- If the Sahara Desert were a country, it would be the fifth largest in the world.
- Each square metre receives, on average, between 2,000 and 3,000 kilowatt hours of solar energy per year.
- There are two practical technologies at the moment to generate solar electricity within this context: concentrated solar power (CSP) and regular photovoltaic solar panels.
Whenever I visit the Sahara I am struck by how sunny and hot it is and how clear the sky can be.
Aside from a few oases there is little vegetation, and most of the world's largest desert is covered with rocks, sand and sand dunes. The Saharan sun is powerful enough to provide Earth with significant solar energy.
The statistics are mind-boggling. If the desert were a country, it would be fifth biggest in the world — it's larger than Brazil and slightly smaller than China and the U.S. Each square metre receives, on average, between 2,000 and 3,000 kilowatt hours of solar energy per year, according to NASA estimates. Given the Sahara covers about 9m km², that means the total energy available – that is, if every inch of the desert soaked up every drop of the sun's energy — is more than 22 billion gigawatt hours (GWh) a year.
This is again a big number that requires some context: it means that a hypothetical solar farm that covered the entire desert would produce 2,000 times more energy than even the largest power stations in the world, which generate barely 100,000 GWh a year. In fact, its output would be equivalent to more than 36 billion barrels of oil per day — that's around five barrels per person per day. In this scenario, the Sahara could potentially produce more than 7,000 times the electricity requirements of Europe, with almost no carbon emissions.
Global horizontal irradiation, a measure of how much solar power received per year. (Global Solar Atlas / World Bank)
What's more, the Sahara also has the advantage of being very close to Europe. The shortest distance between North Africa and Europe is just 15km at the Strait of Gibraltar. But even much further distances, across the main width of the Mediterranean, are perfectly practical — after all, the world's longest underwater power cable runs for nearly 600km between Norway and the Netherlands.
Over the past decade or so, scientists (including me and my colleagues) have looked at how desert solar could meet increasing local energy demand and eventually power Europe too – and how this might work in practice. And these academic insights have been translated in serious plans. The highest profile attempt was Desertec, a project announced in 2009 that quickly acquired lots of funding from various banks and energy firms before largely collapsing when most investors pulled out five years later, citing high costs. Such projects are held back by a variety of political, commercial and social factors, including a lack of rapid development in the region.
The planet Tatooine from the Star Wars movies was filmed in southern Tunisia. (Amin Al-Habaibeh, Author provided)
More recent proposals include the TuNur project in Tunisia, which aims to power more than 2m European homes, or the Noor Complex Solar Power Plant in Morocco which also aims to export energy to Europe.
Two technologies
There are two practical technologies at the moment to generate solar electricity within this context: concentrated solar power (CSP) and regular photovoltaic solar panels. Each has its pros and cons.
Concentrated solar power uses lenses or mirrors to focus the sun's energy in one spot, which becomes incredibly hot. This heat then generates electricity through conventional steam turbines. Some systems use molten salt to store energy, allowing electricity to also be produced at night.
A concentrated solar plant near Seville, Spain. The mirrors focus the sun's energy on the tower in the centre. (Novikov Aleksey / shutterstock)
CSP seems to be more suitable to the Sahara due to the direct sun, lack of clouds and high temperatures which makes it more efficient. However the lenses and mirrors could be covered by sand storms, while the turbine and steam heating systems remain complex technologies. But the most important drawback of the technology is its use of scarce water resources.
Photovoltaic solar panels instead convert the sun's energy to electricity directly using semiconductors. It is the most common type of solar power as it can be either connected to the grid or distributed for small-scale use on individual buildings. Also, it provides reasonable output in cloudy weather.
But one of the drawbacks is that when the panels get too hot their efficiency drops. This isn't ideal in a part of the world where summer temperatures can easily exceed 45℃ in the shade, and given that demand for energy for air conditioning is strongest during the hottest parts of the day. Another problem is that sand storms could cover the panels, further reducing their efficiency.
Both technologies might need some amount of water to clean the mirrors and panels depending on the weather, which also makes water an important factor to consider. Most researchers suggest integrating the two main technologies to develop a hybrid system.
Just a small portion of the Sahara could produce as much energy as the entire continent of Africa does at present. As solar technology improves, things will only get cheaper and more efficient. The Sahara may be inhospitable for most plants and animals, but it could bring sustainable energy to life across North Africa – and beyond.
Amin Al-Habaibeh, Professor of Intelligent Engineering Systems, Nottingham Trent University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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- Map details dramatic shift from CNN to Fox News over 10-year period
- Does it show the triumph of "fake news" — or, rather, its defeat?
- A closer look at the map's legend allows for more complex analyses
Dramatic and misleading
Image: Reddit / SICResearch
The situation today: CNN pushed back to the edges of the country.
