Friday, November 6, 2009

Fantastic Future Friday: Space Based Solar Power

In my earlier posts on Alternative Energy Sources I concentrated on small-scale power sources for the end user. I did that because coming from the energy field I know that the US needs to work on either saving energy or finding new energy sources that add up to 1.5% of our current energy usage every year in order to maintain our lifestyle. This has to be done now and the working at the end user level is the quickest way to do it in the short term. However, It does quickly reach the point where you just can’t conserve any more so we need a large-scale solution.

Space Based Solar Power:

The concept is simple, in space the energy from the sun is 144% greater than here on Earth, under the thick atmosphere. There is also no weather to cause problems or oxygen to corrode the solar panels. So a large Solar Array would generate much more power than one here on Earth.

Every day enough energy falls on Earth in the form of Solar Energy to power civilizations current needs for a year, so solar power could supply all our needs for centuries.

As solar power releases no carbon dioxide, the only harm to the Earth will be the actual heat formed by using it. At today’s levels of energy use that heat is too small to be measured against the sun’s heat on the Earth. It will take several centuries of increasing power usage for solar from space to have a noticeable effect.

Experiments have shown it is possible to beam that energy down to Earth in the form of microwaves at roughly 80% efficiency.

So all we have to now, do is get them up there.

Right now that is to only weak spot in Space Based Solar Power for use here on Earth.

In order to be useful, a space based solar power array would need to be kilometers wide, vastly larger than anything we have ever tried to build in space before. So building it would involve launching more weight into space then we have ever tried.

In order to lift the current generation of solar panels in a large enough volume to build a 3 gigawatt power station, it would require lifting 80,000 tons into low Earth orbit, or roughly 3,000 Space Shuttle launches. (If my math is wrong Stephanie B will correct it in the notes.) This means it is probably impractical at this time, but there are a few emerging technologies that can overcome this limitation in the next decade.

Current solar panels are 14% efficient, but the newest generation panels are 40% efficient reducing the size (and weight) needed by two thirds. With more people installing small-scale solar systems in their homes the demand for efficiency will increase and over the next decade their weight/power will reduce, so less weight will be needed to be sent into low Earth orbit.

The Ares V is classified as a Super Heavy Lift Launch System as opposed to the Shuttle which is “merely” a Heavy Lift Launch System. It will be able to lift 188 Tons as opposed to the Shuttle’s 25 Tons.

If the Ares V is successful in 2018 and solar panel efficiencies continue to increase over the next decade. Within 15 to 20 years it will be practical to build a solar power array in space freeing us from the need for fossil fuels, and that will lead to a fantastic future.


Stephanie B said...

It sounds simple, but, in reality, not so much.

Technically, your numbers are about correct IF we are going to Low Earth Orbit(though I prefer to do calculations in metric). 80K short tons=239 ISS. That's a lot of hardware.

Except, we don't want to take something with a high surface area into LEO. Not only is there just enough atmosphere to cause considerable drag, which means that you'd need to devote resources (quite a bit) to adjusting orbit - so it will weigh more. LEO is also up to its eyeballs in orbital debris. The high surface area required makes this very very susceptible to orbital debris that not only can degrade or ruin solar arrays but, more importantly, add to the level of orbital debris with each major impact.

It is also far harder to have reliable reception stations unless you're somewhere like geostationary orbit (which the Shuttle can't get anywhere near - and the payload for higher orbits drops precipitously).

No matter how you slice it, if solar panels become cheap, it is easier to maintain and install (and way cheaper) solar panels here with no loss and they're right at ths source. Plus, with people able to pocket the advantages themselves, you can spread the investment.

Sounds cool, but I'm not convinced it will ever be practical. And I love solar power.

Project Savior said...

I was running short on time so I didn't get into the fact you'd need to move it from LEO to GEO. But if its generating 3 Gigawatts you can use that (or even a small fraction of that) to power an ion engine to slowly change its orbit from LEO to GEO.
As far as costs, the world currently spends $7 billion a day on oil and that is expected to rise as the world recovers from from the Great Recession. If solar panels could come down in weight to a tenth of what they are now and the Ares V is no more expensive to launch than the shuttle, then it would be practical by 2025 to 2030.

Stephanie B said...

Except, if they come down in cost, you might as well just give everyone a few for their rooftops and it will be just as effective at about the same cost, but without all one's eggs in one basket.

Project Savior said...

Oh wait 'til Friday, this is the just the beginning after all the title of this series is Fantastic Future - And this is a 1st step.