Also in use since the 80's in various African countries... http://www.songhai.org/index.php/en/home-en/16-songhai/190-bioenergie-en http://www.songhai.org/index

Also in use since the 80's in various African countries... http://www.songhai.org/index.php/en/home-en/16-songhai/190-bioenergie-en http://www.songhai.org/index.php/en/home-en/16-songhai/190-b... The Songhai Center does a full carbon cycle re-use. An interesting place to visit too!