In this model, a contractor or broker (or other 3rd party) purchases the biomass and undertakes the necessary activity in feeding it into the downstream supply chain. Volumes/energy content must be determined on site at, or after, harvesting. Once again, established BEF can be utilised or the volumes can be estimated from pile dimensions and local guidelines. The advantage for the forest owner is one of a small (but somewhat uncertain) income on site and no responsibility for costs to contractors and uncertainties of supply. The benefit to the energy conversion plant is a longer term relationship with a single supplier representing many forest owners.

Standard models for determining energy content in the supply chain are given below:

6.8.3.1 At the plant

Ultimately the bioenergy plant determines and pays for the energy content of

biomass being delivered though its gates. This is done for chips as follows:

1. The (registered) truck driver notes the origin of the biomass on the incoming weighbridge bill, which includes a timestamp. The registration of trucks includes the details of the supplier for whom they are transporting.

2. The driver (or staff member) takes a bucket sample of the chips while they are being poured into the chip bunker — ensuring it is as representative as possible. Some plants are equipped with fully automated sampling devices that bore into the load while still on the truck.

3. The sample is placed in a drying oven together with the weighbridge bill

4. After 24 h at 105° C, the dry matter content of the load is calculated and remuneration to the supplier is affected.

When it comes to other forms of biomass (FT or residues), it is not possible to make accurate estimates of energy content before the material is chipped and dried. With well-developed delivery systems, e. g., from uniform plantation forestry, conversion figures including norms and standard deviations can be developed rapidly and improved on with time. Here, the supplier is paid a value derived from e. g., mean moisture content per specie and season.