are commercial operations that crack
plastics in this way, but
their economic viability is limited by the costs of providing energy
(as heat) and hydrogen (usually in the form of acids).
It occurred to me that
this hydrogen could be generated through the
electrolysis of sea water, using electricity from solar or wave power. Electrolytic
cells that will do this already exist (this links to a PDF
The main byproducts of
producing hydrogen are either oxygen, which could be either collected
or released into the atmosphere, or chlorine, sodium
hydroxide and hypochlorite. Different
and cell conditions result in different products; it will undoubtedly
require some experimentation to get this just right.
Sodium hydroxide reacts
with carbon dioxide to produce carbonate, which
is alkaline, so adding this to the oceans will alleviate the
acidification of the
oceans caused by increasing carbon dioxide levels. The chlorine
produced (if any) will have to be stored (perhaps by chemically
"an aqueous solution containing about 1 to 400 g/l of iron(II) chloride
and at least one of copper (I) and copper(II) ions, the chlorine being
adsorbed with conversion of the iron(II) chloride into iron(III)
chloride" (United States Patent 4082631 ). Some plastics (for
example PVC) also produce chlorine when cracked, so we will need a way
of dealing with chlorine anyway, making the kind of electrolytic cell
that produces both chlorine and hydroxide more practical.
The heat required for the
plastics cracking process could also be
supplied by the sun: a parabolic mirror of the right size in a sunny
part of the world would be effective.
I can imagine two
different ways this might work.
The first would be a small
plant on a beach, perhaps on the Indian
Ocean, where waste plastics are continuously washed up. Local people
could supply the machine with plastics they picked up on the beach, and
machine could be set to produce hydrocarbons that would work as fuel
for whatever the favoured local mode of transport might be. Fractional
distillation using solar heat and seawater coolant should work.
Maintenance and repairs could also be carried out by trained local
The second would be a
floating drone plant, powered by solar energy,
gathering plastics from one of the several plastic
gyres in the oceans. It could also
produce and store hydrogen gas, again from the electrolysis of
seawater. Whether it would be feasible to have an unmanned plant
cracking plastics, given the high temperatures involved, I'm
not sure. Perhaps it would be better to just collect plastics and
hydrogen, and send out a radio beacon message to alert the owner that
it is full. The cracking process could then be carried out elsewhere.
Clearly there are several
aspects of this that need clarifying, and a
feasibility study needs to be done. Separating the polymers from other
material such as marine life and other garbage could be a problem, as
could disposing of any chlorine generated, but these are hopefully
My back-of-the envelope
calculations suggest that it could work. It would require a
considerable initial capital outlay, but running costs would be
minimal; cleaning, maintenance and repairs only. As oil prices
continue to rise, the viability of this type of operation will only
If you have any ideas as
to how I can get the right people interested
in this idea, please let me know - click the 'Contact' button at the
top right of the page.