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Environment

Aug 19, 2019

Should we Turn the Sahara Desert into a Huge Solar Farm?

According to NASA estimates, each Saharan square metre receives, on average, between 2,000 and 3,000-kilowatt hours of solar energy per year, a farm would be equivalent to 36 billion barrels of oil.

WRITTEN BY

Amin Al-Habaibeh

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 US. 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.


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This article was updated on April 30 to correct an error. Saharan solar could potentially produce more than seven thousand times the electricity requirements of Europe (not 7).The Conversation

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.

Cover photo: Photo by Arthur Aldyrkhanov on Unsplash

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Environment

Sep 17, 2019

India Must Stop Deforesting its Mountains if it Wants to Fight Floods.

During floods and landslides in August 2019, two villages were completely destroyed killing several people, while a year earlier Kerala saw its worst floods in a century.

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WRITTEN BY

Gayathri D Naik

Floods are now an annual nightmare in many parts of southern and western India. Valleys in the states of Maharashtra, Karnataka and Kerala that weren’t considered flood-prone until recently are at risk.

These floods appear to be getting more severe. Climate change is causing stronger and more erratic rainfall with recurrent floods in low-lying areas while population growth is putting more people in risky areas. And another problem comes from deforestation in the mountain range where much of the water first fell: the Western Ghats.

More than 500 people died in severe flooding in Kerala in 2018.
AJP / shutterstock

The Western Ghats run for 1,600km in parallel with India’s west coast, from Gujarat right down to Tamil Nadu at the tip of the subcontinent. It is – or was – a picturesque landscape of serene valleys, steep gorges and virgin forests. Yet recurring floods and landslides in the mountains, hills and areas downstream (between the Ghats and the sea) show that India must rethink its environmental law to balance the needs of nature and humans.

The Western Ghats follow India’s western coast.
Nichalp / wiki, CC BY-SA

The mountains are teeming with life. Though they cover only a small part of India’s total land area, the Ghats are home to more than 30% of the country’s species of plants, fish, reptiles, birds and mammals, including both wild elephants and tigers. Its combination of unique species and habitat loss means Unesco has recognised it as one of eight global “hottest hotspots” of biodiversity.

Climate change is already having an obvious impact, with unprecedented rains in monsoon seasons and severe drought and dry rivers in summer. And as the human population has grown, people have chopped down the forests and replaced them with spice, tea, coffee and rubber plantations. Thousands of illegal stone quarries now also operate in the Ghats, where mountainsides are demolished to generate stones and sand for the construction industry. Deforestation and the use of highly destructive explosives mean these areas are prone to increased seismic tremors and landslides.

Large dams on major rivers offer renewable energy yet also raise another set of environmental problems. In Kerala, many are located in eco-sensitive parts of the Western Ghats, with some dating back to British rule. As demand for energy increases, India plans to build more dams which in turn could lead to massive deforestation and ecosystem destruction. All this makes flooding more severe, as deforestation in the catchment area of a river reduces the land’s ability to retain water.

Tea plantation on deforested land near Munnar, Kerala, in the Western Ghats.
Mazur Travel / shutterstock

Whether triggered by damming, deforestation, or exacerbated by climate change, human-induced natural disasters in the region have pointed to a need for stronger environmental protection laws.

How to protect the Western Ghats

India’s 1950 constitution claims that protection of environment is a fundamental duty of every citizen, and though it does not explicitly contain a right to a clean environment, legal authority for environmental lawmaking is derived from the document.

Over the years, the country’s central government has enacted various laws that are applicable to the Western Ghats: the Environment Protection Act 1986, the Forest Conservation Act 1980, the Biodiversity Conservation Act 2002 and so on. However, these laws are not implemented efficiently, which makes me wonder if areas like the Himalayas and the Western Ghats – internationally significant ecosystems and biosphere reserves – need their own special laws.

The endangered Boulenger’s tree frog is found in the Western Ghats – and nowhere else.
lensalot / shutterstock

Additionally, India’s water laws are inadequate. Existing legislation primarily focuses on pollution control, meaning the law has little to say about preventing or even managing floods which result from mismanagement of dams or too much riverside development.

The problem is enhanced in case of rivers that flow across state boundaries. Some of the major floods in the past couple years happened after dams at or near full capacity in one district or state were opened, letting water flow downstream into another area. Recently, a draft dam safety bill has been proposed to address these problems.

Similarly, discussions over climate change and environmental lawmaking should involve more grassroot level participation. For most people, poverty and earnings still matter more than climate mitigation or adaptation. Hence people’s perception should be moulded to recognise and realise how deforestation or climate change impacts their daily life.

The Western Ghats are south India’s lifeline, with millions dependent on the range either directly or indirectly. These mountains need protection. However, while new development in the region continues to be human-centric, the entire concept of nature preservation is relegated. To protect the Western Ghats, what we require is an attitude that recognises the significance of these mountains, and that will involve specific laws.The Conversation

Gayathri D Naik, Research Scholar, School of Law, SOAS, University of London

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Cover Photo: Mountains above Munnar, a hill town in Kerala, India. Santhosh Varghese / Shutterstock

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