It's been a while since I blogged, mainly because for the past week and a half I was in Colorado on a research trip for my book on renewable energy. I met with scientists and researchers and entrepreneurs of all stripes--at the Rocky Mountain Institute, the National Renewable Energy Lab (NREL), University of Colorado, Colorado State, Sundrop Biofuels, Solix (an algae biofuel company), and many others.

I learned a lot about wind and solar and biofuels and hydrogen and all the other key players in the world of renewables. But probably the key takeaway message was one of convergence. As one researcher put it, "when it comes to renewables, there's no silver bullet, just a bunch of bee-bees." And many of those bee-bees, I learned, are starting to be packaged together.

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A few examples:

SunDrop Biofuels, a spinoff company founded by Al Wiemer at CU Boulder, combines solar power and biofuel gassification technology. Hundreds of mirrors reflect sunlight onto a large, heat-absorbing metal sheet mounted on a tower. The heat--topping out around 1200 degrees C--is used to initiate a chemical reaction that turns woodchips and other biomass into a gas that can then be refined into gasoline or diesel.

At the National Wind Technology Center, I met with NREL researcher Kevin Harrison, who runs NREL's "Wind to Hydrogen" project. It basically involves using wind (and solar) to generate electricity used to spit water into hydrogen and oxygen. The hydrogen is stored and used to power a fuel cell to create electricity or to run an internal combustion engine.

Finally, I met with NREL scientist Terry Penney, who showed me a PowerPoint presentation about how electric cars could function as mobile power stations and energy-storage units. 

In short, I left Denver with a new appreciation for how well many renewable technologies already work, how far we still have to go to get to a point where renewables are ready to take a serious bite out of fossil fuel's market share, and how whenever that happens, it will be due in large part to the convergence of renewable energy technologies.

I've posted lots of pictures (with captions) on my book blog: Renewable.