Fuels are chemicals or mixtures of chemicals that burn relatively easily with air. The products of fuel combustion are mainly gases, discharged into the atmosphere (exhaust).

Choosing the right fuel for heating is critical to the running costs of a building. The fuel you choose will determine your heating costs, both in the near and the immediate future, and whether or not you have to go to the trouble of heating.

Choosing the right type of fuel will always require some compromise. Solid fuels provide the lowest heating costs. But, it is necessary to have sufficient space in the building for fuel storage and to purchase the fuel in advance. In some cases, the user of a solid fuel boiler will have to spend some time finding the right quality of fuel – here again, everyone has to choose whether to buy cheaper, low-quality fuel or to invest in high-quality fuel.

Solid fuel boilers, to a greater or lesser extent, require maintenance related to adding fuel, removing ash, regular cleaning of the boiler and appropriate setting of the automatic control system and adjustment of the device’s operation to the changing heat demand of the building.

Maintenance-free heating is provided by gas, fuel oil or electricity boilers. However, comfortable heating can cost a lot and it is worth bearing this in mind when choosing the right fuel.

Figure 1: Estimated cost of generating 1 kWh of thermal energy with different fuel types.

The estimated costs of heating a 140 m2 building with different fuels can be seen in the graph below.

Types of fuel

For heating of single family houses as well as large buildings we can choose almost any type of fuel. They differ in the way they are produced, their properties and have corresponding requirements.

We can divide fuels into solid, liquid and gas, natural and artificial, low and high calorie.

Biomass. These are solid or liquid substances that are biodegradable. They come from agricultural production, forestry and industries processing these products.
For heating purposes biomass is most often used in the form of wood and its waste: wood in pieces, chips, woodchips, sawdust, pellets. Also obtained from energy crops, such as energy willow.
For heating the building can also be used biomass derived from agricultural production, such as straw, cereal grains, corn.

Coal. Hard coal or lignite is sold in different forms, with different granulation (grain size) and class. And the grade of coal depends on its calorific value and ash content.

Natural Gas. It comes from natural deposits and its main ingredient is methane. It is odourless and non-poisonous – therefore, it is odourised to give it a specific smell detectable in case of a leak in the gas installation and, consequently, it increases the safety of its use.

Liquefied Petroleum Gas. It is a mixture of hydrocarbons consisting mainly of propane and butane. It is obtained from wet natural gas and refinery gases. These mixtures become liquids under vapor pressure.

Heating oil. So-called light fuel oil is used for heating homes. To distinguish heating oil from diesel fuel, it is colored red.

Bio-oil. Obtained mainly from rapeseed. After chemical processing its properties are similar to
properties are similar to those of fuel oil. Modern oil-fired boilers can be operated with
Modern oil-fired boilers can be fuelled with a mixture of standard fuel oil and bio-oil with a proportion of approx. 10%. However, burners designed to burn bio-oil alone can also be found.

Biogas. It is formed during the decomposition of organic substances under anaerobic conditions. For the production of
Biogas can be produced from e.g. green manure, plant silage and liquid manure.

At present, biogas is mostly used locally for cogeneration of electricity and heat.
electricity and heat. It supplies so-called cogeneration units that provide heat and electricity to e.g. housing estates, industrial plants
e.g. for housing estates, industrial plants. Biogas powers the combustion engine of the unit, which drives the generator.
The electricity produced is used for own purposes or is fed into the power grid.
The waste heat from cooling the chiller is used to heat buildings.

Biogas can also be added to natural gas and transported over long distances using
using existing infrastructure. Thus, it can be burned in domestic boilers in
near or far.

Fuel Calorific Value.

The basic parameter of each fuel is its calorific value. It corresponds to the amount of heat obtained from burning a unit of fuel (e.g. 1 m3 of gas), when the water contained in the flue gas is in the form of steam.

The heat of combustion determines the amount of heat obtained from the complete combustion of a unit of fuel, with the water vapor formed during combustion condensing and giving up its heat of vaporization.

Calorific values of selected fuels:

FuelMinimum calorific values MJ/kg or MJ/m3
Wood granules17,5
Lignite briquettes19,25
Hard coal30,1
High-methane natural gas type E (GZ-50)31,0
Light fuel oil42,8