Wednesday, April 01, 2009

Going Cold Turkey Ain't Easy

It's one thing to say we should get off of fossil fuels. It's another thing entirely to do it. Mind you, I think we should for any of three or four perfectly good reasons. The brown haze that hangs over Dallas in the morning is one. Impoverishing chumps like Chavez and the al-Saud gang is another. Saving the oil that's left for industrial feed-stock is still another. But we cannot delude ourselves. This is a simply gargantuan undertaking, and it won't happen overnight.

Throughout this post, I'll be referring back to this diagram, which is a detailed breakdown of energy consumption in the United States from 2002:

It's an eyeful, all right. But if you're patient, you can tease some really useful information out of this picture.

First: There's a fairly neat split between the usage of coal, and the usage of oil. When you're talking about coal, you're talking electrical power generation for the most part. And when you're talking about oil, you're talking about transportation for the most part. There's some crossover, but not much. Natural gas is more complicated, being split not quite evenly over electrical, residential, and industrial uses.

Second: Most of the wasted power comes from power losses in electrical distribution, followed closely by energy lost in the transportation sector. Energy wastage in the residential and industrial sectors are small potatoes by comparison.

Now here's the main thing. Let's say that our plan is to eliminate fossil fuels entirely from our energy picture. We'll still use some of them in a nonfuel capacity, as feed stock for making plastics, medicines, and other useful things. But we won't set a match to them and burn them for energy. What this means is that for the residential/commercial sector, the industrial sector, and the transportation sector, we have to supplant the inflow of fossil fuel energy with an equivalent amount of electrical energy.

By the numbers, we delivered 11.9 quads of usable energy to consumers in 2002. The residential/commercial sector consumed 10.7 quads from non-renewable sources. The industrial sector consumed 13.86 quads from non-renewable sources. And the transportation sector consumed 26.5 quads from non-renewable sources. Adding all that up, we will need to deliver 62.96 quads of usable electricity to take up the slack. Note that this is after transmission losses. This means that we have to generate 202.1(!) quads of energy ... all without using fossil fuels. That's 5.29 times more energy than we actually did generate that year. Or more to the point, that's 17.42 times more energy than we realized from non-fossil sources.

That, friends, is a staggering shortfall.

The good news is that this isn't a political problem, or a social problem, but a technical problem. And technical problems almost always have answers. Difficult sometimes, and expensive, but still doable if we want to undertake it. The question is: how?

The obvious first place to look is to see about ways to reduce the amount of "lost" energy. And from the diagram, while there are certainly economies to be found in the residential and industrial sectors, there's not enough to be found to make a huge dent. That's not to say we shouldn't try. But the far larger losses in the electrical and transportation sectors cry out for first attention. Effort spent here will pay far greater dividends.

First, transportation. This, we can actually do something about. Firstly, internal combustion engines are inherently inefficient. This is immediately obvious from the thermal efficiency equation. In your ideal heat engine, you suck energy out of a high-temperature source (Th) and reject it to a low-temperature sink (Tc). You extract work from the flow of energy from source to sink. The maximum efficiency N(th) can be found from:

N(th) = 1 - Tc/Th

where the temperatures are measured in absolute units, either Kelvin or degrees Rankine will do. Internal combustion engines rarely score higher than 0.2 or so. That means only 20% of the energy extracted from the source actually does useful work. The rest is wasted. Electric motors are typically much more efficient, and what's more, we will be using more thermally efficient processes to generate the power in the first place. (Hint: nuclear reactors and fusion reactors have astoundingly high values for Th...) So, at a stroke, by going electric we reduce the energy wasted in the transportation sector. By how much, I don't know for sure. I suspect it's by a fairly substantial amount, though. The other thing to keep in mind about cars is that they spend a lot of their energy simply shoving the air aside. Consider the Aptera for a moment. New, streamlined electric cars designed to slide cleanly through the air instead of batting it aside by brute force don't need to expend as much energy going from place to place. That is quite likely the look of the future.

Second, electrical distribution. This is a more intractable problem. We're pretty much guaranteed to eat a certain amount of loss to Joule heating, which scales as the square of the current I times the resistance R of the power line. This is why power line voltage is so high: that reduces the current, and therefore the power loss. We still lose a lot in transmission. The way around this is a lot more speculative. If we can ever fabricate a superconductor in quantity that will work at ambient temperatures approaching 200 degrees Fahrenheit, this problem goes away. That's a long way off, if indeed we ever get there. My mind keeps coming back to this one, though, because if we pull that off we triple our deliverable energy at a stroke. High cost, but a very high payoff if it works. [Addendum: There's also been some new work on conductive carbon nanotubes, which have a very low resistance compared to conventional wiring, even at ambient temperatures. There's a fair bit of work to be done to make it practical, but that's probably going to happen long before 200-deg-F superconductors come along. An 80% reduction in resistance is certainly nothing to sneeze at.]

For the time being, though, we need to get to work on generating power input. I will take these concepts more or less in order of when I expect them to become major players.

