Photosynthesis-like
technologies offer a sustainable future even as world populations grow by
generating and storing the energy to run homes and cars on-site, according to
the inventor of a new renewable personal energy system at the Massachusetts
Institute of Technology.
Personal
energy (PE) is the goal of professor Daniel Nocera, director of both the Solar
Revolutions Project and the Eni Solar Frontiers Center at MIT. According to Nocera, PE systems emulate the way a plant
transforms solar energy into a fuel that can be used at night and on cloudy
days. PE aims to enable a renewable, sustainable future, even as the world's
energy needs double by 2050.
PE works by
creating a self-contained energy generation and storage system at its
point-of-use location. As the world population grows by another 3 billion by
2050, demand for energy can nevertheless be kept carbon-neutral by adopting a
PE model for energy generation, as opposed to the centralized energy generation
and distribution grids used today. PE generates electricity with solar panels
during sunny days that is stored as liquid fuel on-site, then converted into
electricity by fuel cells that are drawn upon at night to power homes and recharge
plug-in hybrid vehicles.
According
to Nocera's new report titled "Chemistry of
Personalized Solar Energy," rival methods of storing solar
energy do not offer high enough energy density to realize PE, including current
proposals by others to use compressed air, flywheels, super-capacitors, pumped
water and batteries.
Battery technology is advancing with regard
to increased lifetime and power density—the rate at which a charge can flow in
and out of the battery. However, Nocera claims that the needed energy density—the
amount of energy stored per unit volume—required to realize PE can only be met
by storing energy in liquid fuels during the day at their point of use, the way
a plant does using photosynthesis.
Key to
success of such a system is the efficiency of a photosynthesis-like method of
splitting water molecules into oxygen and hydrogen that can be stored in
separate tanks, then recombined by a fuel cell to provide electricity to the
home and car when sunlight is not available.
According
to the report, a deeper understanding of the water-splitting catalysts that
emulate photosynthesis has been sought by chemists over the last several
decades. Nocera claims his team has now discovered a cobalt-based catalyst that
realizes this dream for the first time. Using his cobalt-based catalysts
provides a manufacturable, efficient and inexpensive method of splitting water
into hydrogen and oxygen for PE.
By
emulating the functional elements of photosynthesis, Nocera's
team is currently working toward realizing the potential of personal
energy systems for creating a renewable, sustainable future.
