Biomass heating

What is Biomass heating?

In energy terms, biomass heating refers to the use of a wide variety of organic material for the generation of heat.

Biomass is any form of biologically produced matter, which can be burnt as a fuel. Common sources of biomass fuel include forestry waste, sawmill residues, and dedicated energy crops, such a miscanthus grass and willow coppice.

Biomass is an environmentally friendly renewable source of energy. The use of biomass to meet energy needs is a 'carbon-neutral' process because the carbon dioxide released during combustion is balanced by that absorbed by the plants during their growth.

Biomass can be used to provide energy for many applications, from domestic and commercial space heating up to industrial-scale combined heat and power (CHP). Modern biomass boilers are easy to operate and in many cases the cost of heat from biomass is lower than the fossil fuel equivalent.

There are four types of biomass generall in use today: 1) wood and agricultural products; 2) solid waste; 3) landfill gas; and 4) alcohol fuels.

Wood chips constitute one of the most economical forms of biomass fuel, as they can be burned with little or no preprocessing.

The use of biomass energy has the potential to significantly reduce carbon dioxide emissions. Burning biomass releases carbon dioxide. However, when fossil fuels are burned they release carbon dioxide that was captured by photosynthesis millions of years ago— thus an essentially "new" greenhouse gas is being released into the atmosphere. Biomass, on the other hand, releases carbon dioxide that is largely balanced by the carbon dioxide that has been captured in its own growth, over a much shorter time period. Consequently, displacing fossil fuels with biomass should result in significantly lower net carbon emissions to the atmosphere.

Seventy-nine percent of the biomass we use today comes from burning wood and wood scraps - The rest of the biomass comes from crops, garbage, landfill gas, and. alcohol fuels.

Who uses biomass energy? Industry is the biggest user of biomass. Seventy-seven percent of biomass is used by industry.

Homes are the next biggest users of biomass energy. About one-fifth of American homes burn wood for heating. Three percent of homes use wood as their main heating fuel. For small-scale domestic applications of biomass the fuel usually takes the form of wood pellets, wood chips or wood logs

Electric utilities also use biomass energy to produce electricity. One percent of biomass is used to make electricity. Still, biomass produces only a tiny amount of the electricity we use in this country.

Environmentally, biomass has some advantages over fossil fuels such as coal and petroleum. Biomass contains little sulfur and nitrogen, so it does not produce the pollutants that cause acid rain. Growing plants for use as biomass fuels may also help keep global warming in check. That's because plants remove carbon dioxide--one of the greenhouse gases-from the atmosphere when they grow.

You should consider the following issues if you're thinking about a biomass boiler or stove. An accredited installer will be able to provide more detailed advice.

The cost for boilers varies depending on the system choice; a typical 15kW (average size required for a three-bedroom semi detached house) pellet boiler would cost around £5,500 - £12,000 installed, including the cost of the flue and commissioning. A manual log feed system of the same size would be slightly cheaper. A biomass powered boiler could save you around £200 a year in energy bills and around 8 tonnes of C02 per year. Your biomass boiler may be fitted in the same position as your current boiler, depending on space. A biomass boiler that would heat a 2 to 3 bedroom house or a commercial unit up to 3000sq ft would fit in a 2M cube space. The hopper could be next to it or remotely placed; depending on model.

Unlike other forms of renewable energy, biomass systems require you to pay for the fuel. Fuel costs generally depend on the distance from your supplier and whether you can buy in large quantities.

The DTI funded low carbon buildings programme provides grants to help with the costs of installing biomass technologies.

[www.energysavingtrust.org.uk/generate_your_own_energy/types_of_renewables/biomass/]

Ask the right questions when sourcing a biomass heating system

The most important things to consider when searching for a biomass heating system are to know your needs and ask the right questions of a potential biomass heating system manufacturer.

In a survey of nearly 100 manufacturers of biomass heating systems in the United States and Canada with the capability of serving light industrial / commercial purposes and agricultural needs, AURI identified the most important questions to ask:

  • 1. Does the rated heating capacity in BTU per hour refer to BTU input or BTU output?
  • 2. Does the biomass-burning unit have Underwriters Laboratories (UL) or Canadian Standards Association (CSA) certification on the testing label?
  • 3. Does the operator's manual for the unit state what biomass material (or combination of materials) can be burned for good performance?
  • 4. If the biomass burner can effectively burn various biomass materials, what adjustments or modifications are required to burn the different biomass fuels?
  • 5. How often will the supply hopper need to be filled with biomass when the unit is burning at full capacity?
  • 7. What are the maintenance requirements of the biomass burner compared to other heating units? How often do clinkers need to be knocked loose and removed? Must an additive (such as oyster shells) be burned along with the biomass to ease the cleaning requirements?
  • 8. Are sugars from burning the biomass likely to accumulate in the combustion chamber? If so, what is the recommended way to remove the sugars?
  • 9. What is the availability of biomass products in your area? What are the storage requirements for the biomass you purchase for the heating season and perhaps beyond?
  • 10. What is the recommended moisture content for the biomass to get most efficient performance of the biomass burner?
  • 11. What type of exhaust ventilation system must be provided for the biomass burner? What are the local code requirements and insurance requirements for handling the combustion exhaust?
  • 12. What capacity biomass burner is needed for the intended application? Is the building layout appropriate for the convective movement of the heated air throughout the whole building? Will the biomass burner be used to serve as the primary heat source for the building or if it is intended to serve as a supplementary or back-up source?
  • 13. Can the biomass burner be connected with an existing hot water or hot air distribution system?
  • 14. How much experience does the dealer have with installing and servicing biomass-burning stoves and boilers?
  • 16. What warranty comes with the biomass burner? Under what conditions will the warranty be voided?

[www.auri.org/Biomass/finding_a_manufacturer2.htm]

Webpage by Seamus Waldron