00:06 Every year, the world uses 35 billion barrels of oil.
00:11 This massive scale of fossil fuel dependence pollutes the Earth and it won’t last forever.
00:18 Scientists estimate that we’ve consumed about 40% of the world’s oil.
00:23 According to present estimates, at this rate, we’ll run out of oil and gas in 50 years or so, and in about a century for coal.
00:32 On the flip side, we have abundant sun, water, and wind.
00:36 These are renewable energy sources, meaning that we won’t use them up over time.
00:41 What if we could exchange our fossil fuel dependence for an existence based solely on renewables?
00:48 We’ve pondered that question for decades, and yet, renewable energy still only provides about 13% of our needs.
00:55 That’s because reaching 100% requires renewable energy that’s inexpensive and accessible.
01:02 This represents a huge challenge, even if we ignore the politics involved and focus on the science and engineering.
01:10 We can better understand the problem by understanding how we use energy.
01:14 Global energy use is a diverse and complex system, and the different elements require their own solutions.
01:21 But for now, we’ll focus on two of the most familiar in everyday life: electricity and liquid fuels.
01:28 Electricity powers blast furnaces, elevators, computers, and all manner of things in homes, businesses, and manufacturing.
01:36 Meanwhile, liquid fuels play a crucial role in almost all forms of transportation.
01:43 Let’s consider the electrical portion first.
01:45 The great news is that our technology is already advanced enough to capture all that energy from renewables, and there’s an ample supply.
01:54 The sun continuously radiates about 173 quadrillion watts of solar energy at the Earth, which is almost 10,000 times our present needs.
02:05 It’s been estimated that a surface that spans several hundred thousand kilometers would be needed to power humanity at our present usage levels.
02:14 So why don’t we build that?
02:16 Because there are other hurdles in the way, like efficiency and energy transportation.
02:21 To maximize efficiency, solar plants must be located in areas with lots of sunshine year round, like deserts.
02:30 But those are far away from densely populated regions where energy demand is high.
02:36 There are other forms of renewable energy we could draw from, such as hydroelectric, geothermal, and biomasses, but they also have limits based on availability and location.
02:47 In principle, a connected electrical energy network with power lines crisscrossing the globe would enable us to transport power from where it’s generated to where it’s needed.
02:59 But building a system on this scale faces an astronomical price tag.
03:03 We could lower the cost by developing advanced technologies to capture energy more efficiently.
03:09 The infrastructure for transporting energy would also have to change drastically.
03:14 Present-day power lines lose about 6-8% of the energy they carry because wire material dissipates energy through resistance.
03:23 Longer power lines would mean more energy loss.
03:27 Superconductors could be one solution.
03:30 Such materials can transport electricity without dissipation.
03:34 Unfortunately, they only work if cooled to low temperatures, which requires energy and defeats the purpose.
03:41 To benefit from that technology, we’d need to discover new superconducting materials
03:46 that operate at room temperature.
03:49 And what about the all-important, oil-derived liquid fuels?
03:53 The scientific challenge there is to store renewable energy in an easily transportable form.
03:59 Recently, we’ve gotten better at producing lithium-ion batteries, which are lightweight and have high-energy density.
04:07 But even the best of these store about 2.5 megajoules per kilogram.
04:12 That’s about 20 times less than the energy in one kilogram of gasoline.
04:17 To be truly competitive, car batteries would have to store much more energy without adding cost.
04:23 The challenges only increase for bigger vessels, like ships and planes.
04:28 To power a cross-Atlantic flight for a jet, we’d need a battery weighing about 1,000 tons.
04:35 This, too, demands a technological leap towards new materials, higher energy density, and better storage.
04:43 One promising solution would be to find efficient ways to convert solar into chemical energy.
04:49 This is already happening in labs, but the efficiency is still too low to allow it to reach the market.
04:55 To find novel solutions, we’ll need lots of creativity, innovation, and powerful incentives.
05:02 The transition towards all-renewable energies is a complex problem involving technology, economics, and politics.
05:10 Priorities on how to tackle this challenge depend on the specific assumptions we have to make when trying to solve such a multifaceted problem.
05:19 But there’s ample reason to be optimistic that we’ll get there.
05:23 Top scientific minds around the world are working on these problems and making breakthroughs all the time.
05:29 And many governments and businesses are investing in technologies that harness the energy all around us.