Fuel pellets for pellet stoves and boilers are today almost exclusively made from wood. Its not that we cannot use thousands of different biomass materials to make pellets, its just the wood industry are the ones who have really driven the market up to now.
However the pellet fuel market is now developing to include using other biomass energy crops such as miscanthus, switchgrass and in this particularly case hemp, and hemp pellets. All of these biomass materials can be collected and processed in the pellet mill to produce grass pellets (hemp pellets) which are suitable for fuel flexible pellet stoves and boilers. However different biomass materials produce different combustion results, we have seen this through our experiments with our biomass boiler.
While miscanthus and switchgrass both have their merits its hemp which really offers us the best alternative to wood pellets. The problem with other grasses and straws is during combustion they produce a significantly higher ash content than say premium wood pellets. Many pellet stoves and boilers are designed specifically to burn wood pellets with an ash content below 2%, therefore using these grass pellets can create issues. However hemp pellets produce around 2% ash, therefore hemp pellets can be used in a much large range of pellet burners currently on the market today.
Another advantage is that hemp pellets are no more corrosive to burn than wood pellets, while this is not the case with pellets made from straw, miscanthus and switchgrass. The biggest issue with hemp is the current legal restrictions around its growth. Industrial hemp under many laws today is covered under the umbrella of laws restricting the growth of marijuana. While hemp may look very similar to marijuana it is not the same plant, and the THC content of industrial hemp is so small it’s said you would have to smoke a whole field of hemp to feel any effect. Even where hemp is currently legal there are restrictions on its growth. In the UK you can only grow hemp if there is a suitable processor to take your crop.
Hemp pellets are produced from the shiv, which is the woody core of the plant. The fibre is first separated and goes to make clothing and other products. The large shiv particles can then be used in construction in combination with lime. After all this processing has taken place there are small shiv particles remaining and its these particles that can be processed into hemp pellets. While wood is currently where the market is focused, hemp pellets could hold significant market share in the future.