Over the course of no more than a decade, America has radically switched favorites when it comes to cable news networks. As this sequence of maps showing TMAs (Television Market Areas) suggests, CNN is out, Fox News is in.
The maps are certainly dramatic, but also a bit misleading. They nevertheless provide some insight into the state of journalism and the public's attitudes toward the press in the US.
Let's zoom in:
- It's 2008, on the eve of the Obama Era. CNN (blue) dominates the cable news landscape across America. Fox News (red) is an upstart (°1996) with a few regional bastions in the South.
- By 2010, Fox News has broken out of its southern heartland, colonizing markets in the Midwest and the Northwest — and even northern Maine and southern Alaska.
- Two years later, Fox News has lost those two outliers, but has filled up in the middle: it now boasts two large, contiguous blocks in the southeast and northwest, almost touching.
- In 2014, Fox News seems past its prime. The northwestern block has shrunk, the southeastern one has fragmented.
- Energised by Trump's 2016 presidential campaign, Fox News is back with a vengeance. Not only have Maine and Alaska gone from entirely blue to entirely red, so has most of the rest of the U.S. Fox News has plugged the Nebraska Gap: it's no longer possible to walk from coast to coast across CNN territory.
- By 2018, the fortunes from a decade earlier have almost reversed. Fox News rules the roost. CNN clings on to the Pacific Coast, New Mexico, Minnesota and parts of the Northeast — plus a smattering of metropolitan areas in the South and Midwest.
"Frightening map"
Image source: Reddit / SICResearch
This sequence of maps, showing America turning from blue to red, elicited strong reactions on the Reddit forum where it was published last week. For some, the takeover by Fox News illustrates the demise of all that's good and fair about news journalism. Among the comments?
- "The end is near."
- "The idiocracy grows."
- "(It's) like a spreading disease."
- "One of the more frightening maps I've seen."
- "LOL that's what happens when you're fake news!"
- "CNN went down the toilet on quality."
- "A Minecraft YouTuber could beat CNN's numbers."
- "CNN has become more like a high-school production of a news show."
Not a few find fault with both channels, even if not always to the same degree:
- "That anybody considers either of those networks good news sources is troubling."
- "Both leave you understanding less rather than more."
- "This is what happens when you spout bullsh-- for two years straight. People find an alternative — even if it's just different bullsh--."
- "CNN is sh-- but it's nowhere close to the outright bullsh-- and baseless propaganda Fox News spews."
"Old people learning to Google"
Image: Google Trends
CNN vs. Fox News search terms (200!-2018)
But what do the maps actually show? Created by SICResearch, they do show a huge evolution, but not of both cable news networks' audience size (i.e. Nielsen ratings). The dramatic shift is one in Google search trends. In other words, it shows how often people type in "CNN" or "Fox News" when surfing the web. And that does not necessarily reflect the relative popularity of both networks. As some commenters suggest:
- "I can't remember the last time that I've searched for a news channel on Google. Is it really that difficult for people to type 'cnn.com'?"
- "More than anything else, these maps show smart phone proliferation (among older people) more than anything else."
- "This is a map of how old people and rural areas have learned to use Google in the last decade."
- "This is basically a map of people who don't understand how the internet works, and it's no surprise that it leans conservative."
A visual image as strong as this map sequence looks designed to elicit a vehement response — and its lack of context offers viewers little new information to challenge their preconceptions. Like the news itself, cartography pretends to be objective, but always has an agenda of its own, even if just by the selection of its topics.
The trick is not to despair of maps (or news) but to get a good sense of the parameters that are in play. And, as is often the case (with both maps and news), what's left out is at least as significant as what's actually shown.
One important point: while Fox News is the sole major purveyor of news and opinion with a conservative/right-wing slant, CNN has more competition in the center/left part of the spectrum, notably from MSNBC.
Another: the average age of cable news viewers — whether they watch CNN or Fox News — is in the mid-60s. As a result of a shift in generational habits, TV viewing is down across the board. Younger people are more comfortable with a "cafeteria" approach to their news menu, selecting alternative and online sources for their information.
It should also be noted, however, that Fox News, according to Harvard's Nieman Lab, dominates Facebook when it comes to engagement among news outlets.
CNN, Fox and MSNBC
Image: Google Trends
CNN vs. Fox (without the 'News'; may include searches for actual foxes). See MSNBC (in yellow) for comparison
For the record, here are the Nielsen ratings for average daily viewer total for the three main cable news networks, for 2018 (compared to 2017):
- Fox News: 1,425,000 (-5%)
- MSNBC: 994,000 (+12%)
- CNN: 706,000 (-9%)
And according to this recent overview, the top 50 of the most popular websites in the U.S. includes cnn.com in 28th place, and foxnews.com in... 27th place.
The top 5, in descending order, consists of google.com, youtube.com, facebook.com, amazon.com and yahoo.com — the latter being the highest-placed website in the News and Media category.
