Gail Tverberg writes at The Energy Collective:
Myth 8. Renewable energy is available in essentially unlimited supply.
The issue with all types of energy supply, from fossil fuels, to nuclear (based on uranium), to geothermal, to hydroelectric, to wind and solar, is diminishing returns. At some point, the cost of producing energy becomes less efficient, and because of this, the cost of production begins to rise. It is the fact wages do not rise to compensate for these higher costs and that cheaper substitutes do not become available that causes financial problems for the economic system.
In the case of oil, rising cost of extraction comes because the cheap-to-extract oil is extracted first, leaving only the expensive-to-extract oil. This is the problem we recently have been experiencing. Similar problems arise with natural gas and coal, but the sharp upturn in costs may come later because they are available in somewhat greater supply relative to demand.
Uranium and other metals experience the same problem with diminishing returns, as the cheapest to extract portions of these minerals is extracted first, and we must eventually move on to lower-grade ores.
Part of the problem with so-called renewables is that they are made of minerals, and these minerals are subject to the same depletion issues as other minerals. This may not be a problem if the minerals are very abundant, such as iron or aluminum. But if minerals are lesser supply, such as rare earth minerals and lithium, depletion may lead to rising costs of extraction, and ultimately higher costs of devices using the minerals.
Another issue is choice of sites. When hydroelectric plants are installed, the best locations tend to be chosen first. Gradually, less desirable locations are added. The same holds for wind turbines. Offshore wind turbines tend to be more expensive than onshore turbines. If abundant onshore locations, close to population centers, had been available for recent European construction, it seems likely that these would have been used instead of offshore turbines.
When it comes to wood, overuse and deforestation has been a constant problem throughout the ages. As population rises, and other energy resources become less available, the situation is likely to become even worse.
Finally, renewables, even if they use less oil, still tend to be dependent on oil. Oil is important for operating mining equipment and for transporting devices from the location where they are made to the location where they are to be put in service. Helicopters (requiring oil) are used in maintenance of wind turbines, especially off shore, and in maintenance of electric transmission lines. Even if repairs can be made with trucks, operation of these trucks still generally requires oil. Maintenance of roads also requires oil. Even transporting wood to market requires oil.
If there is a true shortage of oil, there will be a huge drop-off in the production of renewables, and maintenance of existing renewables will become more difficult. Solar panels that are used apart from the electric grid may be long-lasting, but batteries, inverters, long distance electric transmission lines, and many other things we now take for granted are likely to disappear.
Thus, renewables are not available in unlimited supply. If oil supply is severely constrained, we may even discover that many existing renewables are not even very long lasting.
wind power, wind energy, environment, environmentalism