1. “Bulk Gas Generation and Storage Systems of the Mars Settlement”
Damon Ellender
Programming Team

2. Design Goals
Design a Bulk Gas Plant and associated processes, located on Mars, to meet settlement and manufacturing needs for O2, H2, CH4, N2/Ar2 production and storage.

3. Design Assumptions Gas Composition as specified by NASA
Ready source of water available
Where possible, known and proven techologies are used
CH4 stored and used for fuel
Initial Storage vessels imported from Earth

4. Process Assumptions Electrolysis: Sabatier Reactor:
2H20=> 2H2 + O2
Sabatier Reactor:
4H2 + CO2 => 2H2O + CH4
Compression and Cooling:
Atmosphere => CO2 (l or s) + N2 (g) +Ar2 (g)
O2 Liquefaction and Storage:
CH4 Liquefaction and Storage:
N2/Ar Liquefaction and Storage:

5. Process Details Electrolysis: Sabatier Reactor: 2H20=> 2H2 + O2
Gibbs Free Energy: DG= kJ/mol
1 Bar , 298K
Sabatier Reactor:
4H2 + CO2 => 2H2O + CH4
Exothermic after startup
1 Bar, 873K

6. Electrolysis-Sabatier Process
Basic Electrolysis assumed
Hydrogen the limiting factor
All water from Sabatier Process recycled

7. Gas Liquefaction and Storage

8. CO2 Basic Separation
Compression chosen to 20 Bar to keep CO2 in liquid phase for piping and storage

9. Compression and Cooling
Inter-
Cooling
Work (kJ/kg)
Specific
DS=0
Dt=0
Bar (Differential)
Compress Mars Atmosphere from .07 to 20 Bar. Provides CO2 Liquid phase
Worst Case Specific Work(Isentropic): -421 kJ/kg
Best Case Specific Work(Isothermal): -199 kJ/kg
Isentropic Dt=~500K requires Inter-cooling: -747 kJ/kg
Additional Compression Cooling to liquefy Ar/N2 gas: -120 kJ/kg

10. Storage Vessel Design Storage for 4 Months full usage
Volume (m3)
Storage for 4 Months full usage
Higher Pressures Selected to minimize imported pressure vessel mass

11. Storage Vessel Design Spherical Vessels
Mass (tonne)
Spherical Vessels
Maximum Allowable Working Pressure (MAWP)= ~42 Bar
Composite Vessels are expected to reduce Titanium Mass by 1/2

12. Phase One-(2 Years) Gas Production to Storage
Summary Power Matrix
Phase One-(2 Years) Gas Production to Storage
Assume full production to storage. Fill 1 Month Emergency Storage in 1 Year.
Instantaneous Demand
Long Term Storage
Gas
Daily Use  (kg)
Power   (kw)
Capacity* (kg/day)
Emergency Storage Requirement(kg)
Power  (kw) O2
57587 14
H2*
20.1 -
N2/Ar 4
1461
CO2
156
**16377
CH4
39.56
14439
***
CO2/Ar/N C&L 3
O2 C&L 2
CH4 C&L  1
Totals: 20
*100% Required for CH4 production
**110kg/day used in CH4 production, excess can be used for cooling.
***Requires some power at start-up, then process self sustaining.

13. Phase Two-(2 Years)All Gas Production to Manufacturing
Instantaneous Demand
Refining Needs
Gas
Daily Use  (kg)
Metals Usage (kg/day)
Plastics Usage(kg)
Power  (kw) O2 70
414
110
H2**
2.6
60.75 -
N2/Ar 48
CO2
21.8
1515
583.75
CH4
5.3
187
CO2/Ar/N C&L 30
O2 C&L 8
CH4 C&L  3
Totals:
151
**Includes H2 used for making CH4, not shown

14. Import Staging Phase 1 Import Listing Weight and Size Item Floor space
Volume m3
Mass kg
Assume 50% reduction using Composites
CH4 Storage Sphere(r=2.5)* 25
125
4500
(2250**)
O2 Storage Sphere(r=3)* 36
216
8000
(4000**)
Ar/N2 Storage Sphere(r=1.1)* 5 11
500
(250**)
CH4 HX
.25
.125
100
CH4 Sabatier Column 1 2
200
Electrolysis Cells
CO2
N+1 redundancy (est 2 small scroll units) 4
250
O2/CH4/N2/Ar2 Compressors
N+1 redundancy 3
600
O2/CH4/N2/Ar2 Heat Exchangers
400
Total Mass(kg)
14750
(8250**)

15. Import Staging Item Floor space m2 Volume m3 Mass kg C2H4 Column 1 1 2
Phase 2 Import Listing Weight and Size
Item
Floor space m2
Volume m3
Mass kg
C2H4 Column 1 1 2
200
C2H4 Column 2
m{C2H4} Reactor and catalyst 5 10
Electrolysis Cells 4 6
400
Inspection Equipment
Total Mass(kg)
1200