Sunlight in a Tank
The 2007 Conference That Fought for Our Energy Future
In 2007, a group of brilliant minds gathered to tackle one of humanity's greatest challenges: harnessing the power of the sun to create a sustainable future.
The Energy Grand Challenge
Imagine a power source so abundant that it delivers more energy to the Earth in a single hour than humanity consumes from fossil fuels in an entire year. This is not science fiction—this is the reality of solar energy1 . Yet, for all its abundance, sunlight presents a formidable challenge: it is intermittent, disappearing at night and on cloudy days. The critical question that brought scientists together at the 2007 Renewable Energy: Solar Fuels Gordon Research Conference was straightforward yet profound: How can we efficiently capture and store solar energy for use when and where we need it?1
Held from January 21-26 in Ventura, California, this inaugural conference was born from a sobering realization. Fossil fuels supplied—and still supply—about 90% of the energy consumed by industrialized nations1 .
With energy consumption projected to more than double by 2050, our existing model is not sustainable. The conference chair, Daniel G. Nocera from MIT, opened the event with a clear mission: to address "the outstanding technical problem of the 21st Century - the efficient, and ultimately economical, storage of energy from carbon-neutral sources"1 . This was not merely an academic gathering; it was a strategic convening of leading chemists, physicists, materials scientists, and biologists to forge a partnership of knowledge essential for a renewable energy revolution3 .
Date: January 21-26, 2007
Location: Ventura, California
Focus: Solar Fuels & Renewable Energy
Chair: Daniel G. Nocera (MIT)
Learning from a Billion-Year-Old Master: Natural Photosynthesis
A central theme of the conference was the quest to emulate and improve upon nature's own solar energy system: photosynthesis. For billions of years, plants and certain bacteria have been using sunlight to split water and create energy-rich molecules. Understanding this biological machinery was a key focus.
Jim Barber - Imperial College London
Presented work on unraveling how nature's photosystem II efficiently splits water into oxygen, protons, and electrons1 .
Maria Ghirardi - National Renewable Energy Laboratory
Explored the fascinating world of [FeFe]-hydrogenases, a class of enzymes in green algae that can produce hydrogen gas with remarkable efficiency1 .
These biological catalysts served as a blueprint, showing scientists the fundamental principles of activating small molecules like water using energy from light.
Nature's Solar Energy System
Plants have perfected solar energy conversion over billions of years of evolution. The conference aimed to understand and replicate these natural processes.
The Artificial Leaf: Mimicking Nature with Human Ingenuity
Inspired by nature but not limited by it, researchers presented groundbreaking work on building artificial systems. The goal of artificial photosynthesis is to create a cost-effective and durable "artificial leaf" that can use sunlight to produce fuels such as hydrogen or hydrocarbons.
Thomas Moore from Arizona State University discussed the integration of technology with biology for efficient solar energy conversion1 .
His work, and that of others, focused on the core components of such a system:
- Light Absorbers: Materials that capture photons, much like chlorophyll in plants.
- Catalysts: Substances that drive the key chemical reactions—splitting water (H₂O) into hydrogen (H₂) and oxygen (O₂), and reducing carbon dioxide (CO₂) into fuels.
- Integration: The monumental challenge of assembling these components into a functional, efficient, and scalable device.
The conference highlighted the daunting efficiency target: a 10 to 50-fold decrease in the cost-to-efficiency ratio for producing stored fuels. The ultimate aim was to reduce the cost of installed solar energy conversion systems to a mere $0.20 per peak watt, a price that would make solar fuels economically competitive with fossil fuels1 .
Light Absorbers 40%
Catalysts 25%
Integration 15%
Cost Reduction 20%
10-50x
Decrease in cost-to-efficiency ratio needed
$0.20
Target cost per peak watt
A Deep Dive into [FeFe]-Hydrogenase Experimentation
Much of the excitement at the conference revolved around harnessing biological principles for human-made technology. A prime example was the work on hydrogenases, enzymes that cleanly and efficiently produce hydrogen gas. Let's explore a typical experiment that a researcher like Maria Ghirardi might have presented, aiming to understand and utilize these biological catalysts1 .
The experimental process to study and apply hydrogenases involves several meticulous steps:
- Enzyme Isolation: The [FeFe]-hydrogenase enzyme is carefully extracted and purified from green algae or bacteria, ensuring it remains in its active, functional state.
- Electrode Functionalization: A carbon-based electrode is prepared and modified with specific chemical linkers that can "wire" the enzyme to the electrical circuit.
