Some of the most popular renewable energy sources are based on technology that requires scarce resources, which makes their widespread use problematic. New technologies are on the horizon, but the feasibility of fuel cells and solar panels remains very much up in the air at this point.

Today's photovoltaics are made primarily from silicon, which in the 1990's was derived only from the silicon waste that came from the silicon chip industry. In April, media reports surfaced from the biggest PV companies that solar-grade silicon leapt from $9 per kilo in 2000 to $25 last year, and $60 in 2005. These higher prices are a result of the fast growth rate of the global photovoltaics industry, which produced more than 1.2 Gigawatts in 2004, and the efficiencies in the traditional silicon chip industry, which leave less wastes from their process for solar-grade silicon.

Recent advances in nanotechnology may overcome this bottleneck, but that will take time to development and peak oil is looming ever closer.

Most modern fuel cells require expensive metals, such as platinum, in order to create electricity. Back of the envelope math demonstrates that if all cars on the road today were fitted with fuel cells (forget the other technological difficulties), it would require the entire known reserves of platinum in the world.

Recently, researchers are reporting that iron-sulphur compounds can be effective. This can significantly reduce the cost of the materials necessary for the construction of fuel cells and, through that, reduce the cost of the fuel cells themselves. But again, time is short and we are only now exploring more feasible alternatives,

We are in a race against time, a race in which we allowed thrity years to pass before we decided to start running.