Measurements are a delicate issue in complexity. In a previous post, I defined complexity as the existence of non-equivalent representations of the same object of study. The concept of non-equivalence can be explained with reference to metrics: litres are non-equivalent to temperature. There is no conversion that can define an equivalence between the two measurements. Yet, one can measure a swimming pool both in terms of litres of water and in terms of water temperature.
Measurements are used in policy-making to set targets, and to monitor progress towards targets. Think of CO2 emission targets, energy efficiency targets, waste recycling monitoring. When dealing with complex issues, the choice of metrics is not trivial! The issue of non-equivalence reveals that measurements may be precise, but they do not lead to univocal knowledge. As a consequence, policy objects are constituted also through the choice of metrics.
The case of energy
Take the case of primary energy sources: they can be measured in weight, energetic value, or embedded water. The different measures will give very different pictures of how much energy is imported and how much is produced in the EU, and of how much energy comes from fossil fuels and how much from biomass.
Weight – weight is used in material flow analysis (MFA). MFA is used to represent the economy in biophysical terms, that is, by measuring all the material inputs and outputs used by a country. Inputs and outputs are then checked against one another to obtain a mass balance. In the case of energy inputs, MFA would measure the tonnes of fossil fuels and biomass used as inputs to the economic process, and emissions as output. MFA classifies primary energy sources in terms of biomass and fossil energy materials because weight cannot be used to distinguish between wind, solar radiation, and solid or liquid materials. Following this method of accounting, fossil energy materials contribute to about 60% of primary energy sources and biomass to the remaining 40% (Haas et al. 2005)[1]. The EU only imports about 35% of its energy sources by weight.
Energy value – energy value is used in physics to measure the ability to perform work or to heat an object. This concept is used in thermodynamics to study how energy is transformed from one form to another. In relation to the use of energy in the economic process, thermodynamics is used to distinguish between primary energy sources (such as oil, coal, gas, solar radiation, wind, biomass, etc.) and energy carriers (electricity, heat and fuels), thus tracking the transformations that make energy available to different end uses (Giampietro et al. 2012)[2]. According to Eurostat data for 2015, the EU imports about 70% of its primary energy sources and energy carriers. Fossil energy sources account for about 92%, and biomass for 8%, of the primary energy sources used.
Water – water footprint considers the water embedded in products, that is, the water used to produce different goods and services. Water footprint is used to raise awareness about water use, and can be useful if one needs to decide how to produce energy in a water scarce region. In the case of energy, water footprint accounts for (i) the non-consumptive use of water for cooling in thermal power plants, and for hydropower. This water use is considered as non-consumptive because after extraction, water is returned to the ecosystem, although it may be returned with different qualities, for instance, at a higher temperature; (ii) the consumptive use of water used to irrigate biofuel crops. According to the Water Footprint Network, biofuels use more water than gasoline[3], so that this eco-friendly solution is not water-friendly; (iii) the consumptive use of water in mining, the extraction of fossil primary energy sources. According to water footprint, biomass has the highest water footprint, followed by hydropower. This method of accounting favours the use of wind and solar energy. In the EU, biomass accounts for about 75% of the water footprint for electricity and heat (Mekonnen et al. 2015)[4]. As opposed to the previous methods, water footprint focuses on energy carriers, and thus its accounting is not equivalent to MFA. This means, the 75% figure does not consider biofuels. In terms of openness, the EU imports about 14% of its biofuels according to Eurostat.
Why do metrics matter?
The ratio of fossil to alternative energy sources is at the basis for target setting and monitoring of the Renewable Energy Directive. In terms of energy security, it is important to know how much the EU depends on imports. In both cases, there is not one answer. Complexity is not a problem of right or wrong evidence. In this context, numbers are representations, not observer-independent facts. The trivial point is that different methods serve different purposes. The far from trivial point is that the choice of metrics is not a technical decision, as it impacts the way the problem is framed. The existence of multiple non-equivalent metrics makes the choice of measurement a normative choice, a political choice, a necessary choice that cannot be solved by science alone.
References:
[1] Haas, W., Krausmann, F., Wiedenhofer, D. and Heinz, M. (2015), How Circular is the Global Economy?: An Assessment of Material Flows, Waste Production, and Recycling in the European Union and the World in 2005. Journal of Industrial Ecology, 19: 765–777
[2] Giampietro, M., Mayumi, K. and Sorman, A. (2012), The Metabolic Pattern of Societies: Where Economists Fall Short. Routledge, 408 pp.
[3] https://www.watercalculator.org/water-use/the-water-footprint-of-energy/
[4] Mekonnen, M., Gerbens-Leenes, P. and Hoekstra, A. (2015), The consumptive water footprint of electricity and heat: A global assessment. Environmental Science: Water Research & Technology, 1-15.
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