(1) Nuclear power. For all its problems, this is the one we can get started on right now. It already supplies more of our electrical power than natural gas does. It can generate large quantities of base-load power as soon as the plants come on-line. While it entails a degree of risk, those risks can be mitigated. For example, we can task the Navy with producing a common reactor design to use going forward. This design will be sufficiently robust that it can handle any set of reasonable conditions without containment failure. And before you start worrying about terrorists flying planes into them, check this out. Those walls are pretty sturdy. The real bottleneck, though, will be finding enough qualified personnel to run the plants. A massive training program will have to go hand-in-hand with construction. But this option does not require us to do anything we don't already know how to do.

(2) Distributed solar power. I keep reading from several sources about how there's a coming breakthrough in tough, flexible solar panels. Furthermore, they'll be much cheaper. The real breakthrough will be when they're tough enough, flexible enough, and cheap enough to be used routinely as a roofing material. Such things are available now, but they're expensive. As the price comes down, this option will become more popular. There comes a price point when it becomes stupid not to generate your own power. I don't know where that point is, or when it will come, but I'm reasonably confident it's no more than ten years down the road.

(3) Wind farms. Wind power is highly regional, and won't make sense for everyone. But if you get a lot of wind, why not use it? The real question here is reliability: is the source steady enough to rely upon hour-by-hour, day in, day out? In the long run I expect this to be like hydro-power: the regions that have it will use it, and others won't.

(4) Space-Based Solar Power. Much has been written about this elsewhere, and I won't repeat that here. The long pole in this tent is cheap and reliable access to space, which we don't have yet. This is doable if we really want it. For less than we've poured into Iraq, or into the banks, we could probably have built Unit #1, put it in operation, and be well into building Unit #2.

(5) Mr. Fusion! This is the transformational game-changer. Solar power, after all, is fusion power by proxy, given that the Sun is a naturally-occurring gravitational confinement fusion reactor. It's also damn tricky. The joke has been that fusion is the power of the future, and always will be. But there are advances underway on all fronts. The National Ignition Facility just came online. And there's Robert Bussard's outfit, working on the Polywell experiment. Not to mention ITER over in Europe, or the Z-Machine. Magnetic confinement, inertial confinement, inertial electrostatic confinement ... one of them's bound to work, probably more than one. I wouldn't be surprised that it depends on scale. Some methods will lend themselves more naturally to different power scales. This is the holy grail of energy, though, because hydrogen is the most abundant element in the entire Universe, and therefore something we're very unlikely to be short of anytime real soon. There's also less radioactivity to mess with. If fusion tech was available, no one in their right mind would build a fission power plant. (Which is why the Navy is funding the Polywell effort, I expect...)

In summary, getting off of fossil fuels is going to take us a long time, and is going to cost an appreciable amount in R&D. It won't happen quickly. But, hard as it may be, there is no fundamental reason why we can't do it.

We simply have to make the deliberate decision to start moving in that direction.


M. Simon said...

The amount of lost energy in the electrical distribution system can be greatly reduced when carbon nanotube conductors with a conductivity of 5X that of copper become widely available. It will be a while.

As for power generation. This is a good bet:

Bussard's IEC Fusion Technology (Polywell Fusion) Explained

If it works the cost of generating electricity will decline to between 10% and 50% of current costs.

Why hasn't Polywell Fusion been fully funded by the Obama administration?

William Maness said...

In your item #4, you mention the 'long pole' of powersats being cheap access to space. There are a few other poles that compete with that one, but they all fall under the same economic chicken and egg problem. We can't have powersats because we don't have cheap rides to orbit. We don't have cheap rides to orbit, because the traffic volume and repeating loads aren't there. Ditto the thin-film photovoltaic manufacturing conundrum. The answer to this problem is to go to the healthiest balance sheets and leverage them to provide a credit-worthy customer, both for the launch providers, and the PV providers, etc. The utilities, both public and IOUs know how to fund and manage multi-billion dollar generation projects. They have the credit-worthiness to support such activities. Convince them, and the rest follows.

In the interest of complete disclosure...
WilliamManess (at) PowerSat (dot) com

Tim McGaha said...

@M. Simon:

I'd read about the carbon nanotube conductors, but forgot them until you mentioned it. It may take a while, but it'll probably happen before supra-room-temp superconductors. I'll add a note to that effect.

And I've been following Bussard's work for quite some time now. They're getting awfully close. Maybe the next turn of the crank will close the deal. I sure hope so.

As to the question on funding ... well, that's an excellent question. The new Secretary of Energy has spoken positively of Polywell in the past. I'm reserving judgment until I see the budget, though.

@W. Manness:

Yes, it's the old Catch-22 situation. Being an aerospace engineer by education, I tend to be biased towards thinking about the transportation side of the equation, though. Still, even if PVs were free, the $10K/lb cost of getting them up there would still be a killer. That cost has to come down to make it economically feasible.

Burr Deming said...

Good analysis on the opportunities and difficulties. Thank you.