A biomass boiler is a type of heating system that uses natural or non-fossil fuel resources to create heat for use throughout a home or premises. It works in a similar way to conventional boilers, combusting fuel to produce heat that is then used to heat water. Biomass boilers are normally larger than their fossil fuel-burning counterparts because they burn wood pellets instead of gas, and therefore need to hold a larger volume of fuel. There are four main types of biomass heating systems: fully automated, semi-automated, pellet-fired, and combined heat and power. Pellet-fired systems are the third main type of biomass heating system and are more expensive than other types, but they are more efficient because the pellets are more condensed and uniform. The pellets are stored in a grain-type storage silo, and gravity is used to move them to the boiler. Biomass boilers are designed to work all year round and can be coupled with solar heating or an electric shower to provide hot water during the warmer summer months. Every four weeks or so, the biomass boiler will need to be emptied of the ash, which can be put straight onto a compost heap to help fertilize the soil. Biomass boilers are an environmentally friendly and sustainable alternative to traditional gas or oil boilers used in homes.