Lawrence Livermore team has demonstrated that electrolysis of saline water
produces not only hydrogen, chlorine and oxygen gases, the resulting electrolyte
solution is significantly elevated in hydroxide concentration, which are
strongly absorptive and retentive of atmospheric CO2.
Figure 1 to the right is a schematic
of the process that produces what they refer to as "super green" hydrogen.
case study of a hypothetical 100 MW OTEC plant analyzing the prospects of OTEC
technology by Dr. Subhashish Banerjee et. al (page 125) determined that
hydrogen production from a 100 MW OTEC plant would be over 35,000 kg/day.
Every mole of hydrogen produces a
mole of sodium that in turn precipitates a mole of CO2. A 100 MW OTEC would
therefore produce 12,775,000 kgs of hydrogen a year which would sequesters
562,000 metric tons of CO2 with the super green technique.
Full capacity OTEC (14 terawatts)
could therefore sequester about 79 billion metric tons/year by 2100 and return
atmospheric CO2 concentrations to safe levels.
Fourteen terawatts would generate
1.8 trillion kilograms of hydrogen each year, which in turn would be converted
to 16 trillion kilograms of water when energy is produced in a hydrogen fuel
cell or the hydrogen is burned in some other engine.
Since the average height of of land
is 840 meters, this water would have the potential to generate 4.3 terawatts of
hydro or about 4 times what the world is currently producing.)
Hydrogen and oxygen can be combined
in a stationary installation at any elevation to produce energy and water and
the head between where it is produced and where it is needed can be used either
to augment the system's energy output or to facilitate water distribution.
Hydrogen is a water as as
Compressed hydrogen has the
highest energy potential
by weight of non-nuclear materials. The most efficient way to produce
compressed hydrogen is to perform electrolysis in deep water. When performed at
a depth of 1000 meters the gas arrives at the surface pressurized to 100 bar.
Raising desalinated ocean water to
an average height of 840 meters consumes considerable energy.
Hydrogen on the other hand is
lighter than air and would rise from a depth of 1000 meters to any place on land
of its own volition. It is a
lifting gas because it is 14 times less dense than air. Above the surface
compressed gas has the same energy potential as
air energy storage systems.
Hydrogen is most frequently
associated with stationary or transportation fuel cells. In the latter case the
gas is compressed to between 350 and 700 bar for spatial and range
considerations but the
optimal operating pressure of PEM fuel cell systems in automotive or stationary
applications is about 6 bar.
The relationship between work
required and the compression of a gas is logarithmic so only 30% more energy is
required to compress a gas to 700 bar from 100. This extra work plus the
potential inherent in the gas at 100 bar is recovered when the pressure is
dropped back to the 6 bar used in the fuel cell.
In a fuel cell hydrogen is combined
with oxygen to produce electrical energy and water in a process that is
thermodynamically the opposite of electrolysis - the fuel cell produces the same
amount of energy as is consumed in electrolysis.
Hydrogen is the ideal energy
carrier because compressed it has the highest specific energy of any non
fissionable material and it produces over 3 times the amount of energy as an
equal weight of gasoline and when burned or is converted to electricity in a
fuel cell and water is the only by-product.
Hydrogen’s drawbacks are the
energy required to compress it to the 350 to 700 bar (atmospheres) needed for
volume and range considerations in most transportation applications and the CO2
produced by steam reforming of natural gas, which is the principal way the gas
is produced commercially.
Steam reforming is used because
electrolysis is between 3 and 10 times more costly but the CO2 negates much of
the environmental potential of hydrogen when both are produced by this process.
High-pressure electrolysis is the
cheapest form of electrolysis because it eliminates the need for further
compression of the gas.
At 1000 meters, the deepest extent
of a heat pipe OTEC system, the water pressure is 100 bar and electrolysis
performed there would bring hydrogen to the surface at that pressure.
Producing hydrogen this way buys
time to avoid climate catastrophe as the world transitions from fossil fuels to
zero emitting energy and is the best rationale for moving to a hydrogen economy,
with no emissions.
If climate catastrophe is
imminent, we should be prepared to address the problem regardless of the cost.
That is the primal human response to existential threats but since this is one
of the cheapest ways to produce zero emissions energy with high capacity we
should be transitioned to it on that basis alone.
According to a
recent survey, 77 percent of Canadians believe hydrogen is the "wave of the
Surely it is time to catch that