Solid bio fuels: guaranteeing the energy we produce

In terms of the environmental challenges facing us, solid bio fuels have a lot to offer. Indeed, this source of energy has been enjoying renewed interest since the rise to popularity of so-called sustainable heating. But how can we guarantee the quality of these “new” sources of energy? One key fact: moisture content.

CEN standards: certification of MWh supplied

Set out by the European Committee for Standardisation (CEN) in December 2005, Technical Specification 14961:2005 (NF XP CEN/ TS 14961) proposes a classification and characterisation of solid bio fuels according to:

• Source
  • Agricultural and sylviculture products,
  • Vegetable waste from agricultural and forestry vegetable waste,
  • Wood waste...
• Moisture content (% of mass on reception)
• Lower Heating Value (MJ/kg on reception) or energy density (apparent KWh/m3).

Bio fuel supply contracts rely on these criteria to determine the reliability of the energy supplied to their boiler rooms and to guarantee the megawatt hour (MWh) supplied.

Moisture: one key factor for calculating MWh

The amount of MWh depends both on the weight and moisture content of the bio fuel:

Bio fuel weight or volume + moisture content = MWh

Crucially, the moisture content also helps:

• Limit the risk of boiler breakdowns,
• optimise the thermal efficiency of the combustion plants,
• Control emissions and prevents deterioration in the air quality,
• Stabilise energy costs without having to pay a water premium,
• Reduce storage and drying costs.

Save time and money by measuring moisture content on site

To be able to measure moisture content precisely, you need to know two important factors:

• How representative the sample is,
• The reliability of the instrument used for measuring.

Oven drying is the recommended method for determining water content precisely. However, apart from its cost (as an example, between 30 and 70€ per measurement *), it takes time:

• 20 to 40 min to measure each sample
• 24 hrs to get the results

Portable moisture meters are an alternative to oven drying.

Calibrated according to the CEN/TS14961:2005 standard, Humitest for granules and Humitest for bio mass all have an advantage: they can be used for instant, reliable measurements on site, thus limiting handling costs relating to non-conformity of the fuel and optimising operation of the fuel plants.

* Source Ademe.