Exergy, Power, Work

How can we estimate natural resource useful work flows?

Exergy services are an essential factor of production derived from natural resource capital. They represent an extension of the 'standard' OECD factor accounting methods to natural resources, by stratifying the goods and services from natural resources according to the 'useful work' delivered to the economy.

The amount of useful work delivered per unit of primary resource exergy (both expressed in standard energy units) is determined by the technical efficiency of primary exergy conversion.

To calculate efficiencies we can disaggregate by the type of exergy service (work) delivered to the economy.

We have identified 6 main types of fuel and non-fuel 'exergy service'. The groupings do not correspond to standard sectoral definitions.

Prime movers
Other prime movers
Space heat
Process heat

The efficiency of each exergy service grouping is determined largely by three factors:

1. the intrinsic 'quality' of the energy carrier (coal, oil, gas, renewable)

2. the available technology

3. and economies of scale

Experience delivering exergy services and R&D have improved the individual technical efficiency of exergy conversion for each energy carrier and exergy service. Figure 1 shows the technical efficiency learning curves for the three major energy carriers of the 20th century calculated using data from the US over the period 1900-2000.They were provided by disaggegating fuel use according to the work each supplied, according to these schematics. Figure 1 shows how the dirtiest and most polluting fossil fuel, coal, is used most efficiently. Nevertheless, at only approximately 30% thermal efficiency, there is still room for improvement.The improvements in technical efficiency can be modeled as learning processes.


This site was created by Dr.Benjamin Warr

email to: Benjamin.Warr@free.fr