字幕表 動画を再生する 英語字幕をプリント Iceland: the land of majestic waterfalls, black sands, sparkling glaciers, and... maybe one of the world’s wildest solutions for solving climate change? Nestled beside the majestic hills of southwestern Iceland, are a series of huge pods capable of taking CO2 that's been snatched from the air and injecting it into underground stones, where the gas can be stored safely for millenia. And yes, this might sound like the stuff of science fiction, but it’s all real, and it’s actually happening. Just so we’re clear, our planet is heating up, and fast. CO2 levels now exceed 415 parts per million, higher than they’ve ever been in the past 800,000 years. And while there’s dispute over what number constitutes a dangerous threshold, there is consensus that those levels must drop to avoid imminent catastrophic warming. The Intergovernmental Panel on Climate Change, or IPCC, estimates that by the end of the century we must pull at least 100 gigatons of CO2 and as much as 1,000 gigatons of CO2 from the atmosphere. Which, to put that into perspective, is the equivalent of 20 years worth of global greenhouse gas emissions. So now you’re probably thinking the same thing that I’m thinking: HOW are we going to accomplish that?! Well, in addition to the rapid adoption of renewable energy and wide-scale reforestation, the IPCC maintains that carbon dioxide removal technologies will be critical to tackling climate change. And that’s where direct air capture, or DAC technology, comes into play. This idea of pulling CO2 directly from the air has actually been around for well over a decade, but it’s only been in the past few years that this tech has really come into its own. DAC works by redirecting carbon dioxide from the atmosphere and placing it somewhere more benign. Like inside rocks. At least, that’s what Climeworks has been doing at its plant in Iceland since operations began in late 2017. The machine consists of a single collector that's able capture CO2 straight from the air using reusable filters. As air is drawn into the plant, the CO2 molecules within it chemically bind to filter materials. The filter is then heated up to about 100°C, causing the CO2 molecules to unstick from the filter and collect as concentrated gas. This gas is then mixed with water and injected underground, where it reacts with basalt to become stone in under two years. Meanwhile, the CO2-free air is sent back from whence it came, and the cycle repeats. While removing 2,500 metric tons of CO2 from the atmosphere and safely storing it beneath the Earth is one use, Climeworks is also demonstrating captured carbon’s ability to transform into methane that can be used to power cars, like at its plant in Italy. And over in Switzerland, a waste incineration site supplies power to their their DAC plant, which funnels captured carbon into nearby greenhouses to ripen vegetables. By demonstrating captured carbon’s many uses, Climeworks has managed to become the first-ever DAC company to go commercial. The company also excitedly claims that its technology is a negative emissions solution, meaning that more carbon is being moved from the biosphere to the geosphere than the other way around. But there’s some question over whether or not this technology can truly be effective. Right off the bat, it’s clear that it must be massively scaled up if it’s ever going to make a dent in the 1,000 gigatons of CO2 that we have to scrub from the air. While the Climeworks plant in Switzerland is capable of capturing 900 metric tons of CO2 annually, the biggest concern is the fairly substantial energy expenditures needed to extract all that CO2 from the air in the first place. According to company estimates, the scaled up process will use about 2,000 KWh of heat and 650 KWh of electricity per metric ton of CO2. By sequestering carbon onsite and using renewable energy from nearby geothermal plants, the Iceland operation intends to lessen its carbon-footprint...but all of this still makes you wonder how we define ‘negative emissions.’ Climeworks has set a goal to eliminate about 400 million metric tons of CO2—or about 1% of global emissions—by 2025, banking on carbon’s increasing value as a trading commodity that can help potential buyers, like energy companies and countries, meet climate targets. But it’s still just a 1% reduction, so it’s clear that while technologies, like Climeworks' solutions, are really cool, they can't tackle climate change alone. And the race to find more solutions is still very much on. Do you think that this carbon-capture technology can really make a dent in removing atmospheric carbon? Let us know in the comments below. And don’t forget to subscribe for more Seeker. As always, thanks for watching and we'll see you next time.