Not all renewable power systems are sustainable

Some renewable energy systems rely on scarce resources

In the quest for alternatives to fossil fuels, renewable energy systems are being rapidly developed across a wide spectrum. However, the fact that these new systems replace depletable fossil fuels with renewable sources is in itself not a guarantee of high sustainability. The article 'Why sustainable power is unsustainable' in New Scientist draws attention to this often under-appreciated fact. In our growing focus on energy and climate change, we have a tendency to applaud every renewable energy technology that is being developed and without considering its other sustainability aspects.

The New Scientist cites three examples of "unsustainable sustainable power systems":

1. Multiple-junction PV cells, which have promising performance in so far as efficiency goes, but use the relatively rare metal Indium
2. Hydrogen fuel cells, which use the very scarce metal Platinum as a catalyst (but then again: is hydrogen really a source of renewable energy, or only an alternative energy carrier?)
3. Bio-fuels, which make use of large areas of scarce arable land

Renewable energy systems that rely on rare metals such as indium or platinum do not have the potential to take us towards a global zero carbon emission economy. That said, all renewable energy systems make use of materials which are available in a more or less limited supply. This does still not mean that their negative impact is as great as that of fossil fuels. Life Cycle Analyses clearly show that energy use has in general a far greater environmental impact than material use.

And even the development of those renewable energy systems which make use of very scarce materials is not necessarily a wasted effort. Such systems can be quite useful during a transition period and the technical developments that were realized designing them can be the starting point for further development towards more sustainable alternatives.