Carina and I are developing a concept for a social enterprise: combining clearance of Rhododendron ponticum (using the lever and mulch method) with biochar production.
To this end we are buying a kin-tiki kiln from a smith in Northumberland. The plan is for it to be brought up to us early in August. Such kilns are good for making biochar. A few weeks ago we experimented with a small kiln and made some biochar at Ferry Wood.
Yesterday I did a pitch at a Dragons Den event organised by the Social Enterprise network, resulting in us getting help from local enterprise support organisation Inspiralba to develop the idea further.
The picture was taken in Northumberland and features the same kiln we have ordered from Fairley Forge.
bioregioning 
hi edward, did you progress this and what were the results. I’m trying something similar on my land on the west coast of Ireland and wondered whether you’re aware if there is any analysis of biochar made from rhododendrons i.e. is it benevolent to native plant growth?
Hi James. We add biochar to our compost and directly to the soil in our garden. It doesn’t do any harm but we have not got round to doing a proper trial on this. There should be data from the (now defunct) biochar research project at Edinburgh University but I have not hunted it out yet.