I first wrote about Sundrop Fuels back in March 2010 for MIT Technology Review. At the time, the company’s focus was a system, based on solar concentrating technology, that would use the sun’s intense heat (up to 1,300 degrees C) to instantly vaporize biomass feedstocks, creating a syngas that could be used to make ethanol, methanol or gasoline. A key component of the company’s technology came from the University of Colorado, Boulder, and its spinoff company Copernican Energy, which Sundrop acquired in 2008. At the time, Colorado U chemical engineering professor Alan Weimer told me the process could become quite economical. “I can tell you the economics have been looked at pretty extensively, and the idea of being able to produce gasoline at less than $2 without any subsidies, we believe that is a real number,” he told me. He said the company’s syngas was very high quality and its process extracts more energy per unit weight of biomass than any other approach on the market.

Earlier this week Sundrop announced a major strategic investor, shale-gas developer Chesapeake Energy, which through its venture capital arm is investing $155 million in the company to help it begin construction of a commercial demonstration facility. Another $20 million will come from existing investor Oak Investment Partners. Sundrop’s commercial facility is expected to break ground in 2012 and will produce more than 40 million gallons of transportation fuel — i.e. drop-in biofuel — annually. It will be a fully integrated biorefinery, meaning its reactor technology will produce syngas that will be converted to methanol and then, using ExxonMobil’s patented methanol-to-gasoline process, will be turned into “green” gasoline. By 2016, the company hopes to have a 200-million gallon per year biorefinery up and running.

All good, except it seems Sundrop’s earlier focus on solar — as its name implies — seems to have been dropped. Not that solar isn’t part of the equation, but it’s no longer the key innovation being put front and centre. Indeed, the word “solar” doesn’t even appear in the Chesapeake press release. What’s used instead is “radiant particle technology,” meaning the company isn’t relying on solar as the main source of its heat. Sundrop Fuels’ own website makes that clear: “We can use clean-burning natural gas, electricity or even concentrated solar to power the RP Reactor, which by maintaining ultra-high temperatures to drive the endothermic gasification reaction ensures the most efficient use of biomass feedstock.”

Or even concentrated solar? I rest my case. From Sundrop to Sun Drop.

So this is basically a biomass play, not a solar play. Earlier, it could have been both. Actually, even the biomass portion is getting watered down. As Chesapeake says in its press release, “Sundrop Fuels is able to maximize its synthesis gas production by integrating clean, abundant natural gas with biomass feedstock, facilitating the most efficient utilization of hydrogen from both the biomass and natural gas to produce higher yields than any other biomass process.” That is, the company wants to mix biomass and natural gas together. What this tells me is that it’s most interested in the final refining process, which turns natural gas or syngas or a mix of both into “green” gasoline. “This investment is a key element of Chesapeake’s strategy to reduce U.S. dependence on OPEC oil imports by facilitating the production of tank-ready fuels from American natural gas,” according to the company. In other words, this is a natural gas-to-liquids play that can accommodate some biomass and solar.

Maybe this is the way to go — a foot in the door for renewables is better than no open door at all. Whether we’ll see the potential of this technology truly realized, that’s another question. But let’s make this clear: gasoline made from natural gas is not green, though it may be a little cleaner. If biomass and solar come to dominate the process, that’s a different ball game.