### Minimal impact on climate change

The first point to be made is that the chances of renewable energy being deployed at a rate sufficiently high to have a meaningful impact on climate change are slim to none. Leading energy authorities such as the IEABP, the EIA and Exxon all agree that renewable energy other than hydro will probably contribute about 5% of the global energy mix by 2035. By that time, atmospheric CO2 concentrations will already be well past 450 ppm.

Even if all of these energy experts are off by 100% and renewable energy sources like solar, wind and biofuels contribute 10% of global energy by 2035, global CO2 emissions will still be increasing, rapidly driving atmospheric concentrations towards 550 ppm and beyond. Decarbonizing the energy sector by other means (e.g. CCS and nuclear) will be much more effective.
The logical purpose of renewable energy is long-term energy security through serious market-driven deployment probably starting somewhere in the second half of this century. Continuing current attempts to combat climate change in the slowest, least practical and most expensive way possible (the heavily subsidized deployment of currently available renewable energy technology) is sure to do much more harm than good in the long run.

### The price of intermittency

It is very convenient for renewable energy advocates to simply neglect the potentially very large costs associated with the intermittency of renewable energy. As a result of climate variability, the output from technologies like wind and solar varies substantially over a wide range of timescales – minutes, hours, days, weeks, months, years and even decades. Accommodating this wide range of variations will require a wide range of additional infrastructure from the following categories:
• Fossil fuel power stations operating at low efficiency and low capacity factors.
• A large renewable energy overcapacity with unwanted energy spikes being grounded.
• A wide range of material and energy intensive storage mechanisms which also involve substantial energy losses in the conversion process.
• Technically, economically and politically complex international HVDC supergrids capable of distributing energy from wherever the sun is shining and the wind is blowing.
Currently, there is insufficient information available to accurately estimate the costs associated with the intermittency of renewable energy, but current storage technology can give some rough indication. Adding battery packs capable of smoothing daily variations will roughly double the price of domestic solar PV, while chemical storage options capable of smoothing out longer-term variations lose about half of the original energy in the conversion process. It is possible that battery prices fall over coming decades (although they may also rise due to material shortages and waste processing regulations), but the efficiencies of chemical storage cannot be improved much further. Thus, it can be estimated that a storage dominated solution will cost at least as much per Watt installed as current solar PV and most probably more.

### Insufficient energy return

The third point is related to Energy Return on Investment (EROI). A highly complex society (such as the developed world) where the vast majority of energy is used for a myriad of purposes other than energy harvesting places very high demands on the quality of energy resources. EROI expert, Charles Hall, estimates that we need an EROI of about 10:1 to maintain current societal complexity (click image for source).

Solar and wind have an EROI of about 7:1 and 18:1 respectively, but this is before the effect of intermittency is accounted for. When 4 hours of battery storage is added to solar PV, the EROI drops to just over 2:1 (additional energy costs of panel installation and extra distribution losses are also included). This kind of EROI cannot even sustain the most basic of civilizations, which is a problem because we will need a very advanced civilization to make high-tech renewable energy work. This simply implies that we still require decades of basic RD&D before renewable energy hopefully reaches the point where it can realistically support our civilization.

### The externality misconception

Finally, we have to look at externalities – one of the favourite words of renewable energy advocates. Yes, it is true that, at current penetration rates (87% fossil fuels and 1.5% renewables other than hydro), the negative externalities of fossil fuels are larger than those of renewables. A comprehensive EU review study produced the following median estimates in 2006 Euro cents per kWh:
 Coal Peat Oil Gas Nuclear Biomass Hydro PV Wind 4 2.5 3 1 0.3 1 0.2 0.6 0.125

If, however. through some magical worldwide renewable energy mobilization, the number of solar panels and wind turbines was rapidly increased by a factor of 100, energy storage superstructures sprouted up everywhere and thousands of HVDC cables criss-crossed the countryside in 70 m wide cleared channels, renewable energy would suddenly appear much less green. Vast chunks of nature would be impacted by renewable energy infrastructure, the hazards of rare earth mining would rival those of coal today and e-wastes from decommissioned panels, batteries and turbines would be a major concern.
In parallel, the externalities of fossil fuels would shrink substantially. Air pollution would fall below danger levels, fossil fuel extraction would become safer and less environmentally destructive as lower quality resources are abandoned, and CO2 emissions would fall below the rate at which they are absorbed by the Earth. In fact, it is highly likely that, by the time renewables finally supply the majority of our energy, we will realize that the negative externalities of renewables are now greater than those of fossil fuels.
But the most important negative impact of such an explosive renewable energy expansion would be a rapid rise in energy prices and, with it, a rapid rise in the price of virtually everything else. The primary positive externality of fossil fuels (which is almost never acknowledged) is that cheap and abundant fossil energy with its highly convenient built-in concentrated energy storage neatly packaged in solid, liquid and gaseous forms facilitated virtually every innovation that has brought the great increases in standard of living and life expectancy enjoyed by everyone reading this text. Removing fossil fuels before we have viable alternatives will reverse this externality to the great detriment of society.

### The sustained exponential growth fantasy

Despite these arguments, however, renewable energy advocates will probably still believe that renewable energy deployment can somehow continue growing at 20% p.a. for the next four decades, ultimately granting us a paradise of clean and "free" energy where the friendly robots of the year 2050 install solar panels at a rate 1000 times that we manage today. The next post will specifically target this misconception with a detailed look at the law of receding horizons: the tendency of renewable energy deployment to become progressively more difficult as the total installed capacity increases.