Instead of buying lump or briquette charcoal every time, can I just burn some birch and use that as the heat for my charcoal bbq?
You should be able to cook on your grill using various types of wood such as hickory, mesquite, cherry, maple, apple, etc. Per Recipetips.com , birch can be used also.
Birch - A softer wood, Birch is best used when grilling or smoking cuts of pork and poultry, providing a flavor similar to some varieties of maple.
Birch is a softer wood and can also be syrupy. Also hard woods cook longer than soft woods. Be sure to use large chunks rather than chips or small pieces. Just keep these things in mind when cooking with birch.
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.
I use wood all the time (including birch). Size and type will depend on what I am trying to do. For a slow smoke I will use a slow burning hardwood for coals and add small pieces of fruitwood or Hickory on the coals for flavour. If I am needing a quick hot fire birch with no bark works good. The bark normally comes off easily after it’s been seasoned in the wood pile. The bark creates all the dirt smoke and bitterness.
Wood is fine it is just a lot less practical. Wood takes a fair while longer to make coals and is not entirely as hot as charcoal. That being said it does stay longer so if you want a more gentle longer lasting fire it may be better.
Charcoal is in essence just half burned compressed wood anyway so you are not loosing anything substantial by just using regular wood.