Simon:
You can run spark ignited engines with 100% woodgas and diesel engines with up to 80% woodgas. Electric generator sets are my favored thing to power because a good genset can reduce down the size of your battery bank you need and save you some cash. A great thing to pair with your
solar power system.
Wayne Keith and Vesa Mikkonen are experts on running vehicles. See:
www.ekomobiili.fi/Tekstit/english_etusivu.htm
www.driveonwood.com
There is some power loss (30-50%) from woodgas as opposed to gasoline and they overcome it by using vehicles that are light with big engines.
I wouldn't use a big gasifier for your cookstove because it makes so much gas. If you meter the flow down too much the temperatures inside cool and you will start to let unburned oils into your gas stream. Not a big deal for heating applications, but no good if you want to fuel internal combustion engines. They need tar free gas.
In fact you shouldn't cook inside with the gas because there is no smell added and there is some
carbon monoxide in the gas. Its part of the fuel and balances the hydrogen giving an effective octane rating of about 104. Woodgas does well in high compression engines. Google "Mukunda Gasifier" for info on that.
I think the best use is to make electricity and harness waste heat for home heating and
greenhouse heating. Next up I would definitely want a gasifier powered
tractor and farm truck so you can keep vital supplies moving. Or if you don't want gasifier powered vehicles, then alcohol is an under rated fuel if you have a sugar source.
Thanks for your question,
Ben