The continued existence and expansion of human civilization is wholly dependent on affordable sources of energy. The latest study just released by the National Renewable Energy Laboratory (an organization that exists to study and promote the viability of renewable energy) suggests that it may be possible to get 80% or so of our electric power from renewable sources by 2050. The study also (inadvertently) provides evidence that renewable energy will be a minority player in humanity’s energy portfolio.

The results may disappoint my fellow solar enthusiasts because it suggests that only 13% of our electric energy will come from solar. Distributed solar enthusiasts (who favor photovoltaic solar panels on rooftops) will be further disappointed because half of that 13% will come from water-sucking centralized concentrated solar thermal power plants, many located in desert ecosystems, leaving only about 6% for solar panels on rooftops, of which many will probably not be on rooftops but in centralized power plants, probably displacing ecosystems or crops.

But electricity represents only 40% of our energy needs. If we hog up all renewable energy sources for electricity, there won’t be any left for the other 60% of our energy needs. In other words, the study tells us that only 32% of our total energy needs can be “potentially” renewable. I.e., it is going to need a lot of help from other energy sources–fossil fuels or nuclear. Liquid biofuels were not part of this study even though they can be used to make electricity and heat homes in place of electricity:

Grist thanks its sponsors. Become one.

However, the modeled scenarios also did not explicitly assume any competition for biomass resources, including from transportation demand for biofuels

The definition of renewable isn’t as clear cut as you might think because it involves the fourth dimension–time. Wind and solar fit the definition of renewable because their power source (the sun) is very long-lived. As long as humanity can keep the panels, turbines, and grid maintained, they will convert solar radiation from a giant nuclear reactor in the sky into electricity in perpetuity.

Grist thanks its sponsors. Become one.

Corn ethanol is considered a renewable energy source (by its proponents) even though roughly 75% of its energy content is derived from fossil fuels. It is in reality, no more renewable than fossil fuels.

Hydro power, like wind, is also ultimately powered by the sun’s energy, making electricity from the potential energy of stored precipitation. But now the definition of renewable runs into trouble because the machines that extract that potential energy (dams) have limited practical life spans:

You can do just about anything in this world (or other worlds– mining the moon) if you have enough money. However, removing the silt from behind most dams is not considered to be an economically viable option. The cost of decommissioning all of these dams is something humanity will eventually have to deal with. In short, one can easily argue that hydro does not fit the definition of renewable (especially by the year 2050–the time frame for this study). Removing it from the NREL study, we find that only 68% of our electricity can come from renewable sources (27% of our total energy).

Inversely, one can argue that because conventional nuclear energy can produce just as much energy for just as long as hydro, it fits the definition of renewable as well as hydro does, and to make matters worse, so do fossil fuels (as is argued by Matt Ridley in his latest book).

It gets worse. The study also assumed that a lot of biomass (15% of the energy mix) is going to be burned in place of coal and further “assumed” that three-fourths of it would not come from dedicated crops like switchgrass.

Nearly three-fourths of the biomass feedstock was predicted to come from wastes and residues (which were assumed to have no incremental land-use impacts), the remaining biomass supply was assumed to be derived from switchgrass.

…requiring an estimated 44,000–88,000 km2 of land …By comparison, the total area used for corn production in 2009 in the United States was about 350,000 km2 (USDA 2010). Because biopower-related land use is estimated to be sizable, efforts are needed to assess the degree to which and conditions under which land is available to support such an expansion without undue competition with food production and other uses.

If it were economical to displace a meaningful amount of coal with biomass today we would already be doing so to lower electric bills or increase profit margins. Burning biomass for energy is an idea as old as walking on two legs. The 80% prediction would drop considerably if this assumption turns out significantly wrong because there would not be enough land left to grow any corn (of which 40% is already being turned into ethanol).

Today biomass accounts for about 1.3% of our energy mix. They need it to increase by an order of magnitude by 2050. From an air pollution perspective, biomass has little improvement over coal. And because of land displacement issues, it is also not necessarily much better in the GHG department. From a wildlife habitat displacement perspective, biomass is worse than coal. Recent studies in the journal Nature have suggested that the last thing humanity should be doing is asking more of the biosphere.

Also, like squeezing water from one end of a balloon to another, using biomass for electricity would preclude the increased use of biomass for things like home heating (community boilers) and transportation (assuming that cellulosic will ever actually become commercially viable), not that using biomass for this is a good idea either.

Removing biomass from the list as well as hydro would drop the percentage of energy for electricity and in total to 53% and 21% respectively.

The study looked at scenarios ranging from 30% to 90% and made no attempt to assign probabilities or costs. In other words, the odds that the 80% 53% scenario will come to fruition may approach zero. The study is largely a wish list of what it would take for this to happen. However, any study that tries to predict what our energy mix will be 40 years into the future has to make a rather large number of assumptions.

Lastly, as a long-term analysis, uncertainties associated with assumptions and data, along with limitations of the modeling capabilities, contribute to significant uncertainty in the implications reported.

Right …significant uncertainty. To wit, I stopped counting at 500, the instances of the words “assume,” “assumed.” and “assumption” in just the first volume of this four volume study. I also counted over a hundred instances of the words “uncertain” and “uncertainty” and fifty five instances of “likely” or “likelihood” in that first volume.

Over the last twenty years renewable energy has gone from being 11% of our energy mix to 10%. Doing my own study, hang on a minute …a linear extrapolation of that trend would suggest that in 2050 only 8% of our energy will be renewable.

