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The theory of renewable energy sources being able to provide 100% of our power needs has gone from intriguing academic conundrum to evermore urgent necessity in the last few decades. And with new feasibility studies and recent advances in technology, we could well be on the cusp of making it happen.
The devastating impact fossil fuels have had on the planet and its population are well understood. Worldwide air pollution kills an estimated four to seven million people each year, with many hundreds of millions more contracting serious illness. Carbon emissions are the main driver of climate change and the finite quantities of coal, gas and oil, and their subsequent price increases, cause economic, social and political instability.
It is a situation that cannot continue indefinitely, and a switch to clean power is the obvious alternative, but to fully harness the benefits of renewable energy sources, how much land needs to be sacrificed?
It is commonly agreed that in the race to supply the world with completely renewable energy, solar and wind are going to have to do most of the heavy lifting.
Every hour, more power from the sun hits the Earth than we can use in an entire year—yet it remains a seriously underutilised resource. Even with the recent ‘sun rush’ in the U.S and China, which saw both countries increase their amount of solar power by around 50%, it accounts for only about 4% of worldwide electricity demand. So, with that figure in mind, what are the chances of the sun being able to satisfy all the planet’s power needs?
A U.S Department of Energy report from 2009 estimated the global consumption of energy, in all its forms, reaching 678 quadrillion Btu by 2030—around a 40% increase on today. Working off current solar technology running at 20% efficiency, and with an average of 70% sunshine days per year, it would take an area of solar panels covering 496,805 square kilometres to meet the annual usage. To put that in perspective, it is about the size of Spain.
While that may seem like an unrealistic amount of land to give over to solar energy production, in reality, it is comparatively small. If we take America as an example, the world’s biggest consumer of energy, their projected 2050 power needs across the entire country could be met with roughly 33,000 square kilometres of solar panels. If the production was concentrated in just the sunniest territories, that figure drops to only 12,000 square kilometres.
To even further reduce the land usage, instead of building massive solar farms in the country’s deserts or across undeveloped areas, and instead siting them on rooftops, car parks and other commercial and industrial land, the required energy could be produced without significantly increasing the current land use footprint at all.
Wind farms cover a far larger area than a similarly productive solar farm. To supply the world’s current energy demands, around 21,000 terawatt-hours, it would take approximately four million turbines, spread across an expanse about half the size of Alaska.
But, according to a study from the National Renewable Energy Laboratory, the amount of land taken completely out of use by the presence of a wind farm only amounts to around 1% of the entire area the wind farm covers.
Turbines can be situated on otherwise productive farming, grazing and agricultural land, sharing the space with little to no impact. Even factoring in the additional requirements for access roads, substations, transmission lines and the temporary needs for construction, adds just a further 2% to the total.
Interestingly, wind turbines are even more efficient than solar farms, averaging 30% productivity rather than 20%. Advances in technology and the physical size of the turbines are starting to both increase that level of efficiency as well as lower the expenditure—the cost of developing the infrastructure has dropped by 90% since the 1980s.
With turbines being built taller than ever, and with more installed in off-shore wind farms which can offer three times the amount of power than those on land, the number and space needed for them will continue to drop.
For the first time, being able to meet all of our power needs with renewable energy is within reach. Along with solar and wind, hydroelectricity has been growing steadily for the last 40 years and now accounts for around 18% of global electricity generation. China, by far the biggest producer in the world, has more than tripled its output in the last decade, while Norway gets 98% of its energy from renewable sources, mostly hydropower.
All the most recent investigations suggest the relevant technology and the required land exists to be completely free from fossil fuels by 2050—bringing about a solution to global warming and air pollution.
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