H₂Go began in 1999 as an enabler for the hydrogen economy. Sorting through investment targets at the time, it was quickly determined that for hydrogen to become a feasible path as an energy carrier, electricity would need to be essentially free. As wind energy has dropped in price to a fantastic $1 per Watt, installed in the North Sea no less, we turned to solar as the next challenge. Today the average installed cost of classic flat panel solar is on the order of $6 per Watt. H₂Go is focused on bringing this cost down in dramatic fashion...

The Promise of Cheap Clean Energy Renewable energy has far more promise than commonly believed. Emerging technologies and the rampant run-up in energy costs have combined to make the development of these renewable sources far more appealing. The fact that they further benefit us through the reduction of pollution and dependency on foreign resources makes for a clear win:win situation. The Solar Allure If you were to view the planet from the perspective of renewable energy sources; wind, solar, and hydroelectric (wave and all other forms of renewable energy excluded for the moment, please forgive our simplification here), you will quickly find that where hydro is so plentiful, solar is not, where solar is abundant, wind is not, and so on. A pattern soon emerges to suggest that perhaps, our energy needs were met naturally all along. If you map this further, and add population distribution, you will discover that much of the best solar locations coincide with the highest population densities.

Technology Selection is Critical

Our solar journey began and remains with concentrator photovoltaic (CPV) designs. Thermal voltaic and steam, or other heat-generated electricity approaches, were all found to be inefficient or unreliable after thorough investigation and as we performed forensic analysis of failed companies. CPV designs replace the large number of silicon wafers employed in single-sun flat panel PV designs with concentrating or focusing mirrors and/or lenses which concentrate the sun’s energy, expressed as numbers of suns, onto small specialized solar cells. The sun, interestingly enough, provides close to 1,000 Watts of energy in a single square meter on the Earth’s surface. This energy refers to direct sunlight, that which is not diffused by cloud or precipitation. For our purposes, the particulates in the air from pollution, pollen, and other sources do not significantly degrade (yet) this handy formula. This direct sunlight can only be captured through the employ of a tracking system, keeping the sun firmly centered in the optics, much like a modern telescope.

The use of a lens to collect and focus the sun was thoroughly investigated but ruled out for both cost and reliability concerns. The most common Fresnel lens suffers from a limitation in maximum concentration, material deformation and degradation, and cost issues. Other forms of lenses suffered from weight or cost barriers for any practical application.

The first serious consideration for H₂Go was a clever 12m² line focus concentrator invented by Doug Woods. This system is capable of concentrating up to 2,000 suns onto a small rectangular focus at the receiver where the cells would be mounted. The tremendous energy thus focused necessitated a reliable liquid cooling scheme for the solar cells and this additional complexity was viewed as an additional opportunity for failure. Further, the high intensity solar flux posed a hazard of both fire and injury. Finally, the cells we hoped to use, at a concentration of 2,000 suns, had not been developed beyond the laboratory and they appeared susceptible to thermal cycling failure.

Breakthroughs in both non-imagining optical design and in triple-junction solar cells are the key enablers for H₂Go. Professors Jeffrey Gordon and Daniel Feuermann of Ben-Gurion University in Israel developed the mini-dish approach we adopted. The National Renewable Energy Laboratory (NREL) in Golden, Colorado provided the genius which became the most efficient cell design in the world. Jerry Olson, with Sarah Kurtz and
Alan Kibbler are due far more credit than they receive for this breakthrough development. A key licensee of this technology, Spectrolab, has fine-tuned the process and commercialized this design to provide an astounding conversion efficiency of 37% at the 500 sun intensity of our system. This is in contrast to 8 – 11% efficiencies of typical flat panel solar.

Teaming With the Best

H₂Go has teamed with UC Merced in a research agreement and with Ben-Gurion University to gain their invaluable assistance and collaboration toward our efforts. Professor Gordon, with Professors Roland Winston and Daniel Feuermann, joined to develop an extremely compact compound non-imaging optical design which we employ in our first generation systems. We will expand our collaborations and investment in further universities as well as government research labs globally throughout 2005. We believe that we can only afford the very best. Our close working relationship with these organizations provides a mutually beneficial and cost effective manner to both further our designs as well as to publish leading research and attract a world class team.

Process is paramount at H₂Go. Throughout our research and development we have relied heavily upon advanced CAD, finite element analysis, ray tracing, thermal analysis, accelerated aging tools and equipment. Yet our best results come about by remembering the quality adage:
There is always time to do it right the second time . This encourages us to delve deeply into all prior work published or patented in order to learn from the mistakes of others lest we repeat them ourselves. This approach has the envious advantage of saving countless dollars, not to mention lost time.

In September 2004, H₂Go held a comprehensive technical design and cost model review of our first generation design. Scientists, engineers, professors, CEO’s, and industry veterans assembled to review and critique our approaches to virtually every aspect of the system. While areas of concern voiced were relatively few, every opportunity for improvement was seized upon.

Next Steps

At the beginning of 2005, a total of six prototypes, of varying configurations between 500 and 2,000 Watts peak, are currently in the final stages of development. H₂Go will install these first systems at various research sites to gain the best possible performance knowledge in the shortest period of time, and by calling upon extraordinary people with unique skills. These sites include our headquarters in Saratoga, CA, NREL in Golden, Colorado, The Natural Energy Lab Hawaii in Kona, Ben-Gurion University in Israel, and at the University of California, Merced. As these systems begin to produce power and meet our performance targets, we will next begin to install a total of 2 MW at carefully chosen commercial locations. These early installations will serve to provide us with significant statistical data to begin characterization of all aspects of the design.

With the breakthrough optical and solar cell technologies in hand, H₂Go is now exploiting this technology toward providing solar energy that is cost competitive with modern combined cycle gas turbine power plants. Other critical factors we have focused upon are manufacturability, reliability, and maintenance costs. We must compete with classic energy as a commodity, not as a subsidized curiosity. Our overall cost model supports a cost per kWh of pennies when amortized over just ten years. The useful lifetime of each system is targeted for 75% of initial peak power output after twenty years of use.

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