Stirling or Steam Engines for power Generation on Mars?

[theropod2]

Likewise the moon no? Understanding of course that it was a pressurized and sealed unit. If oriented towards the sun on the lunar surface it seems that one side would be very very warm and the other very cold, giving you the temperature differential needed to increase output.

The trouble with the moon is there are long periods where the sun doesn't shine on portions of the surface.

Direct photovoltaic conversion might work far longer and more reliably than even the very best Stirling. Barring meteor damage current solar panels could last 50 or more years on the moon. If connected to deeply buried batteries the long periods of darkness could be addressed in storage. The moon itself might have the raw materials to build even more solar arrays. The reduced gravity might be a boon to the operation, and support structures could be far less robust than the mounting we need here on earth. The absence of wind loads also benefits solar arrays.

I like this proven technology more than mechanical conversion.

RS

[Ian S C]

Solar power, you work it out: Earth about 93,000,000 ml from the sun, Mars 141,500,000 ml from the sun, at that distance you need a solar reflector about the size of a football field to get enough power to send a radio message back to Earth, just to ask for a better power supply, let alone boil the water for the coffee.
Nasa is looking at Plutonium238, and Uranium dioxide, The Pu 238 one would produce 500W and use about 1Kg of fuel every 15 years. I think they would like 40KW for a base station power supply.
As the motor would be a pressurised one, it would be hermetically sealed, so the talk of a Stirling Engine not working in space is irrelevent.
Whether the engine is a free piston type (see Sunpower), or a thermomechanical generator, it matters little, as long as the most efficient is chosen. I don't think that for power generation you will see a crankshaft in space, although a rotative engine may be of use for some opperations, maybe a fan to blow some warmth around the living quarters. Ian S C

[theropod2]

Solar power, you work it out: Earth about 93,000,000 ml from the sun, Mars 141,500,000 ml from the sun, at that distance you need a solar reflector about the size of a football field to get enough power to send a radio message back to Earth, just to ask for a better power supply, let alone boil the water for the coffee.

Umm, the bold part above is demonstratively wrong.

Spirit and Opportunity, Mars surface probes, relied exclusively on solar cells for their electrical power and worked very well. Both do have a small nuke pile as an alternative heat source. They were only supposed to run for 90 days, and Opportunity is still working. While they relayed their data to both directly to earth, and to a satellite in Mars orbit, their antenna arrays are not as big as football fields, nor were the approximate 140 watt solar arrays as big as football fields. Do I need to post pictures and videos sent back (radioed) from these probes?

Curiosity, the most recent of our Mars probes, does use a nuke power source, but that's one large craft with a mass of on-board experiments all demanding power. The mobility of such a heavy craft also makes a solar array unworkable.

I'm talking about the moon where there are no dust storms, or clouds, as we see on Mars to cloud the solar cells, and that was the sole focus of my post. A solar array on the moon would be far more efficient than an earth based array simply because there would never be any cloud cover and these cells work better the colder they get. NASA employs vary large solar arrays on the ISS for a reason.

Nasa is looking at Plutonium238, and Uranium dioxide, The Pu 238 one would produce 500W and use about 1Kg of fuel every 15 years. I think they would like 40KW for a base station power supply.

Already been done, for a long time now. See Voyager probes. See Opportunity.

As the motor would be a pressurised one, it would be hermetically sealed, so the talk of a Stirling Engine not working in space is irrelevent.

Still a mechanical device, and eventually will fail. Repair/rebuild on the moon would be far more problematic than erecting a solar array. No moving parts in a silicone solar cell. I don't think it is currently possible to build a machine, with moving parts, that will last for 50 years of continuous service.

Whether the engine is a free piston type (see Sunpower), or a thermomechanical generator, it matters little, as long as the most efficient is chosen. I don't think that for power generation you will see a crankshaft in space, although a rotative engine may be of use for some opperations, maybe a fan to blow some warmth around the living quarters. Ian S C

NASA is looking into Stirling technology for some deep space probes, powered by nukes, but I think you'll find that for almost anything inside the orbit of Mars the first choice for direct power will be a solar array. This is a mature technology that has a proven track record. With improvements in battery technology a large solar array on the moon seems like the best choice for a long term installation.

R

[alihureiby]

mars is away from sun, so the temperature will be cold,
if you are in venus you can use stirling engine for generate.
hehehe just opinie

ali

[Hopper]

If you are going low-tech with limited materials as you say, a steam engine might be more practical. You can build the whole thing out of steel and iron. Plenty of old reciprocating steam engines ran generators in the old days. There is even a working sugar mill in Bundarberg, Australia, that is still running today with the crushers and generators powered by reciprocating steam engines, build during World War 2 when they could not import turbines from the UK or US and none were made in Australia.

Steam engines are way less fussy in the materials and tolerances used, and less fussy about friction in the bearings. Presumeably there would be no ball-bearing manufacturer on Mars yet.

Biggest problem would be producing the steam from solar but I guess big enough mirrors and lenses and it could be done. Many recip engines will run on quite low steam pressure.
Or is there geothermal energy from drilling down to the hot core, or steam geysers of Mars available? Does it even have a hot core??

[vamoose]

Also many liquids/solids will boil/sublimate in a low martian atmosphere, its a whole different ball game in low/no atmosphere situations. Steam engines (or could we call them material expansion machines), may have some use in martian exploration, depending on 'available source of processed material' and 'input/output of energy' .

vamoose

ps. i should add though, that in my opinion, the benefit of a Stirling engine is that you have a sealed system with a fixed working gas and all you need is a heat differential to derive usable energy...?!