Is wood a good alternative to charcoal for bbq fuel?
You can use any non-poisonous wood you like.

Every wood has a different heat and smoke profile. "Soft woods" like birch will generally burn very hot for a short time, so OK for sausages, small meat cuts, and small vegetables, but not so good for large meat cuts, roasts, or for BBQ'ing covered for the full smoke effect as you will most likely need to re-stock the fire every 20 or 30 minutes.

Most people let the wood burn off the main smoke (which usually doesn't taste too good), and BBQ on the red/white embers. The wood stage is now similar to charcoal, but a lot more smokey, which is great if you like smoke.

For sausages, small cuts and small vegetables, hardwood is basically wasted, as they will cook in ten minutes, and the hardwood has 20 to 30+ minutes of burn time in it.

You can BBQ small stuff using a few handfuls of dry twigs or even driftwood if you want too. Twigs from fruit trees or lavender bushes make great smoke!

We always travel with a small lidded BBQ (metal box 60x40x40 cm with vent holes on sides), we use a handful or two of driftwood, once the smoke dies down, add a few peppered steaks, pre-cooked potatoes, oiled asparagus, soaked corn on the cob. Put the lid on, and come back in 15 to 20 minutes, smokey slow cooked heaven.