't do us much good. There's no way to catch them. If it comes out as protons or electrons, we're in good shape: they're charged particles, and we can pass them through a ceramic tube with coils of wire around it to get electricity directly. (That last trick is called magneto-hydro-dynamics, (MHD) and it's a bit more complex than it sounds; but we know how to do it. It only takes energetic charged particles.)

__________

__________

Unfortunately, most nuclear reactions do not produce charged particles. A great deal of nuclear energy appears as neutrons, and we can't catch them in a magnetic basket. What we can do is put something in their way. They get slowed down, or stopped, and their kinetic energy is converted into heat. We extract that heat, use it to boil water, and put the water through turbines. The turbine neither knows nor cares where the heat came from; it's all the same to it whether the heat source was burning coal, fissioning uranium, or fusing hydrogen.

The turbine system is the most efficient thing we've got for turning heat into electricity; but it's not 100% efficient and never will be, nor will anything else, including MHD. Thus let's dispel the first myth about fusion: it
may
be marginally more efficient than either fossil energy or fission, but it will still have waste heat, and will still require cooling systems. No one really knows the effective operating temperatures of
fusion devices—we haven't even got anything that works in a laboratory yet—but if we assume they'll be hotter than either coal or fission, fusion systems will be somewhat more efficient than those we've got; but not all
that
much more so. Known efficiencies for fossil and fission plants, and assumed ones for fission plants, are given in Figure 32.

Fission systems work thusly: a neutron source is brought near an atom that breaks apart. Neutrons are emitted. Other atoms are broken into lighter elements and more neutrons. Some of the additional neutrons are used to breakup even more atoms (chain reaction), others are allowed to bombard useless stuff like uranium-238 and turn it into useful stuff like plutonium-239, and the rest are caught for their heat energy.

Fusion goes the other way. If you squeeze hydrogen atoms together and get them hot enough, they turn into helium. The resulting helium doesn't mass quite as much as the original hydrogen: result, energy. It sounds simple, and it is. This is the reaction that powers the Sun (we think). Unfortunately, we don't know how to do it, and we may never learn. Certainly we haven't even a theoretical clue as to how to bring off stellar fusion; the temperatures and pressures involved are plain beyond us.

So, we go to the next best thing and use deuterium, which we'll call "D." There are two reactions:

D+D—>T+P+3.25 MeV (22,000 kW-hr/gram)  Eq. 1

and

D+D—>
³
He
₂
+n+4 MeV (27,000 kW-hr/gram)  Eq. 2

and I'd better explain what all that means before I lose someone.

First, deuterium is "heavy" hydrogen. Ordinary hydrogen atoms have one proton (p) and one electron (e), and nothing else. D has an additional neutron (n); it could be written as
²
H
₁
where the left superscript is the atomic weight, H is the symbol for hydrogen, and the right subscript is the atomic number.

Tritium, (T), is "superheavy" hydrogen with 2 neutrons, and could be written
³
H
₁
.
By the same token,
³
He
₂
is "light" helium; normal helium is
⁴
He
₂
, and this stuff is missing a neutron.

For reasons we won't worry about here, it's convenient to measure nuclear energies in Millions of electron Volts (MeV), and I've given the textbook figures; for our purposes, though, the kilowatt-hours per gram of material fused is more relevant. For comparison, a regular 100-Watt light bulb will use 876 kW-hr each year if left burning; obviously a 1000-Watt heater uses 1 kW-hr each hour. A kW-hr of electric power costs between 1.2 and 5¢ to generate, and is sold to the consumer for from 2¢ to a dime (although I understand that lawsuits, strikes, and interesting administrative methods have got New Yorkers paying about 20C/kW-hr).

The two reactions shown are equally probable. Both go on at the same time, and there's no known way to favor one over the other.

The tritium and "light" helium can themselves be made to react with more D, as follows:

D+T—>
⁴
He
₂
+n+17.6 MeV (94,000 kW-hr/gram)  Eq. 3

and

D+
³
He
₂
—>
⁴
He
₂
+P+18.3 MeV (98,000 kW-hr/gram)  Eq. 4

and I'm not giving these equations just to show off Look at them a moment.

First, note that tritium. It's radioactive with a half-life of 12 years. We can burn up most of it with the eq. 3 reaction, but we've got to keep it from getting into the atmosphere. It's in the same situation as plutonium: a useful product that we need for power; and it should suffer the same fate as plutonium, "burning" in a nuclear reactor. Until it is "burned" though, it's one of the hazards of the power system, and there's no way to change that. It's also rare: the best way to make tritium is to bombard lithium with neutrons—which makes the lithium supply critical.

Second, note those neutrons. They must be caught if we're to extract their energy. When neutrons hit other atoms, they produce radioactive isotopes. Clever design can minimize the number of truly dangerous radioactive waste products, but can never eliminate them entirely. Thus the fusion industry will need nuclear waste-disposal, and there goes myth Number Two. True: fusion is cleaner than fission power systems; but it is not
that
much cleaner.

Third, the fuel isn't free. We can't use ordinary hydrogen; we have to extract the D from it, and that takes energy; thus, at first, fusion plants will consume more energy than they produce—just as, for the first years of their lives, fission plants haven't produced the energy it took to refine their fuels, or coal plants the energy it took to mine the coal. All will, of course, show a net energy profit after two or three years.

And finally there's the
real
problem: we don't know how to do it. The basic equations for uranium fission were known for a long time before Fermi built his "pile" in the squash court of the University of Chicago, and nature was
very
cooperative anyway: the materials needed for Fermi's experiment were cheap, easily available, and simply fabricated; the instrumentation was standard; and the control system was uncomplicated. Despite the ease with which Fermi demonstrated the feasibility of self-sustained controlled fission (it worked first time), it took twenty years to get usable power from a fission reactor.

There's no reason to believe the engineering of a practical fusion power plant will take less time; and we are not yet to the squash court. We don't
know
that we can do it at all—and we're certainly a long way from running our TV sets on electricity produced by fusing D.
I have never found an expert who believes we will have a working commercial fusion power plant in this century.
The only people who say different are not in the game—and may have very large axes to grind. "Waiting for fusion" is simply not a feasible power policy. There goes the fourth myth. Depressing, isn't it?

Since the above was written there have been some changes. First, the payments for Arab oil have gone out of sight: when your energy policy is to pay out $50 billion a year to the Arabs, you can afford almost
any
alternative.

Secondly, the Soviets have offered cooperation, sending Basov and Rudikov over to show us their results.

Thirdly, in all areas of fusion research there have been some unexpected results; some breakthroughs, other things just going better than expected.