Just as climate change is a
man made problem, the conditions
that brought about the waming hiatus can be replicated with technology that uses
heat pipes (Figure 1) to move surface ocean heat to deep water.
The oceans are
storing about 93 percent of the energy of climate change. When water is heated
it becomes less dense and rises thus the oceans are increasingly thermally
stratified. This stratification presents the opportunity to create work in
accordance with the 2nd law of thermodynamics.
The 2nd law
dictates that heat flows from warm to cold. When this flow is through a heat
engine (Figure 2) work is produced.
Heat pipes are
sometimes described as thermal superconductors because they rapidly move heat
through phase changes of a working fluid. They are a highly efficient way of
conducting heat away from a region where it can do harm, as with the ocean's
surface. The heat pipe’s efficiency stems from the fact they have no moving
parts yet they can transport heat at speeds approaching that of sound. They can
move heat counter to the forces of gravity and when a turbine is situated in the
vapor stream heat can be converted to work.
With enough of
these devices the hiatus can be perpetuated while generating as much energy as
is currently derived from fossil fuels.
Researchers from
the
University of Hawaii have estimated the oceans have the potential to produce
14 terawatts of energy this way - more than is derived from all of the world's
fossil fuels - with ocean thermal energy conversion or OTEC.
The efficiency of
this process is determined by the difference in absolute temperatures between
the warm and cold heat sink.
OTEC systems
only operate where surface temperatures are at least 20oC above the 4oC
found almost universally in the oceans at a depth of 1000 meters.
The theoretical efficiency of these systems is about
7 percent but
realistically about 5 percent is the best that can
be expected so 20 times more heat is moved through the heat engine than the
energy produced.
What engineers perceive as a drawback to these
systems is an environmental benefit in view of the recent finding that heat movement
into the depths means a slower increase in atmospheric warming.
For every kilowatt of energy produced with these
systems a 20 kilowatt (2000 percent) environmental heat benefit is
derived.
Scaling to the 14
terawatt maximum it is estimated the oceans can produce this way, 280 kilowatts of heat
is moved to the ocean
depths, which takes care of 89 percent of the 330 terawatts of heat/year
NOAA determined in 2010 the oceans are taking up on
account of global warming.
No amount of new
technology will magically solve the climate problem or even help much," unless
there's broad consensus on the need for urgent action, says Harvard physicist
David Keith.
By the same token,
unless climate
change is addressed in accordance with sound scientific principles the money
spent nominally to address the problem would be wasted.