- Immobilization: The purified hydrogenase enzyme is attached to the functionalized electrode, creating a biohybrid electrode.
- Electrochemical Testing: The biohybrid electrode is placed in a buffered aqueous solution, and a controlled electrical potential is applied to drive the reaction.
- Gas Measurement: The hydrogen gas produced at the electrode is quantified in real-time using a sensitive detector, such as a gas chromatograph.
The core results from such experiments reveal why hydrogenases captured the imagination of scientists at the conference. The table below summarizes the performance of a [FeFe]-hydrogenase compared to a common human-made catalyst, Platinum:
| Catalyst | Turnover Frequency (TOF) | Overpotential Required | Stability in Air |
|---|---|---|---|
| [FeFe]-Hydrogenase | Extremely High (~10,000 s⁻¹) | Very Low | Low (O₂-sensitive) |
| Platinum (Pt) | High (~1,000 s⁻¹) | Low | High (Robust) |
The data shows that the biological catalyst, [FeFe]-hydrogenase, operates with an extraordinarily high turnover frequency (TOF), meaning each enzyme molecule can produce hydrogen molecules at a rate far surpassing even the best human-made catalysts like platinum1 . Furthermore, it does this at a very low overpotential—the "push" or extra energy required to get a reaction started. This high efficiency at mild conditions is a hallmark of biological catalysis.
The trade-off, however, is stability. These sophisticated enzymes are often sensitive to oxygen and can be fragile outside their native environment1 . This fundamental insight drives a major branch of solar fuels research: either creating robust biohybrid systems that protect the enzyme or designing synthetic catalysts that mimic the active site of the enzyme without its inherent fragility. Fraser A. Armstrong's work at the University of Oxford on rapid electrocatalysis by hydrogenases was pivotal in demonstrating the practical potential and inspiring new synthetic approaches1 .
Catalyst Performance Comparison
Turnover Frequency (TOF) Comparison
Stability vs Efficiency Trade-off
The Scientist's Toolkit: Building Blocks for a Solar Future
The research discussed at the 2007 conference relied on a diverse arsenal of materials and chemicals. The following table outlines some of the key "research reagent solutions" essential for pioneering work in solar fuels.
| Reagent/Material | Primary Function | Application Example |
|---|---|---|
| Molecular Catalysts | Facilitate key reactions like water splitting or CO₂ reduction | Cobalt or nickel-based complexes for hydrogen evolution1 . |
| Semiconductor Materials | Absorb light to create electron-hole pairs that drive reactions | Metal oxides like TiO₂ or WO₃ used as photoanodes for water oxidation. |
| Electrolytes | Provide ionic conductivity within an electrochemical cell | Aqueous potassium phosphate buffer for bioelectrodes. |
| Metal-Organic Frameworks | Porous materials for gas storage or as catalytic platforms | MOFs for hydrogen storage, as discussed by Omar Yaghi1 . |
| Sensitizer Dyes | Capture a broad range of sunlight and transfer energy | Ruthenium polypyridyl complexes used in dye-sensitized solar cells. |
Molecular Catalysts
Designed to drive specific chemical reactions with high efficiency and selectivity.
Semiconductors
Light-absorbing materials that generate charge carriers when illuminated.
MOFs
Porous materials with high surface areas for gas storage and catalysis.
From a 2007 Seed, a Global Field Grows
The 2007 Gordon Research Conference on Renewable Energy: Solar Fuels was a catalytic event in itself. It provided a unique forum for sharing the foundational science needed to "permit future generations to use the sun as a renewable and sustainable primary energy source"1 . The discussions, spanning from global climate predictions by Richard Somerville to innovative hydrogen storage solutions by Omar Yaghi, set a vibrant research agenda1 .
The legacy of that inaugural meeting is profound. The conference has continued biennially, tracking the field's rapid acceleration2 . Research in solar fuels has expanded dramatically, moving from fundamental studies of catalysts and light absorbers to the development of integrated systems and pilot-scale devices. The vision laid out in 2007—to store solar energy in chemical bonds—continues to drive scientific innovation today, as seen in subsequent GRC themes like "Frontiers in Photon-Driven Fuel Production" in 20242 . The work presented all those years ago continues to illuminate the path toward a future powered by clean, sustainable, and abundant sunlight.
Field Expansion
Solar fuels research has grown exponentially since 2007
Global Collaboration
International research networks formed and strengthened
Continued Innovation
Biennial conferences continue to drive the field forward