Monday, October 27, 2008

We Won't Get There from Here

AOG and I have been debating the feasibility of space travel, first to the stars, most recently closer to home.

Other than the "Mt Everest" on-account-of-it's-there argument, making the effort requires a payoff exceeding the opportunity costs. In other words, there must be resources or processes that are less expensively obtained in space than here on earth. The most obvious, if not only example, is orbital power stations transmitting solar energy as microwaves to Earth, then converting the microwave energy into electrical energy.

The pro-arguments are powerful: sunlight 24/7, essentially no environmental impact, and no fuel costs once installed.

The counter-arguments focus largely on lift costs to geo-synchronous orbit. Absent assumptions so optimistic as to make Pollyanna blush, moving sufficient mass for an orbital power station will be many times the cost of the station itself.

However, granting Pollyanna her due requires making assumptions about what is technologically possible. In fairness, expanding technological possibility must also be granted to life here on Earth:
SOLAR power should be a cheap and simple way of making electricity, but like any technology the practicalities tend to get in the way. Even if the sun does come out the panels may not face in the right direction. Then there is the cost, which can exceed $40,000 for a household system—more than half of which is accounted for by installation.

...

[Several firms are using new materials] to produce the photovoltaic effect and building them in extremely thin layers, almost like printing on paper. As these films use less material they are cheaper to produce, not least because they can be deposited on bases like metal, glass and plastic.
The downside of these new materials is that they are less efficient than existing silicon-based photovoltaic materials.

However, efficiency is not everything. Not only are the new materials cheaper, they are also flexible. This, in turn, mitigates many of the disadvantages of terrestrial solar power, by providing the ability:
... to coat glass tubes with [the new photovoltaic materials] and encase them in another glass tube with sealed ends. They look a bit like fluorescent-lighting tubes. Forty of these tubes are then assembled into a single panel. Using tubes instead of flat panels makes it possible to capture sunlight, including diffuse light, from any direction—even if it is reflected up from a roof. And whereas traditional solar panels have to be tilted and carefully positioned so as not to shade nearby panels, tubular ones can be laid flat over the entire roof. Being lightweight and open they are also less prone to being blown away. This makes them easier and faster to fit. The cost of installation, reckons the company, should be about half that of conventional panels.
The company pioneering this approach is focusing first on the flat rooftops of commercial buildings:
Chris Gronet, [Solyndra's] chief executive, says that with some 30 billion square feet of large flat roofs in the United States alone, tubular solar cells could generate 150 gigawatts of electricity. That would be enough to power almost 16m homes.
What if the installed cost of these panels turns out to be $20,000 for a household roof top installation? Assuming a $200,000 house with zero down, financed at 7% fixed for thirty years. The monthly payment will be $1330.

Now, roll a $20,000 solar panel installation onto the mortgage. The resulting payment will be $130 more per month. Roughly speaking, about the same as that house's monthly electric bill.

On many days in the lower 48, such an installation could very well end up generating more power than the house consumes during the day. That excess power can be sold back to the utility, which could then "store" it for use at night. Alternatively, battery powered vehicles capable of spanning a typical American commute look likely to appear in the not too distant future. The roof panels could be used to recharge those batteries, thereby eliminating the fuel cost of commuting.

Of course, the batteries need not be confined to the car. No reason they can't be part of the house, charged by the solar panels during the day then supplying the same house's electrical needs at night.

While I do not want to make assumptions sufficiently hopeful to make Pollyanna a hardened skeptic by comparison, the efficiency of household devices is headed in the right direction to make a energy self-sufficient house possible. For example, LED light fixtures are becoming, at 1/3 to 1/5 the power consumption of incandescent bulbs, economically feasible, even before taking into account the far lower load their operation would impose on air conditioners.

Who knows whether these developments will pan out. I can well remember the hoohah surrounding the invention of high-temperature superconductors, and the funereal silence that has prevailed on that subject ever since.

However, the possibilities are far closer to eventuality than anything proposed to yield tolerable lift costs into LEO, never mind geosynchronous orbit.

And, if just two things happen -- viable rooftop solar panels and cost effective batteries -- the most obvious raison d'être for space presence has just been brought crashing to earth.

9 Comments:

Blogger Susan's Husband said...

The big consumer of electrical power is industry, not households directly, so it is not clear to me that this will make the difference.

On the other hand, technological progress happens in other places as well.

P.S. I was thinking that if an orbital elevator costs $100B to construct, that's quite feasible, given the $24B spent (in older dollars) for the Apollo project which had much less scope for economic growth. And if you're not careful, I will bring up the military aspects of space travel (if you own the orbitals, you own the planet).

October 28, 2008 6:25 AM  
Blogger Hey Skipper said...

... it is not clear to me that this will make the difference.

Presuming battery technology progresses far enough to make electric cars with 100 mile range practical.

Which means that households, in addition to supplying their own electrical power, would also supply the energy required for at least 85% of their driving.

Sounds like making a pretty big difference to me.

And if you're not careful, I will bring up the military aspects of space travel (if you own the orbitals, you own the planet).

What you will first need to do is explain how orbitals (whatever they are) can be owned.

Then, get from there to owning the planet.

Presuming that, though, you are left with the problem of persistence.

When the Chinese blew up one of their own satellites, the demonstrated two things.

First, and least significant, they showed they can attack objects in LEO.

More importantly, though, they demonstrated space denial.

How many rockets would have to be launched, with no greater goal than blowing themselves up in orbit, in order to, say, require evacuating the ISS because the debris impact risk became untenably high?

