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#04: Are renewables capable of providing enough energy for the world?

Sept. 4, 2020

So many people say we must abolish burning fossil fuels. But is that possible? Are renewable energy sources abundant enough to quench our ever-growing thirst for energy?
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After some intermission posts (or let's be honest: rants) about Covid-19, masks, and politics, I am back to writing about climate change and related topics. And I want to use the momentum I got from reading the book "Earth: The Operator's Manual" by renowned climatologist Prof Richard Alley. He is a geologist who is mainly working with ice cores and has a profound interest in history and historic means of energy generation. Also, he is a self-confessed US Republican, which is something that actually wouldn't be worth mentioning. But in today's US climate of extreme partisanship it often seems that all Democrats believe in human-caused global warming, while no Republican could ever jump on this "warming hoax train" (meanwhile, climate change itself remains completely apolitic and keeps on happening despite every partisan quarrel). So forgive me for pointing out that he is a Republican - he himself likes to make this point explicit, so I am just following his lead. Last but not least, Richard Alley is the spitting image of Prof. Hubert Farnsworth of Futurama, and I say this will all due respect for both of them. You will need to hear him talk though to see the resemblance, so I am presenting you his speech before congress, which is also worth seeing content-wise.

How much energy is a lot?

But let's come back to Prof Alley's favourite topic: energy! Because this will help me address the question that I am being asked pretty often: "How can people simply believe that we can completely leave energy from fossil fuels behind? Our energy consumption is huge and still rising. By the middle of the century we will be around 9 to 10 billion people on this planet, so energy consumption will be even much higher. We cannot provide energy for all these people with some sun rays and wind power. Besides what if the sun doesn't shine and the wind doesn't blow?" Ok... all of these assumptions are completely correct: We consume a lot of energy. In future we will consume even more energy. Also, we cannot produce energy from the sun or wind, if the former doesn't shine and the latter doesn't blow. But while these remarks are all correct, they are not very precise. And this may also prevent the drawn conclusion from being correct. As a scientist I want to know what the numbers are... "A lot" and "more than" or "not enough" is all very fuzzy. Fortunately, Prof. Alleys book gave me good scientific guidance on these issues.


But let's begin with a quote by Prof Alley that should stand in the beginning of all thoughts on employing sustainable energy sources and especially when examining the transition from fossil fuels to renewables:

"Be forwarned though - there is no single solution, except the inspiration and perspiration of a lot of people. All of the paths we might follow have costs as well as benefits. [...] No one really knows the best path to a sustainable-energy future yet, in part because we have been spending so much of our effort arguing about things that don't matter very much, rather than things that do matter."

Wait... what about the jobs?
Speaking of the possible costs of the energy transition, one of the main arguments against subscribing to sustainable energies is job loss. Fossil fuel companies are the employers of millions of people world wide, so this naturally causes concern. While this concern is understandable, many studies have shown that the transition from fossil fuels to sustainable sources will produce more jobs than it will take. For example, a $1 Million investment in wind or solar generated 40% more jobs over ten years than an equivalent investment in the coal industry (source: IPCC report 2007). Renewable energy investment and development tends to create more jobs than fossil fuel energy because a larger share of renewable energy expenditures go to manufacturing equipment, installation, and maintenance, all of which are typically more labor-intensive than extracting and transporting fossil fuels (see this study by UCSUSA). The same conclusions come from studies by Wei et al, Branker et al., Sastresa et al., and many others. It is a widespread myth that renewables kill jobs without creating even more new ones.

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Crunching the numbers

But let's come back to what I initially promised: looking at some proper numbers instead of losing yourself in terms as "it's so, so much energy!". How much energy do we actually consume on this planet as a whole? In 2012 (the time that Alley's book was written), humans consumed about 16 terawatts (TW) (source: US Energy Information Agency, EIA). By now, this may be a bit more and in the coming years this number will rise due to a growing world population as well as the progressing digitalisation in many fields of life, which will cause a higher average energy consumption per person. But whether we will soon consume 18 or 20 or even 25 TW is something that will become quickly negligible, after we have a look at the potential that renewable resources can offer us.

