字幕表 動画を再生する 英語字幕をプリント My solution to most of my problems is to light them on fire. Why can’t garbage be one of those problems? HI, I’m Julian, this is DNews. Americans make a lot of trash, according to the EPA in 2012 the average person made 1,600 pounds of solid waste that year, about 45% more than the average european. About 55% of that goes in a landfill, so to translate that, if you’re an average american, you were responsible for burying 880 pounds of trash in 2012. Is there something that garbage could be doing besides just sitting there? Sweden thinks so. Only about 1% of swedish trash ends up in a landfill. The rest is almost evenly split between being recycled and burned for energy. Sweden actually burns so much trash they import 700,000 tons of it from europe in order to keep the fires lit, and by using the heat to create steam and run turbines, they get about 8.5% of their electricity needs from burning waste. Göran Skoglund, a representative of one of Sweden’s energy companies, estimates that burned trash has about a third the energy pound for pound as burned fossil fuels. Burning their trash means they save space in landfills, don’t need to import fossil fuels, and as an added bonus, they cut down on greenhouse gasses. Alright, stop right there because I know exactly what you all just yelled at your computer screens. “But Julian, burning anything is going to create CO2!” And yeah, you’re right. But like a Swedish police drama, it’s all very nuanced. On the face of it, burning garbage actually looks less favorable than coal or natural gas, in terms of CO2 production. According to the EPA flaming trash creates 2,988 pounds of CO2 per megawatt hour. For the same power, coal makes 2,249 pounds of CO2 and natural gas makes 1,135 pounds. That doesn’t sound good until you consider that a lot of the CO2 released by burning trash is from stuff that was part of the earth’s carbon cycle. It’s carbon that was in the air not too long ago and would be returning there again, whereas the carbon released from burning fossil fuels was out of the carbon cycle for millions of years, sequestered away deep underground. So the EPA considers the CO2 impact of burning waste to be about a third as bad as it looks. But energy from garbage unequivocally cuts down on a much more insidious greenhouse gas: methane. Methane doesn’t stay in the atmosphere for hundreds of years like CO2 can, usually it’s out after a dozen. But this little molecule is so good at trapping heat, the EPA estimates one CH4 has 25 times the impact as one CO2 over the course of a century. And do you know what the third biggest source of man-made methane is in the United States? Landfills. Yep, 18% of the methane Americans make happens when we bury our trash and let microbes go to town on it. Methane is a key component of natural gas so some landfills capture it and sell it to power companies. You’d think the tradeoff would be reduced methane for increased CO2, but the number one source of methane emissions is natural gas and petroleum systems. You don’t get that methane when you burn junk, and as a bonus, you don’t have to burn as much natural gas or coal. Double win. Flaming heaps of trash isn’t as totally glamorous as I’m making it sound though. Like anything, it has it’s own foibles. It cuts down on greenhouse gasses but the tradeoff is it puts other pollutants into the air. Sulfur dioxide, which causes acid rain, is released, along with trace amounts of mercury compounds and dioxins which are highly toxic and build up in fatty tissue. Concerns over these chemicals are the main hindrance to adoption in the US, along with nobody wanting a trash burning facility in their backyard when there’s lots of cheap land. Sweden strictly regulates all these toxic byproducts, and even so plant representatives say their scrubbers reduce toxic chemical levels to half the legal limits. Some of these byproducts would still be present in landfills too, only then they’d have the potential to seep into groundwater if the landfills aren’t equipped with a protective lining. Environmentalists who oppose burning trash argue that the goal should be to reduce how much waste we make in the first place and recycle more, and they’re absolutely right. But there’s no evidence that burning waste will hurt recycling efforts. Sweden is expecting to step up recycling to from 50 to 60% in the coming years, and they’re only burning what they can’t use. Even though the US buries most of our trash, we only recycle 34% of it. So even though it’s not glamorous and not the cure-all for our refuse and energy woes, it looks like burning trash could actually be an important stopgap for climate change if it were more widespread. Egypt deals with its junk in a rather unusual and interesting way. Lisette and the team at our sister channel, Seeker, cover that right here. Where do you fall on the burning trash issue? For it? Hate it? Have some reservations about it after Toy Story 3? Let us know in the comments, subscribe if you haven’t already, and I’ll see you next time on DNews.
B2 中上級 米 なぜゴミを燃やさないのか? (Why Don't We Burn Our Trash?) 123 12 Jiangtao Wang に公開 2021 年 01 月 14 日 シェア シェア 保存 報告 動画の中の単語