Hydrogen Production

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Basics

  • This page explores various methods of hydrogen production
  • 39.4 kWh of electricity and 8.9 liters (l) of water at normal conditions (25 C and 1 atm) to make 1 kg of hydrogen [1]
  • Electrolyzers (alkaline and PEM) are 50-80% efficient [2]

Hydrogen “Colors”

Water Treatment

  • Water deionizer - $300 - [3]
  • Water distiller - 6 gal/day - $65 [4]

Cost

  • This article states that hydrogen cannot be produced cheaply. [5] However, if we use OSE's 1 cent/kWhr cost of electricity as documented in the Seed Eco-Home PV System, with alkaline electrolyzers (see Hydrogen Production, the cost of returning that electricity through solar hydrogen is 5 cents per kWhr. See Round-Trip Electricity from Hydrogen.
  • Alkaline electrolyzer generation cost is -
  • Hydrogen appliance - $7.60/kg hydrogen - for a machine that produces one of per day and lasts 30k hours. Cost of the hydrogen is largely the electrolyzer cost. [6]. Note that this source mentions alkaline electrolyzer at about $2/kg capital costs, but Chinese prices are much cheaper..
  • Hydrogen generator - 6kWhr/cu m. 1 cu m is 45 moles, or 90 grams of hydrogen. [7] This system would thus cost 12 cents (conservative) electricity cost per 90 grams using the OSE PV system (2 cents per kWhr). This is $1.32/kg of hydrogen. The GGE is thus $1.32/gallon equivalent cost of gasoline. The 6kWhr/cu m is reasonable, in that it reflects a 66 kWhr cost of electricity per kg of hydrogen - the standard value for an alkaline electrolyzer implying 60% efficiency.
    • Implications - if electrical cost is the main cost of hydrogen production - then cost of hydrogen is <$2.64 GGE (taking 50% electricity and 50% electrolyzer cost). This already matches gasoline.
  • $3.33/kg cost for power plant storage - [8]
  • From steam reforming of methane - $1.25/kg - [9]
  • Extreme existing cost reduction case - Based on Seed Eco-Home PV System, we go with 50 cent/kW cost of panels with large shipping orders (40 cents for a container - in which container shipping is $500, compared to full trailer load). Then we reduce system cost 30% by feeding electrolyzers directly instead of using inverters, chargers, and storage. Then we go from 2 cents to 1.4 cents with this 30% reduction - to 1 cent by 40 year lifetime instead of 25 year lifetime of panels. So we go down to 66 cents per GGE in terms of electricity costs. Capex for electrolyzer is discussed below, but is favorable and in the worst case the capex cost per GGE is comparable to the electrical input cost.
  • Paper showing $5/kg production, at 1000 kg/day scale. Most of the cost is electricity. [10]. Assumes 5c/kwhr cost. Thus, right there we have <$2.5/kg cost of hydrogen if electricity cost were negligible compared to 5c/kwhr.
    • Conclusions in paper clearly state that in larger systems, electrical cost is the main cost of hydrogen.
  • $3.2Euro/kg - [11]
  • Capital costs of $1k/kw_e cost for 1kW electric input- [12]
  • Electrolyzer is $1k/kw and 75000 hours life for alkaline electrolyzers - [13]
    • Capital costs of generation: 66 hours per kg equivalent. Electrolyzer can make 1000+ gallons of gasoline equivalent- per $1000. So capital costs are $1 per gallon. This reflects the industry, where capex of electrolyzer is comparable to electricity costs of producing hydrogen.
  • Check.pngCost of electrolyzer is 50 cents per kg H2 [14] - see first 2 figures showing capital costs of $0.50/kg. If we believe this figure, then the distributed production route yields 1/3 the cost (55 cents vs $1.6), adding 17 cents to the 55 cent OSE production cost of hydrogen. The OSE cost of hydrogen production is thus 72 cents per kg, not counting compression/storage. With compression, it is 2/3 more - or a total of $1.2 per kg.

