Residual value method

This article deals with the residual value method in joint production. For further meanings, see the residual value method of imputed interest .

The residual method is a method from the cost accounting , which in joint production each product cost assigns. The cost of the input is allocated to the main product. The value of the by-products is deducted from this. The remainder is the value of the main product.

The residual value method results from the allocation of all costs incurred in cost center accounting.

Derivation

Derivation using the example of a two-dimensional joint production with input and the primary product and the secondary product . be the respective variable costs. ${\displaystyle I}$ ${\displaystyle O_{1}}$ ${\displaystyle O_{2}}$ ${\displaystyle k}$

${\displaystyle {\text{Wert des Inputs}}={\text{Wert des Outputs}}}$

${\displaystyle k_{i}\cdot I=k_{1}\cdot O_{1}+k_{2}\cdot O_{2}}$

${\displaystyle k_{1}={\frac {(k_{i}\cdot I-k_{2}\cdot O_{2})}{O_{1}}}}$

criticism

The criticism of the residual value method is that the costs of the by-product are specified externally and do not result from the properties of the coupling process. The price of the by-product influences the costs of the main product without changing the price of the input material or the process properties. ${\displaystyle O_{2}}$ ${\displaystyle I}$

Example: differential efficiency

In CHP systems , the residual value method can be used to calculate the differential efficiency, i.e. the output of electrical energy divided by the additional fuel requirement compared to the reference boiler, i.e. H. The CHP process receives a fuel credit for the supply of heat in the amount of the fuel required by the reference boiler.

${\displaystyle {\text{differentieller Wirkungsgrad}}={\frac {\text{Mehrertrag an elektrischer Energie}}{\text{Mehrbedarf an Brennstoff}}};\quad \eta _{el,diff}={\frac {\eta _{el,KWK}}{1-{\frac {\eta _{th,KWK}}{\eta _{th,ref}}}}}}$

with
η _{el, KWK} : electrical efficiency of the CHP system
η _{th, KWK} : thermal efficiency of the CHP system
η _{th, ref} : thermal efficiency of the reference boiler

If the overall efficiency of the CHP system is the same as the thermal efficiency of the boiler, i.e. H. η _{el, KWK} + η _{th, KWK} = η _{th, ref} , the differential efficiency of electricity generation is equal to the efficiency of the boiler.

${\displaystyle \eta _{el,diff}={\frac {\eta _{el,KWK}}{1-{\frac {\eta _{th,KWK}}{\eta _{th,ref}}}}}={\frac {\eta _{el,KWK}}{1-{\frac {\eta _{th,KWK}}{\eta _{el,KWK}+\eta _{th,KWK}}}}}={\frac {\eta _{el,KWK}}{\frac {\eta _{el,KWK}}{\eta _{el,KWK}+\eta _{th,KWK}}}}=\eta _{el,KWK}+\eta _{th,KWK}=\eta _{th,ref}}$

In the same way, the differential efficiency of the heat generation can be calculated, i.e. the heat generation divided by the additional fuel requirement compared to the reference power plant.

${\displaystyle {\text{differentieller Wirkungsgrad}}={\frac {\text{Mehrertrag an thermischer Energie}}{\text{Mehrbedarf an Brennstoff}}};\quad \eta _{th,diff}={\frac {\eta _{th,KWK}}{1-{\frac {\eta _{el,KWK}}{\eta _{el,ref}}}}}}$

See also

• Cost unit accounting
• Equivalence digit method
• Finnish method
• Carnot method