Numbers on H2 Energy
Lithium
There is >60kg of lithium carbonate in a 70kWh battery. 400 liters of water is used per kilo of lithium [7]. Water is a problem bcz while lithium rich water is pumped, potable water resources also shift.
The entire world reserve for lithium is estimated to be ~17 million tonnes.
According to EIA, estimated world energy consumption was 157,481 Terrawatt Hours in 2013. If we were to store today’s energy consumption one day in batteries,
consumed_one_day = (157481. / (365)) * 1e9 # Kwh
reserves = 17.0 # mtones
req = ((consumed_one_day / 70.0) * 60.0) / 1e9
print ("%d mil. tons" % req)
print ("%0.2f percent of available reserves" % ((reserves / req)*100.0) )
369 mil. tons
4.60 percent of available reserves
.. it would require over 20 times the amount of available lithium in the world.
Driving
UK drove 303.7 billion miles in 2013. Take miles driven in one day and assume energy it is stored in bats, with range 250 miles per 75 kwh bat, project it to world population,
uk_world_ratio = 113
mday = 303e9 / 365
lit = (mday / 250 * 60 / 1e3)
print ("%d tons" % lit)
print ("%0.2f mil tons needed globally" % (lit * uk_world_ratio / 1e6))
199232 tons
22.51 mil tons needed globally
which exceeds available lithium reserves (given that UK has 1/113th of world population)…
Grid and BEV
The EV has an overall efficiency of about 60%. Electric grid efficiency is 40%, 60% x 40% gives a total of 24%.
Assuming same electricity comes from panels to both processes, electrolysis is 80%, pipeline transfer is 97%, for FC car efficiency 34% efficient (same as gasoline car). For BE let’s say they store electricity 100% on some battery, lose 60% while transferring, and 40% in the car,
print (0.80*0.97*0.34) # h2
print (1.00*0.40*0.60) # be
0.26384
0.24
Pipelines can transmit 10 times the energy at one-eighth the costs associated with electricity transmission lines [8].
Gasoline
1 gallon is 2.56 kg. In Europe the gasoline price is about 9 dollar per gallon, or 3.51 dollar / kg.
Gasoline has a density of 32 MJ/L.
H2
1 kg has energy of 39.7 kWh (143 MJ).
At 500 bar, 33 kg H2 /m3.
At 350 bars density is 28 kg/m3.
At 300 bars density is 20 kg/m3.
Liquid hydrogen has a density of 8 MJ/L.
Personal Consumption
10 KW / person, based on first world standards.
Typical energy requirements of household items
Single burner electric stove: 1500 Watts TV: 80-400 Watts Fridge: 100-250 watts
HFC Cars
A Nexo tank carries 210 kWh of energy. The car can travel 756 km on a full tank [3], the tank capacity is 6.33 kg. There are actually three tanks, each at 10,000 psi [4].
For the Toyota Mirai, the energy capacity of the fuel-cell vehicle’s 5 kilograms of hydrogen, compressed at 10,000 psi, is more than 150 kilowatt-hours [5]. Max range 500 km, 1848 weight,
F = 1.848*200
w = (F*500*1000) / 3600.
print ( w / (150*1000) )
0.34222222222222226
Solar panels
Sun energy falling on Earth
1000 W/m2
Solar panel efficiency is 20%
Electrolysis
Current best processes for water electrolysis (PEM or alkaline electrolysis) have an effective electrical efficiency of 70–80%, producing 1 kg of hydrogen requires 50–55 kW⋅h of electricity [1].
Ammonia
11 MWh/ton ammonia can be generated by renewable energy, solar, tidal, or wind. “Crackers” that generate H2 from ammonia are about 76% efficient [6].
Desalination
Energy consumption [2] of seawater desalination has reached as low as 4 kWh/$m^3$,
Fossil, Oil
How much solar panel space would Saudi Arabia need to produce its crude output’s equiv energy,
Production is 9.01 million barrels / day (Nov 2020).
1 Barrel of oil is 136 kg. 1 barrel is 0.16 m3. Energy density of crude oil 158.4 Kwh/kg. 1 million barrels of oil can produce half a million barrels of gasoline. Gasoline energy density is 12.88 kwh/kg.
Sun energy falling on Earth 1 kW/m2, 24 KWh/m2 in a day.
Panel efficiency 20%, sunlight availability 50% (highest for SA)
solar_kwh_day_m2 = 24*0.20*0.50
oil_energy_day = 136 * 9.01 * 1e6 * 158.4
area = (oil_energy_day / solar_kwh_day_m2)
print ("area of %0.2f km^2" % (area / 1e6))
print ("square with one side %0.2f km" % (np.sqrt(area) / 1000.0))
area of 80873.76 km^2
square with one side 284.38 km
An area 290 km x 290 km. of panels. SA Rub’ al Khali desert is 650,000 km^2, 1/7th of that is needed approximately.
References
[1] https://en.wikipedia.org/wiki/Electrolysis_of_water
[3] https://h2.live/en/wasserstoffautos/hyundai-nexo
[4] extremetech
[5] Business Insider
[6] Ammonia Energy Association
[7] Danwatch