Electrolyzer Design and Capital Expenditure

  • From Solar Hydrogen Chronicles, we have $100 cells which use stainless steel and take 100W each (24v made of 2v cells, running up to 40A).
  • Ultimately, we are talking about stainless steel electrodes, a separator, and potassium hydroxide.
  • The cost of materials requires is low - these are all COTS materials. This indicates that based on stainless steel costs of around $1 (see Commodity Prices), the electrolyzer cost should be significantly less than $100/10lb - and more like a dollar a pound of dry weight.
  • If it costs $1000/kW hydrogen production to get $1/kg capex for hydrogen - then corresponding reduction in capex gives corresponding reduction per kg cost - based on a simple $1000 capex to $1/kg hydrogen costs.
  • Note that a minor portion of cost goes to gas conditioning - so the stack cost is the dominant factor - Ae cost.png (from [15]). Thus, the cost limit for electrolyzers is the cost of stainless.
  • From Wikipedia [16], hot dip galvanized nickel is a good and cheap electrode - [17]

Research

Energy Requirements

  • about 50kWhr [18] to produce one kg of hydrogen. At electrical costs of 10 cents per kWhr, that is $5 per kilo, equivalent to a $5/gal of gasoline cost for the Energy Density.
  • For the Seed Eco-Home built in 2016 - the total installed marginal cost of 3kW is $2000 in 2017 - See Seed Eco-Home PV Cost. This could produce 1 kg of hydrogen in 3 days. Perfect. Annual cost of fuel at $3/gal is $1200 - 400 gallons at 25 mpg - for 10k average miles. So we would get free fuel after 2 years of use.
  • If cost over lifetime is considered - 20 years at 3kW of production yields 20*365*6*3 kWhrs = 131,400 kWhrs. This yields an energy cost of 1.5 cents per kilowatt hour. Or equivalent to 80 cent per gallon gasoline cost not counting electrolyzer cost.
  • This makes a great case for the Seed Eco-Home + Hydrogen Filling Station + Open Source Hydrogen Car + Microfactory + Aquaponic Greenhouse as a productive unit for civilization with automated food harvest and passive electricity and fuels production.

Methods

Electrolysis Of Water

Wind Hydrogen

See $6k concept design of 20 kw wind turbine - Deka-kW_VAWT_Wind_Turbine. If the think lives for 20 years, and has a median capacity factor of 40% - [19] - then we are getting 5 kW of power for $6k. Compared to 3kW for $2k, but with 1/2 the capacity factor of wind - the solar option translates to 3kW for $4k compared to wind. Thus, the wind power option is approximately similar to PV. Except the wind can be self-manufactured, but probably has higher maintenance costs. However, if the wind turbine lasts 100 years, then we have a significant advantage. Further, if we could get a larger system than 20kW for wind - then we could be at an advantage in cost performance.

H from Aluminum

One way to generate hydrogen is by reacting aluminum with base such as NaOH.

This company promises $2000 home scale units for producing hydrogen at $1 per Kg

https://www.computerworld.com/article/3066072/sustainable-it/new-generator-can-halve-cost-of-hydrogen-used-to-power-buildings-cars.html

Steam Reforming of Hydrocarbons

  • This breaks down hydrocarbons into hydrogen and other byproducts (Usually carbon dioxide or carbon monoxide, although not always)
  • This is usually done with fossil fuels, but it could use renewable biofuels such as biodigester gas (either impure, or purified to pure methane)
  • Wikipedia Page on Steam Reforming

Artificial Photosynthesis (Also Called Photocatalytic Production)

Biohydrogen

  • This uses genetically modified microorganisms to produce hydrogen, either by modified photosynthesis, or by modified fermentation of sugar
  • Wikipedia Page on Biohydrogen

Gasification / Pyrolysis

  • Gasification (and to a lesser extent Pyrolysis ) Produce Hydrogen along with other products
  • The Water-Gas Shift Reaction can tune the Syngas to contain mostly Hydrogen and Carbon Dioxide
  • Novel method called "hydrogen production by the integrated novel gasification" or HyPr-RING may be worth a look as well

Internal Links

External Links

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