Blowing in the wind

Energy created from wind can provide us with 1.220 TW. Compare this to the number of our consumption and you will be pleasantly surprised. Regarding this number I do not even need to stress that this of course is a best-case scenario (taken from Lu et al.) and that we need to take several things into account when dealing with wind energy. Wind turbines are loud and they are large, their noise may be unpleasant for humans as well as wild-life. So the number needs to be corrected a bit since we are limited in the placement of the turbines. But this is still far from impossible. To quote Prof Alley:

"Imagine spacing 2.5 MW turbines in a land-based wind farm, just far enough apart so they don't block each other's wind very much. Do this on the plains and deserts of the world, avoiding cities, forests, glaciers, and lakes, and using only those places windy enough so the turbines average at least 20% of their capacity. Such a grid would generate more than five times the current energy use [...]. Larger turbines , and inclusion of offshore sites, would generate even more."

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We will not forget that the effort of wiring the world with wind power will not be easy. This is not a no-brainer, but technical difficulties can be overcome with enough research and investment in the energy resource. Fact is that wind power has enough potential to create enough energy for the world several times over.

Here comes the sun

But all the winds blush when compared to the potential of energy created by the sun. Potentially, we can create 173.000 TW of energy by the sun (remember our demand of around 16 TW worldwide?). How many solar modules would we require to harvest enough energy for our needs? Capturing just 10% of the sunshine reaching the surface in sunny places such as the Sahara or Yuma, Arizona, would provide at least 20 W/m² (see MacKay et al.). At this value, the world demand of energy could be supplied from a square area of 900 km on a side. The desert Southwest in the US alone has enough land suitable for solar power generation to supply more than 80% of the world use (see Fthenakis et al.). And don't forget other places like the Sahara or the Australian outback (next to all the solar modules we already have on other places of this world).

Wind and sun are the largest resources of sustainable energy that we know. But there are more which can be employed for our use: Energy created from plants (166 TW), waves and currents (65 TW), geothermal (44 TW) and hydroelectric (1.9 TW) sources, and tides (4 TW) offer more than enough potential to create a good mixture of sustainable resources to provide the whole planet with enough energy. Without fossil fuels. Some of these are peak powers, which can be switched on immensely quick, if the sun doesn't shine or the wind doesn't blow. Regarding these numbers I fortunately do not have to dig into the topic of nuclear power. This very polarised topic has very intelligent champions on both sides of the aisle and they all have good arguments. I am not informed enough to truly be able to give a good estimate on the necessity of energy created by nuclear plants. Yes, they do not produce emissions of greenhouse gases, that's very good. And yes, the question of security and removal of radioactive remnants is a very difficult one, that's very bad. I will leave it at that and only talk about stuff that I am confident with. Also, I am looking very forward to the prospects of nuclear fusion, which are finally getting closer to realisation in the implementation of ITER, world's largest nuclear fusion project. Although of course, we shouldn't treat fusion as a "get out of (climate change) jail" card, because the development will still take 3 decades or more.

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It's all in the mix

Coming back to Alley's initial quote: There is no one singular solution. And this is not due to the limitation of available resources, no, there is plenty of those. But it is due to the technical limitations that still exist in moving and storing the produced energy. Sun doesn't shine at night, wind doesn't blow all the time... but taken all the aforementioned resources together and as complementary resources which can switch on if another switches off, the provision of the world with sustainable energy is very possible. The generation, transport, storage, and maintenance of sustainable energies will be of huge economic value as well. Not to forget of the newly created jobs. Basically, it is up to us to harvest the abundant resources. Or to put it in the words of Soren Hermansen, Director of Samso Energy Academy: "Technology is easy. We find solutions... it's a matter of making decisions. "


If you are interested in the topic, you can either read Prof. Alley's "Earth: The Operators' Manual" or you can watch the documentary mini-series of the same name, all readily and publicly available on the website of EtOM.

Picture references, respectively: Pixabay, Gustavo Fring (really?), Laura Penwell, Pixabay again