Simple Shunt Voltage Limiter
As requested in your comment ...

Don't do that, unless your LED D2 can handle all the current that you need to sink to keep your voltage down, regardless of what current you throw at it.

If LED D2 is a standard 5mm LED, they are probably good to 20mA. Most small zeners would take that, and more, before letting out the magic smoke. 

Perhaps put the LED in series with a lower voltage zener diode (LEDs have a pretty steep V/I function, often steeper than zeners!), and connect Q1 collector directly to rail. This will mean then that the LED has to only conduct 1/beta of the current being sunk. Bipolar transistors can be had that will sink amps and dissipate 10s of watts, with adequate heatsinking. To make the LED shine adequately, connect a resistor in parallel with C1, to sink a certain current at the 0.7v needed to turn on Q1, this will ensure the LED gets enough current to light when the circuit is limiting.