Solar thermal power

Decimator · 2011-12-16 12:31:07

How do others envision solar thermal power on Mars? It seems logical to me to place the heat radiators/condensers within the colony itself, to reduce losses. This would make the system less efficient for electricity production, due to the lower temperature gradient, but the waste heat would end up heating the colony instead of being waste.

Also, which solar design would be most efficient in labor and raw materials vs power generated? What resources can be substituted to sacrifice efficiency for labor savings?

louis · 2011-12-16 12:50:07

Decimator wrote:

How do others envision solar thermal power on Mars? It seems logical to me to place the heat radiators/condensers within the colony itself, to reduce losses. This would make the system less efficient for electricity production, due to the lower temperature gradient, but the waste heat would end up heating the colony instead of being waste.
Also, which solar design would be most efficient in labor and raw materials vs power generated? What resources can be substituted to sacrifice efficiency for labor savings?

What matters on Mars - at least in the early stages of the colony - is not so much the efficiency of the system, but the mass that has to be ferried to Mars to put in place effective energy generation. We need to keep that to a minimum.

On that basis I favour photovoltaic panels for the initial phase and wouldn't waste too much time on solar thermal which would require piping. However, I would agree with you heating up of water within the hab will be a good idea - that way we won't need to heat much over night.

Once the base is established, I think it would be best to move on to solar concentrator technology and use concentrated solar radiation to heat a boiler and thus power a steam engine which in turn would generate electricity. We may wish to use the concentrated solar radiation to heat water tanks close to the hub. I am not sure - I always think of the problem of seals around any entry point for pipes .We want to keep seals to an absolute minimum.

Gregori · 2011-12-19 10:24:42

I don't think photovoltaic panels would be such a good idea, at least initially for Mars because of their mass. The panels would be light enough but you would have to choose between landing at the martian poles or bringing massive fuel cells or batteries. To store enough energy for night time usage, you have to double the amount of panels you bring. The distance from the Sun means that panels have to cover far more surface area than if they were near Earth. This mass all add up.

I think a small nuclear reactor for base load power would be far more flexible. This guarantees a minimum power supply day and night. This can then be supplemented and expanded with solar panels without the need for massive batteries.

Mars can have horrible global dust storms and I think this is a greater risk to the crew using solar than the use of nuclear when you look at the odds.

By the time we actually execute a Mars mission, there may be much greater breakthroughs in batteries making them lighter and store more energy. But thats not something that can be counted on any more than the warp drive. I think a mix of nuclear and photovoltaic makes more sense overall.

louis · 2011-12-19 17:18:56

Gregori wrote:

I don't think photovoltaic panels would be such a good idea, at least initially for Mars because of their mass. The panels would be light enough but you would have to choose between landing at the martian poles or bringing massive fuel cells or batteries. To store enough energy for night time usage, you have to double the amount of panels you bring. The distance from the Sun means that panels have to cover far more surface area than if they were near Earth. This mass all add up.
I think a small nuclear reactor for base load power would be far more flexible. This guarantees a minimum power supply day and night. This can then be supplemented and expanded with solar panels without the need for massive batteries.
Mars can have horrible global dust storms and I think this is a greater risk to the crew using solar than the use of nuclear when you look at the odds.
By the time we actually execute a Mars mission, there may be much greater breakthroughs in batteries making them lighter and store more energy. But thats not something that can be counted on any more than the warp drive. I think a mix of nuclear and photovoltaic makes more sense overall.

So you are relying on one integrated system for the whole of your energy supply? You're not taking a spare? Just the one reactor. Have reactors never ever gone wrong? That's certainly a high risk strategy. I think you need to have at least two full size reactors - in which case your mass benefit is lost.

And aren't you going to be exploring the planet. What with? You mention solar panels, but if you are going to run a rover, power drills and keep people alive, you are going to need a lot of energy. In other words, you will have to take a lot of panels anyway.

As for chemical battery storage, I don't think we need to go over the top. Nightime heat storage doesn't require chemical batteries - rocks and water will do. You don't need to run washing machines, electric cookers or other major juice-users during the hours of darkness. For longer term storage we should use methane (produced during the day from water and the atmosphere).
The panels aren't so very different from those on Earth - it's about 40% IIRC. But remember - these panels will be absolute top of the range - far more efficient than your average panels on Earth. They will probably be comparable with the panels put on houses on Earth.

Yes there are global dust storms, but experience with the solar panels on the Rovers shows they never perform at less than 20% of clear conditions, which will be more than enough to maintain all essential systems. With methane storage (possibly beginning before the human landings, using a robot operation), there will be no lack of power.

Decimator · 2011-12-19 18:04:42

Louis, Gregori, I wasn't really talking about what to send with the colonists, but what the colonists could build in situ. Nuclear reactors and photovoltaic panels both require serious infrastructure and diverse resources. Glass and metal for a solar concentrator? Not so much. Once Mars has numerous settlements to collect various resources, then more complex options will become viable.