For a very long time.

October 29, 2008 11:08 AM  
Blogger Mike Beversluis said...

I can't see anyone going into space for power generation, not if the PV Moore's Law holds.

October 29, 2008 6:26 PM  
Blogger Susan's Husband said...

Mike;

Skipper and I argued about that inconclusively, my point being that historically, increases in efficiency lead to large increases in absolute energy consumption. Skipper claims we've reached a tipping point after which that rule no longer holds.

Skipper;

It's the high ground. If you have a large orbital presence, then you can drop the equivalent of nuclear JDAMs anywhere on the planet anytime you want. Someone launches an anti-satellite weapon, you vaporize the launch site. You might as well ask why machines in the air would matter to ground combat.

October 29, 2008 8:09 PM  
Blogger Hey Skipper said...

It's the high ground. If you have a large orbital presence, then you can drop the equivalent of nuclear JDAMs anywhere on the planet anytime you want.

Two questions.

First, how large an orbital presence would you need in order to hit any spot on earth within 12 hours? Okay, limit the problem a bit: any spot on earth within 60 degrees of the equator. Roughly speaking.

Second.

Why do you need orbital presence to do this? Any particular reason ballistic missiles can't do the job faster and cheaper?

Skipper and I argued about that inconclusively, my point being that historically, increases in efficiency lead to large increases in absolute energy consumption.

I read just yesterday (sorry, can't find the reference) that US energy consumption dropped 1% between 2003 and 2005.

October 30, 2008 11:05 AM  
Blogger Susan's Husband said...

"how large an orbital presence would you need in order to hit any spot on earth within 12 hours?"

One satellite can hit anywhere on its orbital path in 2 hours. So, probably 12 or so satellites.

"Why do you need orbital presence to do this? Any particular reason ballistic missiles can't do the job faster and cheaper?"

Why do we have an air force when we have cruise missiles?

But more specifically, among other reasons, is that an orbital presence makes calibration of the response fine grained. If you use ballistic missiles you pre-select the response level and then hope it's appropriate for the situation.

Plus, if you own the orbitals then you can stop other people from using orbital weapons or ballistic missiles, i.e. they can't shoot back. That's no small advantage.

October 30, 2008 12:18 PM  
Blogger Hey Skipper said...

One satellite can hit anywhere on its orbital path in 2 hours. So, probably 12 or so satellites.

That doesn't sound right. Take the most limited case, that a weapon launched from a satellite can only fall along the ground track of the satellite. In that case, then it would take the earth's diameter divided by the weapon's damage diameter. That is a bloody lot of satellites, if the latency is going to be two hours, fewer if one is willing to wait until the orbital period and the earth's rotation align to put the target under the satellite.

That number goes down as the cross track range increases. Unfortunately, the only way to get cross track range is to add mass in the form of fuel and motor. Which, in turn makes the satellites far more expensive.

I don't know what the real number is, but I'll bet it is much more than 12.

But more specifically, among other reasons, is that an orbital presence makes calibration of the response fine grained. If you use ballistic missiles you pre-select the response level and then hope it's appropriate for the situation.

Why?

With an offensive satellite, the response has been irrevocably pre-selected to the weapon's characteristics when it was launched -- it is the very model of inflexibility.

In contrast, a ballistic missile, just like an airplane (or cruise missile) can have its weapons load adjusted based upon target and situation, individually targeted, with TOT less than an hour after launch.

Plus, if you own the orbitals ...

I am still in the dark as to how one "owns" orbitals.

October 30, 2008 1:58 PM  
Blogger Susan's Husband said...

You can use the atmosphere to get a lot of distance from the ground track. Plus, if you take your original 12 hour limit, then you can drift a long way with a rather small orbital adjustment.

As for flexibility, what you orbit is a collection of smaller weapons, dozens or hundreds per satellite. Then you can drop one, five, 20, whatever, over a small or large area. The cost per submunition is constant, unlike the cost of a ballistic missile to deliver it.

October 30, 2008 4:56 PM  
Blogger Hey Skipper said...

You can use the atmosphere to get a lot of distance from the ground track.

No, you can use it to get a little bit of distance. The re-entry phase would last, at most, 2 minutes. Even if it could somehow instantly obtain a lateral velocity of 600 knots, that only spreads the impact zone by twenty miles either way.

Plus, if you take your original 12 hour limit, then you can drift a long way with a rather small orbital adjustment.

True, but the more constrained that 12 hour limit is -- and I based upon the time it would take an airplane to get from the US to the furthest point on Earth -- the more satellites you need.

For a response time of one hour, easily attainable by an ICBM, the number gets out of control.

The cost per submunition is constant, unlike the cost of a ballistic missile to deliver it.

The costs of both are constant.

However, the more constrained the response time, the more expensive an orbital system becomes, as well as the wastage. For ICBMs you buy as many as you think you will need; for orbiting weapons, you have to buy as many as you need to obtain the required response time, which, for a one hour response time, is going to bear no relationship to threat-driven requirements.

Of course, if you have to use some sort of rocket to get the weapons into space in the first place, then their cost advantage disappears, and becomes a positive disadvantage if response time is important.

Finally, there is no reason an ICBM couldn't deliver precisely the same weapons as an orbital platform.

Sure, delivering weapons from space provides an excellent tactical advantage.

However, there is no need to be in orbit to obtain it.

More telling, though, is the need to be careful what one asks for.

The US is essentially immune to air attack.

Until, that is, we orbit weapons.

Then our oceanic buffers become worthless.

October 30, 2008 7:52 PM  

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