TAPPING UNUSUAL QUARTERS

How to fit four elephants into a small car

There is an old joke that goes “How do you get four elephants in a small car?”. In case you haven’t heard this one before, the answer is: “Very simple, two in the front and two in the back”. I am reminded of this joke each time I stumble across a proposal for future energy policies coming from anti-nuclear quarters. I have in front of me an example of such a prospective study commissioned by a well-known anti-nuclear NGO. This one is dated September 2005, but it does not differ from many other similar, older analyses. It provides figures according to which, between 2010 and 2050, a moderately decreasing EU population would be consuming 31% less energy but generating 66% less carbon dioxide. In addition, during this period of time, the EU Gross Domestic Product (GDP) per capita would nevertheless increase by 148%.

It is all well and good to announce such favourable developments. But how likely are they to happen? To analyse the prognosis, it is useful to recall Kaya’s identity. This too-little-known formula¹ links the level of CO₂ emissions (C) to the main parameters that impact upon it. It goes as follows:

E, G and P stand for energy consumption, GDP and population respectively. Since this equation reduces to C = C after all simplifications have been performed, nobody can question its validity. Relation (1) fulfils two useful tasks. First, it introduces the parameters – in addition to population – that are actually relevant here: the carbon content of energy (C/E), the energy content of GDP (E/G) and the GDP per capita (G/P). Please note that the relation is applicable globally either to the whole world, to a town, a country or a group of countries. Second, it helps highlight the fact that the meaningful parameters cannot be acted upon independently. To see how this is true, the identity must be adapted to account for small variations in the above factors. With the help of a little maths one can transform it into the following relation:

In plain English, the relative (%) changes in CO₂ emissions are constrained by the relative changes in carbon content of energy, energy content of GDP, GDP per capita and population. It is worthwhile observing that the rate of population change is imposed but not known accurately when applied to periods of time exceeding one generation (25 years). GDP growth is, similarly, not well under control, but it is clearly desirable to maintain it at a healthy level (say, not below 2%). At the end of the day, the only parameters which we can hope to influence are carbon intensity (C/E) and energy intensity (E/G).

Let us now apply relation (2) to the EU figures. The target of reducing CO₂ emissions by 70% by 2050 translates into a yearly reduction of 2.64%. Hence:

The EU population in the above-mentioned study is assumed to peak at around 2010 and then decrease slightly over the next forty years. Over the latter period, this corresponds to a yearly decrease of 0.2%.

Finally, a 2.3 % yearly growth rate of GDP per capita is assumed. Applying these figures to relation (2) yields the following:

In other words, reducing CO₂ emissions by 70% while allowing the EU population to enjoy a 2.3% yearly increase in GDP, implies that the combined decrease of carbon content of energy and the energy content of GDP is maintained close to 5% per year. There is no escape clause: if the latter conditions are not fulfilled, the former objectives cannot be met².

The above relation and the ensuing considerations shed useful light on the CO₂ reduction debate. I shall restrict myself to the following observations:

• Starting with sets of figures describing the evolution of C, E, G and P over time will automatically satisfy relation (2) since it is an identity, but this won’t help. To serve any purpose, Kaya’s identity must be used in conjunction with independent estimates of what would be achievable in terms of decrease in energy content of GDP and carbon content of energy. Once these estimates have been obtained, they should be used as input to relation (2) to see if they balance out and used to fine-tune the target rates if they don’t.

• Technical and financial constraints are factors to be taken into account when performing the independent assessments mentioned above: availability of (renewable) resources, technical integration of those resources in an overall energy generation system and cost of implementation. One would be hard-pressed to find any analysis of these factors in any anti-nuclear report.

• Based on recent trends, the European Commission expects a 1.6% yearly decrease in energy intensity over the next thirty years. The figures found in the above-mentioned anti-nuclear study lead to 3.16% per year, almost double the EC value. It remains to be explained, therefore, precisely what would permit such a quantum leap in energy efficiency to occur. Should the EC be proven right, and assuming that the rate of decrease of carbon content and the same population change are applicable, Kaya’s identity tells us that GDP growth in the EU would have to be limited to 0.74% (2.3% – 3.16% + 1.6%) in order to stick to the initial CO₂ reduction objective. Few would consider this a rosy prospect.

To produce papers stating that we can achieve yearly decreases in carbon content and energy content close to 5% is one thing. The devil being in the detail, it is also necessary to be extremely concrete about how this is going to happen and why it will happen in the future - all the more so when the evidence available does not support the objective submitted. Failing that, any report that draws a roadmap to a carbon-poor future will be about as useful as advice about how to fit four elephants in a small car.

¹ First published in 1989, Kaya’s identity is recalled only in pro-nuclear or neutral literature. It is as though its inescapable logic was seen by the anti-nuclear camp more as a hindrance than as a tool for analysis, which it is in fact.
² If the whole world had been considered, the conditions would have been even more stringent: the population rate of change would have jumped from -0.1% to +0.85% (almost a 1% increase) and some emerging countries seem all set to exceed the 2.3% yearly increase in GDP.
³ This is already fairly optimistic since the past 30 years to 2000 indicate a rate of roughly 1.3%. See Annex 3 of the EC’s Green Paper on Energy Efficiency ‘How to do more with less’ document COM(2005) 265 final of 22 June 2005.