Hydrogen Storage

Basics

• Although hydrogen if a good fuel, its storage can be complicated. Thus this page was made.

Cost

• Quote for a 350/700 bar type 3 80L tank is $3150 below quoted
• Storage in this tank is 2.5 gal fuel equivalent at 350 bar
• Optimal conversion of fuel to electricity is 14 kWh_e/gal. See Fuel Consumption.
• Thus the storage cost is $90 (tank alone, no plumbing) per kWh_e at these costs. Double pressure to 700 and add 100% for plumbing and cost is at $90 for this storage, 4x less than Lithium Ion batteries, and equivalent to Saturated Water thermal storage.
• These are critical numbers to understand to transcend resource conflicts

High Pressure Hydrogen

• 350-700 bar - [1] - - $3150 - 1400 gallons STP - 4.8 or 2.4 kg hydrogen at 700 or 350 bar. This is about 2.5 or 5 gallons of fuel equivalent. For a 100 mpg car, this is 250 or 500 mile range.
• Electrolyzers can produce hydrogen at pressure, so a compressor is not needed.
• 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.

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 - [4]

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

Storage Tank Suppliers

• 700 bar, 20 gallon - [5]. RFQ submitted 1/27/18
• In-ground storage, 2200 PSI - 14"x40' - [6]
• Low, medium, and high pressure storage options - [7]
• Pictures of storage tanks - [8]

Cryogenic Liquid Storage

• Ultra High Density
• Can be done using a Dewar, 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

Risks

1. Presentation to DOE from China, 2010, with links to contacts, https://www.energy.gov/sites/prod/files/2014/03/f12/cng_h2_workshop_4_zheng.pdf
2. Good overview, EU, With description of hydrogen storage cylinders , http://www.hyresponse.eu/files/Lectures/Safety_of_hydrogen_storage_notes.pdf
3. Lower Flammability limit 4%, http://www.hyresponse.eu/files/Lectures/Safety_of_hydrogen_storage_notes.pdf
4. Sales reflect acceptable safety with 20,000 fuel cell vehicles on the road and growing strong. https://www.statista.com/statistics/644545/global-sales-of-fuel-cell-vehicles/

Internal Links

• Gas_Storage_in_PVC_Pipe - 10000 gal STP is 1.7 kg of hydrogen.
• Open Source Fuels Construction Set

External Links

• Low cost cylinders in the $1500 range for 1 or $300 for 10 seem to be available, [9]
• This reports the cost of tanks at low-thousands scale for a car - [10]
• Energy.gov state of art technology report - [11]
• In an open source economy, these costs make hydrogen storage feasible at today's prices - deployable via community-supported manufacturing.
• Another USA ".gov" site on hydrogen storage