核电资本成本：货币时间价值与利率影响

[SQUEAKING] [RUSTLING] [CLICKING] PROFESSOR: So we looked at the history of nuclear technology and we learned that it was not optimally selected. It's an artifact of the Cold War that we got where we are. We looked at climate change as a motivation for nuclear. And I made this sweeping statement that without climate change, it probably isn't a motivation for nuclear, just because of the prices. But we found that we can't really quantify the damages from climate change very well.

And so we devised this approach, which is to say we're going to look at cost plus externalities, and then have this free parameter for the social cost of carbon, which we can't define even roughly, because of the phenomenology associated with feedbacks and the way the uncertainties spread out. And we show that after 125 years, scientists have not been able to constrain that number any better over the past century. And indeed, it is itself a time-dependent function that changes as the climate state changes.

So we don't know what it should be, but we know that the optimal level isn't 0, because there at some point the marginal cost of abating CO2 is going to exceed the marginal benefit from that abatement. And so there is some level of non-zero CO2, which is optimal in the system. But this is just like a heuristic that we keep in our head, when we think about looking at different things. We'll use this rough model with the Fried parameter, the social cost of carbon as a free parameter, just to study the phenomenology of the system.

We can't possibly get an exact answer, but we can look at what happens if this SCC is low, the SCC is high. How high does it have to be? How much carbon abatement does a certain SCC drive? And what technology makes it supported under a variety of assumptions? And then you can decide for yourself, what you believe. As far as SCC that gives you the technology output that you want, which is what everyone basically does.

But we will try to ground it in thoughtful assessments that have been done by other entities at some point. OK. So to do this computation, we need to be able to compute the first of these terms, which is the cost of energy. And I want to walk you through how to do that in perhaps a little bit more detail than you've experienced before. And to do that, the first thing we need to do is to review the time value of money.

Now this is the effects of interest rates and so on. And you all have seen this back in elementary school. And you all know that an interest rate causes the balance to go up. And you may even remember all the equations, except do you really know what an interest rate, where it comes from and what does it mean? So I want to try to communicate some philosophical points so that you can have these in your head, so that you can use these numbers in a better-informed way, because it turns out that these numbers, because they appear in the exponent, have an enormous effect on the outcome.

And so you can just select the number that gives you the answer you want, which is what everyone does. And that's bad practice. And if you had a better sense of where these things come from, you might do better at this. So let's just talk about this. Why does the value of money change and why does it matter for nuclear? Well, when you're building projects, they take many years. And so you have to worry about things like inflation.

You also have to pay for it somehow. So you usually borrow money and there's a finance charge, and that goes up as the time goes up. You have to pay interest on that. And another thing that we deal with in building power plants is that we spend lots of money on lots of things over lots of different times. And at the end of the day, we have to have one number, which tells us what it cost. And so we have to find some way of aggregating all of these different streams that happen at different times into a lump sum at a certain time.

And so you probably in your head can imagine how you would do this, but we'll just walk through it real fast. So the first of those was inflation. So why is the value of money change? So it turns out, and I'm not exaggerating here, there's something like 15 different reasons inflation happens. But the basic top ones are shown here. So the first thing is money production. And if you don't know how money is made, I really suggest you go on YouTube and find a video about how money is made, because it's a little weird.

I mean, we could get into it. Basically, it's a process of banks making loans. They create money out of thin air in that process. So go find some video on this, if you're not familiar with the generation of money. I'm not talking about currency. I'm not talking about the US mint printing cash. That's on the balance book. There is so many dollars in circulation in the economy, and it is synthesized by private banks when you take a loan.

It's a really interesting phenomenon. So what happens is, through the process of synthesizing this money via loans, we generate this numerical representation of value in the system. And then there's the real amount of value in the system, which is your labor, and creativity, and your hard work. That's actually generating real economic value. And if these things get out of sync, then the value per unit dollar either goes up or down.

And so that is inflation and deflation. And through monetary policy, we try to keep it the case that inflation always happens. So that the value of the dollar is always going down very slightly. This is to say the amount of money being generated is slightly exceeding the real economic productivity. So that the value per-unit dollar is slowly going down. And someone could probably quickly tell me why that is important.

AUDIENCE: Well, it means you're better off spending money now because it's worth more. PROFESSOR: Yep, and if you don't have that interest, you don't have that motivation-- AUDIENCE: You can just hoard it and not spend it. PROFESSOR: You can hoard it, and then the economy shuts down. So this is all about keeping the economy ticking along. So we have to have this inflationary process. So that's one phenomenon. The second phenomenon that we have is that there's some opportunity costs.

Right? So I could do various things with my money. And if I decide to lend it to you to build your new tokamak startup, I can't do other things with that. And so I demand some payment for giving you my freedom in a way. So that is the opportunity cost. And another parameter that I didn't put here, but there's also a risk factor associated with that, which is to say that if your tokamak startup doesn't work, I might not get my money back.

And so I have to also have some kind of probabilistic and expectation value, some extra factor that says, in expectation I will get all my money back, plus the opportunity charge that I'm taking in. AUDIENCE: It's a really dumb question, but you're mentioning banks, but banks really shy away from funding these kind of facilities because the risk is very high. So what happens if I'm a normal investor, and normally VC because then I'm not really lending money, I'm just investing and many times I'm just getting equity.

PROFESSOR: Yeah but you are lending it in the sense you're getting equity as an instrument that you can then sell, you hope, and get your money back. If you just had equity in perpetuity, that would not be interesting. Yeah. [INTERPOSING VOICES] AUDIENCE: I don't really see the connection with the bank in the sense like you have Commonwealth Fusion Systems, you don't have any banks in their capital. PROFESSOR: That's fine.

But anyone lending money to anyone through any instrument is basically applying the same rule that if I'm going to invest as a VC in your company, I have to consider all the other things I could do with the money, other investments I could make. AUDIENCE: Opportunity cost. PROFESSOR: Opportunity cost plus the risk associated with this particular venture. AUDIENCE: OK.

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