Just because promises don’t happen in 2010 doesn’t mean they won’t happen ever. But, for what it’s worth, here are 10 of the most interesting developments in our estimation to watch for in 2010, in no particular order:

1. EEStor’s ultracapacitors: 2010 is thought to be the make-it-or-break-it year for the partnership between Toronto-based electric vehicle maker Zenn Motor and super-stealthy EEStor. At last count, Texas-based EEStor promised to deliver its potentially breakthrough ultracapacitors to Zenn before the end of 2009. ...

2. Big win for desalination: Poseidon Resources plans to begin construction in the first quarter of next year on a desalination facility to process 50 million gallons of seawater per day in Carlsbad, Calif. The ground-breaking is a long time coming for Poseidon, which faced delays of more than 10 years because of added scrutiny and lawsuits by environmental groups. ...

3. Ambitious targets: California’s Renewable Portfolio Standard calls for 20 percent energy demand to come from renewables by 2010. The state’s two big utilities have already said this isn’t likely to happen. As of November, Pacific Gas & Electric was getting 13 percent from renewables, while San Diego Gas & Electric gets only about 10 percent of its energy from renewables. The next big target is 33 percent by 2020.

4. Japan’s new EV infrastructure: Shai Agassi’s startup Better Place aims to install its first battery swapping station in Tokyo in January, a preview of what’s being developed in Denmark and Israel for mass deployment in 2011 (see Better Place’s battery-swap stations for Tokyo taxis get investor approval). ...

5. Greener bricks: Just as Serious Materials is aiming to overhaul the energy-intensive drywall industry, Newark, Calif.-based CalStar Products wants to improve brick-making. The startup expects is first factory for low-carbon bricks in Caledonia, Wis., to begin full-scale manufacturing in January. ...

6. Space solar: Solaren might be the best-known startup in this space, but its contract with Pacific Gas & Electric doesn’t start until mid-June 2016. Everett, Wash.-based PowerSat has more immediate plans: It wants to build a 10-kilowatt Earth-based demonstration project early next year. ...

7. Baby steps for cellulosic ethanol and biofuel: Watch for a number of biofuel developers to announce the opening or ground-breaking at new facilities in 2010. Range Fuels said it plans to complete a 10 million-gallons-per-year ethanol and methanol plant in Soperton, Ga., in the first quarter of 2010, with volume production to begin in Q2. LS9 plans to develop a demonstration facility in the first quarter of 2010, with production slated for that year using a tank of 50,000 to 100,000 liters. ...

8. Large-scale solar: Tempe, Ariz.-based First Solar says it expects development for the $1 billion, 550-MW thin-film solar plant under a power-purchase agreement with California utility Pacific Gas & Electric to begin on-schedule in 2010. First Solar bought the development rights from OptiSolar (see First Solar buys OptiSolar's pipeline of projects for $400M).

9. Big auto embraces electric: 2010 is expected to see the debut of two hotly anticipated electric vehicles in the U.S. market. The latest word on the Chevrolet Volt, which is supposed to drive up to 40 miles without gasoline, is that production could start in late 2010 ...

10. Small auto gets up to speed: Irvine, Calif.-based Fisker Automotive said its $87,900 luxury sports sedan Karma is due in showrooms in summer 2010 (see $529M DOE loan clears path for Fisker's new $39,000 hybrid), while Norway’s Think Global said it plans to produce 2,500 cars in the U.S. starting in mid-2010, about a year later than first anticipated ...