Are renewable energies up to the task?
Based on popularity index and media coverage, renewable energies certainly look like they are high up on the list of things we ought to do. Today, the contribution of non-fossil energies to the global supply is a little short of 20%, but let’s take a more specific look at renewables.
Source: International Energy Agency – Key World Energy Statistics 2008 – Total Primary Energy Supply 2006
Biomass
The first source of renewable energy globally is wood-burning (half of the 20%). It is only renewable though if we burn fewer trees than we plant, which is a big constraint when considering growth potential. If larger portions of land are used to harvest energy, more intensive agricultural practices will be used elsewhere to boost yields and keep the production constant. Such practices are big consumers of fossil fuels and rather harmful to the environment.
It may sometimes make sense locally (for instance, forests in France are gaining in surface) but wood-burning’s contribution to global energy production is unlikely to increase by much.
Hydro
Second on the list is hydroelectricity at 2.2% of global energy supply. There are apparently more than 48,000 large dams worldwide and they prove very useful in Norway (100% of electricity) or Brazil (85%). A significant number of new sites are suitable to produce hydroelectricity (though not in Europe) so there is indeed growth potential: on average, one new dam is built every day.
KWh from waterpower could be increased, with estimates ranging from a factor 2 to 10 but it is not exactly harmless to the environment and trade-offs have to be carefully examined.
Geothermal, solar, wind & biofuels
Geothermal energy comes in third position … way behind. Geothermal, solar, wind, biofuels’ cumulative contribution is a dismal 0.6%.
So what’s the growth potential?
Renewable energies hold a great potential in the long-term. But the imperative to dramatically reduce fossil fuels’ dependence is short-term.
Doubling or tripling the contribution of renewable energies to the global production over the next few decades already sounds ambitious, given the current state. It will be quite a test to see how President Obama’s call to double renewable energy in 3 years plays out.
What should be also be emphasized is that an absolute increase is NOT the end goal: it will only help if this accrued production is a substitute to fossil fuel burning.
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