Energy research at Berkeley Lab
At Berkeley Lab, the energy challenge has captured the imagination
of some of our very best scientists. We are mounting a major, multidisciplinary
initiative to create sustainable, carbon-neutral sources of energy.
This effort seeks to understand the fundamental mechanisms in
organic and inorganic energy conversion that will serve as the
foundation for technology developments in the environmentally responsible
production and conversion of renewable resources for fuels, chemicals,
and other energy-enriched products. Berkeley Lab brings a unique
combination of research strengths to bear on the energy problem.
Helios: A new facility proposal for
solar energy research
A
future cornerstone of the Berkeley Lab energy initiative is The
Helios Project,
a new energy/nano research building that would be central to one
of our major scientific initiatives: The conversion of solar energy
into carbon-neutral form of energy that could sustain our world
in an environmentally friendly manner. Named after the Greek god
of the sun, Helios is poised to address one of the most
important societal problems that science and technology can help
solve. Berkeley Lab, with its broad spectrum of expertise
and its history of team collaborations, is ideally positioned to
address this challenge.
The Helios Project proposal, led by Laboratory Associate Director
Paul Alivisatos and Physical Biosciences Director Jay Keasling,
will cut across divisions and programs in profound ways to produce
transforming technologies in synthetic biology and nanotechnology,
and will fuse our core strengths in biological, chemical, and physical
sciences in the search for a sustainable carbon-neutral source
of energy. Now is the time to consider how new research
at the interface of basic energy sciences and applied fields
of energy technology can increase our future energy options. A
well-conceived program put in place now has the potential to provide
the people of the United States with renewable energy security
and economic growth in the decades to come.
Synthetic biology: Biologically inspired systems
for biomass-to-fuel and solar-to-chemical solutions
Biomass, mankind’s long-standing energy source, has the
potential of supplying
significant amounts of renewable energy if efficiencies for the
conversion to fuels can be
substantially improved. Corn-to-ethanol is perhaps the most touted
biomass energy solution, but it the current conversion process
actually consumes more fossil energy than it creates,
while creating substantial water and air pollution. Meanwhile,
cellulose, the largest available biomass, resource remains untapped.
A more direct photosynthetic biomass solution - direct solar hydrogen
from cyanobacteria and green algae - is currently limited by the
low light-to-fuel efficiency of these natural systems. To address
these problems, synthetic biologists are now looking at these research
areas:
- Engineering organisms to produce fertilizers on-site,
especially photosynthetic
nitrogen fixation in the form of ammonia. This will improve the
energy balance for corn
to fuel by avoiding the large fossil fuel consumption by conventional
manufacturing processes and fertilizer transportation. More sustainable
sources of phosphorous would have to be found.
- Engineering novel metabolic pathways for the conversion
of cellulose to fuel (ethanol, methanol, methane, hydrogen).
Possible approaches include
the design of an organism with an artificial chromosome that
incorporates the relevant
features of the cellulose degrading machinery.
- Engineering of green algae and cyanobacteria with improved
photosynthesis rates, and on-site
coupling of hydrogen production to catalytic conversion to carbon-based
fuels are important
targets.
- Biologically-inspired synthetic catalysts for key bond forming
and breaking steps for
fuel formation and interconversion of various forms of fuels.
Enhancement of the
stability and increase of the rates compared to natural catalysts
through synthetic
modification and use of nanostructured catalyst supports is an
important goal. Development of efficient methods for coupling
of catalysts to electron or hole source, and embedding in robust
nanostructured supports for enhanced stability are crucial tasks.
Engineered systems: Hybrid nanomaterials
and biomimetic systems for solar-to-fuel conversion
Artificial photosynthetic devices for solar-to-fuel
conversion offer the potential of robust and
efficient systems not limited by the constraints of living organisms.
Two major challenges need to be met in order to achieve this
goal. One area is biomimetic catalysts
that accomplish organism-like multi-electron transformations (such
as H2O oxidation to O2 or CO2 reduction to a carbon-based liquid
fuel) but at much higher, robust
rates compared to natural systems. Of the few existing engineered
catalysts that accomplish such transformations, some require noble
metals whose insufficient abundance precludes their use in a large
scale energy economy, and almost
all are driven by stoichiometric reagents rather than by visible
light. Progress is hindered
by a lack of understanding of the bond making/breaking steps and
coupled proton and
electron transfer events at catalytic sites. A second major challenge
is bio-inspired
supramolecular assemblies that afford optimum coupling of light-harvesting,
charge
migration, and catalytic components for efficient fuel formation.
