Duke Energy
has determined
that solar power
on the electric grid
results in increased
emissions of
real air pollution
-- nitrogen oxide,
or NOx, from natural
gas powered plants.
When solar power usage
is increased on the grid,
it's necessary for
natural gas power plants
to throttle back and
operate less efficiently,
with more pollutiony.
Natural gas
power plants
have to scale back
in the morning,
as the sun rises,
and then rapidly
increase output
in the evening,
when the sun sets.
Even when solar power
is at its maximum output,
during a sunny day,
more NOx pollution
is released than having
a 100% natural gas
powered electric grid.
Even worse are
partly cloudy days.
Solar power
is intermittent
on cloudy days,
so backup natural
gas power plants
must throttle up,
and throttle down,
repeatedly, during
the day, which results in
greater inefficiencies,
and even more NOx
emissions.
Duke said, that without
any solar power in the mix,
“a typical combined cycle
combustion turbine
emits NOx at
approximately
9-11 lb/hr,
assuming 24 hours of
‘normal’ operation,
and that is equivalent
to 264 pounds of NOx
emissions daily.”
Based on information
provided by Duke,
NOx emissions increase
to 624 pounds per day
when those same plants
ran with solar power
on the grid.
Duke Energy is working
on ways to reduce
the NOx gap, between
a grid using solar energy,
versus an electric grid
using NO solar energy.