The giant rotating blades of wind turbines and the bluish-black panels of rooftop solar-power systems have become a familiar sight in many countries. It might seem there’s little to stop them from quickly becoming as commonplace throughout the world as petrol stations and power lines. But is that so? Two energy experts have considered this question for a new thought-provoking publication called “The colours of energy”. Their insights into the scales involved put things into perspective.
Sun, sun everywhere
In 2014, about 1% of all electricity consumed on earth – just under 200 terawatt-hours – came from the sun. But for solar energy to make an impact on the scale of today’s oil and gas industry, it would have to generate about 100 times more electricity in the future, says Wim Sinke, Manager Programme Development at ECN Solar Energy in the Netherlands and Professor of Photovoltaic Energy Conversion at the University of Amsterdam. And if sun-generated electricity did grow hundred-fold, it would not account for all of the world’s electricity. That’s because by the time it had reached that goal, the amount of electricity consumed by the world will have at least doubled.
But, Sinke notes, an intermediate goal of 5% of global electricity consumption by the early 2020s is well within the solar industry’s grasp. It certainly does not depend on any new technology breakthrough in photovoltaic cells – the light-to-electricity convertors in solar panels. “Photovoltaics is the breakthrough,” Sinke writes.
So what’s preventing solar power from going further, reaching, say, 25% of consumed electricity? “If photovoltaic technology is going to provide terawatts of electricity, it will be literally everywhere,” says Sinke. And would omnipresent solar panels be politically and socially acceptable throughout the world? Reaching a 25% share of the global power generation with the light-to-electricity conversion efficiency of current photovoltaic cells, for example, “would require areas comparable to the total net area available on roofs and facades.”
Sinke believes that if photovoltaic technology is going to be present on such a large scale, we have to make sure that people like it. “The biggest mistake is to take public and political support for granted,” he warns. Systems that can be nicely integrated into the urban landscape should be considered a “necessary building block for very large-scale use and a requirement for societal acceptance,” argues Sinke.
Out of sight, but not out of mind
Wim Thomas, Shell’s Chief Energy Adviser, considers a similar question as Sinke’s. He wonders what it would take society to put a really big wind farm offshore – one big enough to meet most of the Netherlands’ energy needs.
He concludes that it would require a vast network of 34,300 wind turbines spread over 12,000 square kilometres of the North Sea. (For comparison: a natural-gas project that yields a comparable amount of electricity would need a few hundred wells and a couple of processing plants and power stations, taking up a few square kilometres in total.)
And the wind megaproject’s total price? More than €360 billion – and that’s only for the 20-year Phase 1. But after considering ways to deal with the many political, societal, financial and economic issues, Thomas comes to the conclusion that it is “not necessarily unachievable or unaffordable” to expand renewable energy to reach the scale of oil and gas. After all, the Netherlands has some powerful motivation – longer-term energy self-sufficiency and the end of carbon dioxide emissions, to name a couple.
Storing energy for a sunless, windless day
But the sun and the wind are as variable as the weather. So the power they generate when they are at their strongest must be stored for when they are not around. Both Wims point out that this surplus power could best be stored as hydrogen, which can serve as transport fuel. Thomas estimates that his conceptual megaproject would need to convert about a fifth of all the electricity produced into hydrogen.
And in that case, the mega project’s impact on the Dutch transport infrastructure would be dramatic – and impossible to hide. Hydrogen-powered cars would account for a third of all kilometres driven. And they will need a whole new national fuel distribution network.
Energy from renewables is rapidly becoming an important part of the global energy mix. But as both writers make clear, shifts to truly global-scale solar and wind will require a vast mobilisation of political willpower and monetary resources.
This was first published on Shell’s website as part of a free e-book compiling essays on the future of energy in society. Read more here.
By : Shell