Hi all,
Here in Spain where I live, we are surrounded by thousands and thousands of almond and olive trees. All the 'fruits' are taken to food processing plants and the almond shells and the olive stones are sold on to the local residents for the winter heating...Tis cold up here in the mountains....They give of very good heat , between 10 and 15 k ,but need a lot of space to store the fuel. These types of stove need a big hopper, but they do dry the 'fuel' before it drops to the burner below. Very efficient, very clean and cheap. The stoves are made locally and they cost about 100 Euro or £80 ish...
Tony