You are not logged in.
This topic is inspired by Calliban's support for Methanol as an energy storage medium.
On Earth, oxygen is readily obtained from the atmosphere. On Mars, all machinery that uses a partially oxidized material such as Methanol will have to carry an oxidizer along. It appears that the mass of the oxidizer is likely to exceed the mass of the fuel.
Liquid Oxygen might be attractive if the application is such that the oxygen can be consumed immediately (or at a rate that precludes loss due to boil off).
However, for long term storage of an oxidizer, there appears to be at least one attractive candidate and there may be others.
In Post *3, I've asked Gemini to think about the problem, and to put us some number to help us understand the design tradeoffs.
This topic is available for development of detailed solutions for vehicles for transportation or job site activity.
(th)
Offline
Like button can go here
This post is reserved for an index to posts that may be contributed by NewMars members.
Index:
Post #3: Gemini review of options for vehicles using methanol as the fuel on Mars.
(th)
Offline
Like button can go here
I asked Gemini to think about the tradeoffs for design of a vehicle for use in Mars, if the working fluid is Methanol.
Executive Summary: Storable Oxidizer and Fuel Architectures for Martian Vehicles
Evaluating energy storage and propellant options for Mars surface vehicles requires balancing volumetric efficiency, thermal storage constraints, and local resource availability. This summary reviews the trade-offs of using liquid methanol as a carbon-based fuel, compares non-nitrogen oxidizers, and presents a dual-oxidizer transit strategy.
1. Methanol as a Liquid Energy Carrier
Methanol (CH3OH) provides a stable liquid fuel at ambient temperatures and pressures. While hydrogen requires heavy cryogenic or high-pressure containment, methanol carries approximately 99 grams of hydrogen per liter within its liquid structure at room temperature. On Earth, atmospheric oxygen fully oxidizes methanol. Away from Earth, the full oxidizer mass must be carried or generated locally.
2. Evaluating Non-Nitrogen Oxidizers
Nitrogen is a scarce element in the Martian atmosphere (~1.9% of atmospheric volume), making nitrogen-based oxidizers (such as Nitric Acid or Nitrogen Tetroxide) undesirable for open-cycle surface combustion. Organic hydroperoxides like tert-Butyl Hydroperoxide (C4H10O2) are net oxygen-deficient and act as fuels rather than oxidizers.
The two primary non-nitrogen oxidizer candidates for pairing with methanol are:
* Liquid Oxygen (LOX): O2 (Cryogenic at -183 deg C)
* High-Test Hydrogen Peroxide (HTP): 98% H2O2 / 2% H2O (Ambient liquid)3. Mass and Volume Requirements per 1 Metric Ton of Methanol
To achieve full stoichiometric combustion of 1,000 kg (1.26 cubic meters) of methanol:
CH3OH + 1.5 O2 -> CO2 + 2 H2O
or using hydrogen peroxide:
CH3OH + 3 H2O2 -> CO2 + 5 H2O
Methanol Fuel Base: Mass = 1,000 kg | Volume = 1.26 m3 | State = Ambient Liquid
* Option A (Liquid Oxygen): Mass = 1,498 kg | Volume = 1.31 m3 | State = Cryogenic (-183 deg C)
* Option B (98% HTP): Mass = 3,250 kg | Volume = 2.27 m3 | State = Ambient Liquid
* Total System (Methanol + LOX): Mass = 2,498 kg | Volume = 2.57 m3
* Total System (Methanol + HTP): Mass = 4,250 kg | Volume = 3.53 m34. Operational Strategy: Dual-Oxidizer Transit and Standby Architecture
While 98% HTP imposes a 2.17x mass penalty over LOX due to bound water content, it requires zero active cooling hardware. Combining both oxidizers yields an optimized operational profile:
Outbound Transit (LOX-Dominated): The vehicle consumes LOX immediately during high-power transit. By matching the consumption rate to or above the natural boil-off rate, active cryocoolers and heavy vacuum Dewars are eliminated.
* On-Site Standby (HTP-Dominated): Once at a remote work site, the vehicle switches to HTP for power generation and site operations. HTP remains a stable liquid across standard storage cycles without loss of inventory.
* Auxiliary Utility: HTP can also be catalytically decomposed over a silver bed (2 H2O2 -> 2 H2O + O2 + Heat) to supply hot gas for mechanical drive, heat, or breathable oxygen recovery.
(th)
Offline
Like button can go here
As a follow up, I asked Gemini to think about what it will take to supply fuel and oxidizer for a landed expedition and construction operation on Mars.
Executive Summary: Feasibility of Integrated Methanol, LOX, and HTP Production on Mars
Evaluating an in-situ resource utilization (ISRU) facility capable of co-producing methanol (CH3OH), liquid oxygen (LOX), and high-test hydrogen peroxide (HTP) presents a highly viable engineering profile. A unified plant design minimizes total landed equipment mass by sharing primary feedstocks, thermal loops, and mechanical infrastructure.
1. Shared Feedstock Processing
All three target liquids consist solely of carbon (C), hydrogen (H), and oxygen (O). On Mars, these are derived from two primary sources:
Atmospheric Carbon Dioxide (CO2): Captured via cryogenic freezing or mechanical compression.
Subsurface Ice or Atmospheric Water (H2O): Extracted, filtered, and purified.
Because all output streams rely on identical raw inputs, the heavy front-end extraction units (mining drills, soil melters, atmospheric intake pumps) are fully shared rather than duplicated across separate production plants.
2. Simultaneous Co-Production Mechanics
Water electrolysis is required to generate the hydrogen needed for methanol synthesis:
2 H2O -> 2 H2 + O2
This reaction naturally releases a massive volume of pure oxygen as a primary byproduct.
Methanol Production: Catalytic hydrogenation of carbon dioxide combines hydrogen and carbon dioxide: CO2 + 3 H2 -> CH3OH + H2O.
LOX Production: The excess gaseous oxygen from electrolysis feeds directly into the cryogenic liquefaction train to produce LOX.
HTP Production: Direct electrochemical synthesis or partial oxidation pathways route a portion of the water and oxygen streams into hydrogen peroxide (H2O2) concentration loops.
This creates a self-balancing system where generating the fuel automatically yields the exact oxidizers required for the dual-oxidizer vehicle strategy.
3. Suitability for Autonomous and Teleoperated Deployment
A chemical processing architecture is particularly well-suited for early robotic deployment before human arrival:
Fluid-Based Operations: Modern chemical synthesis relies on pumps, pressure differentials, and automated valves, minimizing the need for complex robotic arms or manual maintenance during routine runs.
Energy Scaling: Production rates can be directly throttled to match available power, whether driven by continuous nuclear reactors or daytime solar arrays.
(th)
Offline
Like button can go here