There are three CNG refueling stations between home and work, 30miles. Not exactly "one on every corner", but the closest station is about 5 minutes from my house, actually on an onramp to the freeway I commute on.
To qualify for the HOV lane with a single occupant in CA, it must meet the requirements of ULEV AND ILEV. The ULEV requirement isn't difficult to achieve with gasoline, but the ILEV requirement ONLY allows electric, CNG, and LPG fuels. A dual fuel vehicle using gasoline would not qualify.
Here is a CARB website with some qualifying vehicles. One interesting vehicle included in the HOV exemption is the 5.4L CNG F-150. I see these driven by CalTrans sometimes. If someone would make a hybrid that ran on a CNG or LPG engine instead of gasoline, it would qualify for HOV.
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Additionally, a company called
FuelMaker makes a refueling station that can be residentially installed. I've heard they run about $4k, but they're trying to get the price down to $1k. Essentially, the natural gas is used to fuel my furnace and water heater here in CA. This refueling station will compress about one tank per day. So just plug it in at night and it refuels. Or maybe an employer could be convinced to install one and get a tax credit. Supposedly they're about as noisy as a pool pump, so if you have neighbors, an enclosure might be in order.