Just about every study I’ve read on this topic over the last decade has suggested that wind and solar combined (cost issues aside) can provide a maximum of roughly 35% of our electric power quite simply because the sun does not always shine and the wind does not always blow, particularly when we would need them to do so–on windless nights for example.

The NREL study pulled out the stops and managed to increase that 35% potential of wind and solar by roughly 15% for a total of 50%. As I often point out, I’m a big fan of solar so I was a little disappointed to see that wind will be providing about three-fourths of that 50% (wind 37%, solar 13%). This would require an increase in wind energy from about half of a percent to 37 percent in 40 years …a 7500% increase. An increase of this magnitude would have to be done very carefully or it will be a disaster for some bird species. See this recent article in Nature titled The trouble with turbines: An ill wind:

“There are species of birds that are getting killed by wind turbines that do not get killed by autos, windows or buildings,” says Shawn Smallwood, an ecologist who has worked extensively in Altamont Pass, California, notorious for its expansive wind farms and raptor deaths. Smallwood has found that Altamont blades slay an average of 65 golden eagles a year. “We could lose eagles in this country if we keep on doing this,” he says.

Because this study was meant to see how much renewable energy could be incorporated it did not assume that any new nuclear power would be built. Interestingly enough the study also shows that about forty years from now existing nuclear power plants that have not reached retirement age would still be contributing more power than photovoltaic or concentrated solar. However, because the study did not account for the building of any new nuclear that would replace coal, coal is also still being used, also producing more power than photovoltaic or concentrated solar. It would have been smarter to replace that coal with nuclear. In their 80% renewable scenario, combined, photovoltaic and concentrated solar make up about 13% of the mix, coal and nuclear combined make up about 17%.

The scenarios described above—the Low-Demand Baseline scenario, the exploratory scenarios, and the six core 80% RE scenarios—were based on the low-demand assumptions, with overall electricity consumption that exhibits little growth from 2010 to 2050. To test the impacts of a higher-demand future, a scenario with the 80%-by-2050 renewable electricity generation but a higher end-use electricity demand was evaluated, with demand in 2050 30% higher than in the low-demand scenarios.

Wait a minute. The population of the United States is expected to grow by 37 percent by 2050. Demand for electricity will only grow 30 percent? Holding electric power growth at 30% would preclude the use of electricity (in place of oil) for things like transportation, heating, industry, again squeezing energy from one end of the balloon to the other. I drive an electric car which increased my electric bill about 30%. The Midwest is experiencing record heat waves. Assuming this is going to be a trend as a result of global warming we may experience higher air conditioning loads. My brother, who lives in the Midwest, expects his electric bill this month to top $300. Do the math.

Interestingly enough, the word nuclear was used just over eighty times in the first volume which is surprising considering that the study was about renewable energy. The study claims that this 80% renewable scenario would cost no more than has been predicted by preceding studies about future use of low carbon energy sources …which include nuclear:

These studies generally considered a portfolio of clean generation technology options, including renewable, nuclear, and low emissions fossil. The estimated incremental price impacts of the core 80% RE scenarios are comparable to these estimates.

But the next quote demonstrates a bias against nuclear:

The future cost of nuclear power plants as well as power plants using CCS is particularly uncertain.

As if the future cost of renewables is not uncertain? How bizarre to compare an untested hypothesis like coal carbon capture and sequestration (CCS) with nuclear which has a proven track record of producing about 20% of our electricity for about half of a century at very competitive prices. There are also many improved versions of nuclear power in the pipeline that have great potential to reduce its high upfront costs and already unprecedented safety while maintaining its proven long-term cost effectiveness. The future cost is just as likely to go down as up.

As is typical, coal and nuclear are usually mentioned together in the report even though one dumps mountain ecosystems into creek ecosystems and uses the atmosphere as an open sewer, while the other has the same carbon footprint as solar power.

Achieving 80% renewable electricity would require considerable transmission investment

I strongly suspect that this will prove to be a gross understatement. Cost effectively distributing Southwest sun and Midwest wind to the coasts of the North American continent while integrating it into the grid is not going to be easy or cheap. To get there from here they acknowledge that we will need:

…increased electric system flexibility, needed to enable electricity supply-demand balance with high levels of renewable generation, can come from a portfolio of supply- and demand-side options, including flexible conventional generation, grid storage, new transmission, more responsive loads …

But most of these things would improve the efficiency of conventional power generation as well. Storage will have to increase 400% above their baseline to compensate for wind and solar intermittency. Again, if that assumption turns out to be significantly off, the percentage of renewable takes yet another hit.

The study assumed that nuclear can’t ramp up and down fast enough to compensate for wind and solar. In reality, there is no reason energy from a nuclear plant can’t be stored in a similar manner to wind and solar energy for rapid release when needed when the wind stops or clouds arrive. Energy storage is rarely done today because it is expensive, regardless of whether it comes from wind, solar, or nuclear. If new technology arrives in the future to make storage cheaper, it will enhance nuclear’s cost effectiveness to vary power output as well as other energy sources.

The next time you hear a commenter claim that all of our energy must eventually be renewable because we will eventually run out of fossil fuels and uranium ore, point back to this article and explain that it can’t all be renewable, nor does it have to be. What it has to be is affordable, with enough reserve to last long enough for humanity to find a replacement, and relatively environmentally benign. New hydro (which doesn’t even fit my definition of renewable) and biomass are worse than most fossil fuels when it comes to ecosystem impact.

If it were not for climate change and ocean acidification, fossil fuels would fit that bill. That leaves only three energy sources on the table: wind, solar, and nuclear (baseload, load following, and peaking versions–with storage and air cooled options available at extra cost).