Hydrogen Storage

• Electrolyzers can produce hydrogen at pressure, so a compressor is not needed.

Calculations

• Cost targets - https://energy.gov/eere/fuelcells/hydrogen-storage
• 1kWhr=3.6MJ. 1 kG of hydrogen is 142MJ/kg
• Cost for car tanks target - $15/kWhr - or about 40x for 1 kG - $600/kg. (above reference)
• Cost or stationary storage goal - $1000/kg - [1]

• Compare to propane tank, 1000 gal, 100 PSI -

High Pressure Hydrogen

• A high pressure steel tank is about $500 - [2]
• The simplest tank that can be used is a steel tank for up to 200 bar. This appears to be the lowest cost option. [3]

• Standard tanks are 55" high and 9" wide. with 45x9 inch usable size. 50L? - about 12 gallon, yes, 50L. If 200 atmospheres, that is 2400 gallon equivalent. 4 of these store 10000 gallons - 1.7 gallon gasoline equivalent - but the efficiency of a hydrogen engine is 2x that of gasoline, so it's effectively 3.4 gallons by comparison. That is acceptable for a microcar, though cylinder weight is 143 each or 572 lb for the tanks themselves - a significant tradeoff for a 750 lb microcar. In the first iteration, a microcar could use 1 of these as a proof of concept for a 100 mile designed range at 750 lb of weight.

Storage Tank Suppliers

• 700 bar, 20 gallon - [4]. RFQ submitted 1/27/18
• In-ground storage, 2200 PSI - 14"x40' - [5]
• Low, medium, and high pressure storage options - [6]
• Pictures of storage tanks - [7]

Cryogenic Storage

• Ultra High Density
• Can be done using a Delwar, a pure hydrogen gas source, and a cheap cryocooler
• A diy cryocooler could possibly be made to reduce costs further

Storage as a Synthesized Fuel

• Convert to Methane by the Sabatier Reaction
• That can be compressed/liquified as is or it could be further converted into other fuels
• Methanol can be made from methane via the following process Listed Here
• Dimethyl Ether can be made from Methanol This Details How
• Dimethyl Ether Can be Catalytically Converted to Hydrocarbons such as Gasoline This Details How
• Hydrogen + Carbon Monoxide can be directly converted to hydrocarbons via the Fischer Tropsch Process

Links

• This reports the cost of tanks at low-thousands scale for a car - [8]
• Energy.gov state of art technology report - [9]

• In an open source economy, these costs make hydrogen storage feasible at today's prices - deployable via community-supported manufacturing.

Internal Links

• Gas_Storage_in_PVC_Pipe - 10000 gal STP is 1.7 kg of hydrogen.