By Andrea Lang, Energy Fellow
Science is trying to remedy one
of the most often cited downsides of solar photovoltaic energy, its
intermittence. That is, solar panels do not generate energy at night, and
operate less efficiently in rain, fog, or cloudy weather. This intermittence can lead to significant problems for grid operators trying to balance production and demand, because
as
solar output drops off, more traditional sources of energy must quickly “ramp
up” production to compensate for that loss of electricity production. Since it
takes time for fossil fuel-fired plants to ramp up that production, grid
operators have a hard time meeting demand if too much solar production drops
off at one time due to weather or time of day.
But, if there’s one thing science
teaches us, it’s that just because something is a problem now doesn’t mean it
always will be. And happily, scientists are already hard at work and making
progress to address these issues with solar energy. Here are just a few of the
extremely useful (not to mention nifty) projects scientists and engineers are
working on right now that will hopefully lead to consistent, constant, and
–most importantly–renewable solar photovoltaic energy.
Graphene Solar Panels: Rain or Shine
Widely reported last week, Chinese engineers announced
that they are working on a way to generate electricity from rain that falls on
solar panels by using graphene, a two-dimensional sheet of carbon molecules
arranged in a honeycomb pattern (pictured right). Graphene has very high
conductivity, resulting in a large amount of electrons flowing across its
surface. The researchers propose to take advantage of the positive ions present
in trace amounts of salt in rainwater, which form a double layer with the
graphene electrons. The difference in electrical potential between those two
layers (the positive ions from the rainwater and the electrons flowing through
the graphene), with the water in between, creates a type of “pseudo-capacitor”
which can generate electricity.
In addition to this recent
development of generating electricity from rain using graphene, the material
also has long been thought to be the key to making solar panels more efficient. The main
trouble with graphene is that it’s been inefficient (and therefore expensive) to produce
in large quantities. However, just as the technologies to apply graphene are
evolving, so is the technology to mass-produce it. Scientists at the Massachusetts Institute of Technology announced improvements
in graphene production technology last summer. Although these technologies are in
the development phase, they represent a promising start in terms of generating
electricity from solar panels, rain or shine.
Space-Based Solar Power: Night or Day
On Earth, night always rolls
around eventually and eliminates electricity generation from solar panels. But
space doesn’t have that constraint. That’s why scientists have been exploring the possibility
of collecting solar energy in space and literally “beaming” it down to Earth.
Space-based solar collection
would work by launching solar collectors into low orbit, and then using either
laser or microwave beams to transmit that energy back down to Earth, where it
would be collected and added to the grid.
However, space-based solar
collectors are likely to be very expensive. Not only do scientists have to
perfect the technology to make them work, they have to develop the technology
and spend the money to launch them into space. According to the Department of Energy, it would cost in the tens of billions of dollars to
assemble, launch, and operate a solar collecting and beaming satellite.
However, if the technology can be
made cost-effective, space-based solar energy has other benefits besides the
ability to collect solar energy day or night. First, a significant amount of
solar energy is lost by the time the sun’s rays penetrate Earth’s atmosphere
and hit land-based solar panels, even when it isn’t a cloudy day. By collecting
that energy before it is lost in the atmosphere, space-based solar energy
collection would be much more efficient. Second, land-based solar collectors,
especially utility-scale arrays, occasionally come into conflict with aesthetic, natural or cultural resources. Space, though,
is literally wide-open, so space-based solar collectors won’t have to compete with
other valuable resources.
As these exciting new
technologies continue to develop, the potential is clearly there to overcome
the obstacles posed by widespread solar deployment. These are just two examples
of many technologies in development that can help solar energy become more
efficient, constant, and reliable.