With these two challenges in mind, Berkeley Lab scientists are
considering these primary research areas:
- Development of
synthetic catalysts with abundant low Z metals (Mn, Fe, Co, Ni,
Cu, Zn) for the splitting
of water, reduction of CO2 to formic acid and ultimately to methanol,
or for the formation
of halogens from hydrogen halides. Key aspects are multi-electron
transfer capability and control of proton and electron transfer,
the design of which will benefit greatly from insights gained
by structural and mechanistic studies of biological catalysts.
- Exploration
of methods for increasing the durability of biomimetic catalysts,
such as encapsulation or anchoring on inorganic supports and
establishing mechanisms for self repair.
- Exploration of organic or biological/organic 3-D hybrid
structures for integration and optimal organization of the photoactive
and catalytic moieties, taking architectural design principles
of nature as a guide.
- Exploration of light-driven
generation of ion gradients across membranes as a
solar energy storage mode that can be exploited in such bio-inspired
supramolecular assemblies, requiring the development
of synthetic proton pumps.
Nanomaterials and nanostructured assemblies
for photochemical conversion
(solar-to-electric and solar-to-fuel conversion)
The emergence of nanotechnology
and the rapid advances in the development of novel
nanoscale and nanostructured materials has opened up unprecedented
opportunities to
overcome long-standing obstacles toward efficient conversion of
solar light to electricity
and fuels. However, major obstacles include: the efficient
absorption of photons from the full solar
spectrum; the durability of light harvesting and fuel forming
sites, and of supports for the
vectorial arrangement of the various components; efficient
contacts between photoactive
charge-transfer components and catalytic sites; spatial separation
of the
chemical products generated at oxidizing and reducing sites to
prevent efficiencydegrading
back or cross reactions; and materials suitable for inexpensive
fabrication and
processing of solar to electric or solar to fuel assemblies on
a very large scale.
Berkeley Lab recognizes the need to launch a concerted effort
advance nanoscience and
technology in solving these challenges. In particular, novel approaches
by nanostructured
materials should be explored to control the fundamental processes
such as absorption of
light and the density of photon, electron and phonon states to
maximize the use of solar
radiation. New types of nanomaterials need to be engineered that
minimize the loss of
charge, particularly in the promising area of metal oxide and metal
sulfide semiconductor
systems. 3-D inorganic or organic/inorganic hybrid nanostructures
should be explored to
control the transport of chemicals in photosynthetic systems to
avoid loss by cross
reactions, and to achieve integration of the functional components
with precise
arrangement for optimal coupling. Such materials might offer strategies
that will enhance
robustness through recycling of degraded organic components during
operation.
Nanoscale engineering needs to be developed for improved charge
contacts at interfaces
and between surfaces and molecular components, including biological
functionalities on
inorganic supports. This is an important prerequisite for the integration
of multi-electron
transfer catalysts into nanoscale materials. Effort should focus
on exploiting
nanotechnology for designing solar to electric or fuel device fabrication
that resembles
plastic manufacturing.
Photoelectrochemistry
The lack of
efficient multi-electron
transfer catalysts for water oxidation and proton or CO2 reduction
is the single most
critical challenge of efficient photoelectrochemical fuels generation
(methanol, methane,
hydrogen). Whether considering photovoltaic coupled to electrochemical
devices or
photoactive electrodes of photoelectrochemical cells, the performance
of all existing
systems is limited by the inefficiency of the fuel forming transformations
at the
electrodes. There is a need for the design of engineered enzymes
that catalyze the above redox
reactions at the appropriate potential and at substantially higher
turnover rates compared
to natural catalysts. Another important engineering aspect is improved
stability over the
biological systems. The effort requires a close collaboration between
chemical biologists
and inorganic and materials chemists.
Berkeley Lab - a unique blend of research strengths
Led by Berkeley Lab Director Steve Chu's conviction that we can
and need to tackle this problem now, our unique combination
of strengths in many of these areas positions it to mount the kind
of large-scale, interdisciplinary research effort that the energy
problem calls for. Our hope is that some of the most rapidly advancing
areas in science, such as nanotechnology and synthetic
biology, will transform industries, enabled by world-class
facilities like Berkeley Lab's Molecular
Foundry, now under construction, and the new Berkeley
West Biocenter. Government and industry investment
-- as well as immense public support -- is needed to drive the
nationwide quest to secure our energy future.
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