Louis, can you get around the problem of seals by using a sterling engine instead of a steam turbine?

Am I correct that sunlight-mirror-heat-electricity will be more efficient than sunlight-photovoltaic-electricity-heat?

louis · 2011-12-19 18:31:57

Yes, these are two different problem areas. For Mission 1, as I have indicated I think robot pre-landers could manufacture methane so that an ISRU resource is available when the humans arrive.

I'd say - as we see with the Mars Rovers, that PV Panels do not require a hugely complex infrastructure and can be deployed immediately. A nuclear reactor (unless placed in a mobile vehicle - in which you have more tonnage) will require a period of deployment.

In terms of what humans can manufacture on Mars, they should be able to produce polished aluminium or steel reflectors.

I think reliability can be an issue with sterling engines - well that's what I've read, which is why I tend to think in terms of steam engines. However, sterlings can be quite small scale, so I can imagine the colonists building a series of small such engines. I think with Missions 1 and 2 the colonists will be experimenting to see what they can produce and how easily. Of course they won't be doing everything by hand - they will have taken with them sophisticated furnaces and metal working equipment.

I don't know about the efficiency figures. It's probably quite complicated. For instance, as far as I know all electrical equipment produces waste heat - but that "waste" heat will be very useful inside the hab, to heat it. (The hab will likely be insulated with v. effiicent aerogel, so we won't need huge amounts of heat energy.)

SpaceNut · 2011-12-19 22:45:51

We talked about this in the old toehold thread but to go back in time a bit....
The thrusters that we land with could be reused in a blast furnace senerio to make glass and some metals from the methane that is made to return home. These materials can then be fashioned into domes and so much more....

SpaceNut · 2019-12-11 07:18:44

Temperature rise for size of the reflector.

How to calculate the temperature of a receiving point from concentrated solar power?

https://www.builditsolar.com/Projects/C … rating.htm

Calliban · 2019-12-11 16:25:37

The ultimate temperature limit is the temperature of the sun, as at this temperature the receiver will have the same emission spectra as the sun's surface.

The low density of the Martian atmosphere should be beneficial in terms of deploying thin reflectors, so long as they can be retracted during dust storms. Using an S-CO2 power conversion cycle at a hot temperature of 1000K and a radiator temperature of 300K, thermal efficiency exceeding 40% should be possible even in small scale systems.

There are also opportunities for exploiting the high day-night temperature variations of the Martian surface. Such a system would be technologically simple.

Last edited by Calliban (2019-12-11 16:30:59)

SpaceNut · 2019-12-11 17:37:34

It works well here on earth in these areas and not so much the further north you go as shown in the earth image:

That still is not calculating the M^2 for the reflector to the focal limit location distance of the recieving dimensons M^2 open or closed chambered to what we would want for the heat exchanger temperature rate of transfer. This is where we need to be in order to design and know all of the component mass needed to make the system work.
We do have a flexible mylar reflective material to do testing of furling and unfurling of a rollered system with rails for deploying the reflective materials on mars but what of the fatique caused by the cold in doing this everyday, weekly or monthly as it might be required to not damage tyhe material? Not to mention that the rail will start to bind over time as dust and dirt build up and scratch the sliding surfaces.

SpaceNut · 2019-12-11 19:09:20

Of course to capture the maximum energy you need to have it able to move.
latest?cb=20130209210342

This is a manual hand crank but it could be electrical as thats a matter of motor size to make it move. Next up is the detector circuit for when it it in alignmment.

300?cb=20130218192440

Of course its still needs to be setup correctly for it to work at its best
http://www.solarelectricityhandbook.com … lator.html

SpaceNut · 2021-12-05 17:13:51

another energy capture and creation as heat.

SpaceNut · 2023-11-24 17:57:26

UK’s unique heat-capturing glass tubes are keeping US fishermen warm

AA1ktMuX.img?w=768&h=432&m=6

The system is looking to dislodge natural gas heating as the primary heating source for the building and has so far helped reduce 40 metric tons of carbon emissions.

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#1 2011-12-16 12:31:07

Solar thermal power

#2 2011-12-16 12:50:07

Re: Solar thermal power

#3 2011-12-19 10:24:42

Re: Solar thermal power

#4 2011-12-19 17:18:56

Re: Solar thermal power

#5 2011-12-19 18:04:42

Re: Solar thermal power

#6 2011-12-19 18:31:57

Re: Solar thermal power

#7 2011-12-19 22:45:51

Re: Solar thermal power

#8 2019-12-11 07:18:44

Re: Solar thermal power

#9 2019-12-11 16:25:37

Re: Solar thermal power

#10 2019-12-11 17:37:34

Re: Solar thermal power

#11 2019-12-11 19:09:20

Re: Solar thermal power

#12 2021-12-05 17:13:51

Re: Solar thermal power

#13 2023-11-24 17:57:26

Re: Solar thermal power

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