A Reddit user over in r/ColonizeMars (u/3015) caught multiple errors in my menu planning sheet. (thread) These affected power, area and volume calculations. I've corrected these errors; the sheet is updated anywhere it is linked.
The per-person volume is still about 45 m³. The sheet now tracks 'tray' area and 'floor' area separately, with estimates of floor area required for a set of ceiling heights.
Most important is the power requirement for lighting. This increased significantly, from 5.7 kW per person to 22 kW per person.
Those energy levels seem extreme.
ReplyDeleteHave you thought about concentrated CO2 atmospheres for plants to grow in?
It's about 500 W/m³, or about 415 kWh per person per day using my assumptions.
DeleteI usually assume that the atmosphere system in the residential sections remove CO2 and pass it to the hydroponic sections in relatively high concentrations. We shouldn't exceed 1000 ppm for safety reasons, but we should try to stay above 500 ppm for productivity reasons.
Hi Chris, I'm wanting to suggest a topic for a blog post but it exceeds 4,096 characters. Can you e-mail me at: DougSpace007 (at Google's email)? Thanks, Doug
ReplyDeleteWhat's the general idea, if you could describe it briefly?
Deletecave you alos considered cooling needs - with that amount of energy that will ultimately turn itself into heat, you will need to get rid of it
ReplyDeleteEvery watt needs to be removed as heat eventually. When I do facility projections I add cooling on top of the total power draw. For a CO2 heatpump with CoP = 4 you add 20% on top of all other power requirements, plus a margin for fluid circulation. I think I've used 25% for each of the habitats I detailed so far.
DeleteA few comments:
ReplyDelete1. Increasing the hours of light/day in your spreadsheet *increases* the watts/square meter required, which makes no sense.
2. Your spreadsheet has wheat requiring far more light than other crops, at 140 mols/day. This doesn't make much sense to me, and if wheat really does require that much light, why would anyone grow it hydroponically?
As a sanity check, I Googled grow light requirements for indoor hydroponic marijuana farms, and this site says that the rule of thumb is 32 watts/square foot, which assuming that the lights are on for 14 hours a day, which the site says is also a "rule of thumb" works out to ~200 watts/square meter. https://www.urbanorganicyield.com/how-many-watts-per-square-foot-for-led-grow-lights/
I've also seen multiple websites claim that as a rule of thumb around 200 square feet of hydroponic growing area is enough to feed one person with current consumer-level tech. For example: "So what is the room required to feed one person in a year using hydroponics? An average adult will need around 200 square feet of growing area to grow his food required throughout the year." https://www.hydroponicsspace.com/can-you-live-on-hydroponics/
Putting the three "rules of thumb" together suggests that as little as 3.8 kilowatts per person to power grow lights might be sufficient.
The first point should read:
Delete"Increasing the hours of light/day in your spreadsheet *decreases* the watts/square meter required, which makes no sense."