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[ti:What Is ‘Direct Air Capture’, Can It Help Fight Climate Change?]
[by:www.21voa.com]
[00:00.00]快捷键：S播放/暂停，A快退，D快进，W循环。
[00:01.24]Governments and industries increasingly are exploring
[00:07.32]ways to remove carbon dioxide (CO2) from the atmosphere.
[00:15.08]CO2 is a major polluter.
[00:18.72]The waste gas traps heat in the atmosphere,
[00:22.80]causing the planet to warm.
[00:26.56]The United States launched a $3.5 billion program last year
[00:34.36]aimed at the permanent storage of CO2
[00:39.36]using a process known as Direct Air Capture (DAC).
[00:47.72]DAC technology uses chemical reactions
[00:53.16]to remove carbon dioxide from the air.
[00:58.24]The CO2 can then be stored underground
[01:02.92]or used in making products such as concrete or aviation fuel.
[01:10.92]The world's largest operating DAC plant,
[01:15.24]Climeworks' Orca plant in Iceland,
[01:18.84]can remove about 3,600 metric tons of CO2 each year.
[01:27.92]The CO2 is then stored deep underground.
[01:33.44]The US program hopes to build much larger plants
[01:38.48]that could store almost one million metric tons each year.
[01:44.92]Natural ways to remove carbon,
[01:47.60]such as planting trees and forest management,
[01:52.60]cost far less than DAC, currently.
[01:58.20]Data from The World Resources Institute,
[02:02.40]an environmental and research organization,
[02:06.84]say these natural methods
[02:09.52]cost close to $50 per metric ton of carbon,
[02:15.08]while DAC currently costs closer to $1,000 per metric ton.
[02:24.64]There are still other ways to deal with CO2, like BECCS.
[02:31.00]The bioenergy with carbon capture and storage process
[02:37.16]uses the electricity produced by burning biomass
[02:42.20]such as small wood pieces.
[02:45.72]The CO2 is captured and stored during its release.
[02:51.20]Biochar is a form of charcoal
[02:55.32]produced when organic matter such as leaves and wood
[03:01.12]is heated at high temperatures without oxygen.
[03:05.20]This produces a carbon rich substance
[03:09.84]that can be used as fertilizer.
[03:13.12]Techniques are also being developed
[03:16.68]to remove CO2 from seawater.
[03:21.16]Carbon capture and storage (CCS)
[03:25.36]is another technology to deal with CO2.
[03:31.00]CCS is traditionally deployed at industrial smokestacks
[03:37.28]such as fossil fuel power factories.
[03:41.16]It captures the CO2 and stores it
[03:45.32]before it reaches the atmosphere.
[03:48.60]CCS is considered carbon removal
[03:52.64]only if it stores more carbon than the site releases.
[03:59.44]Carbon removal methods such as DAC
[04:03.92]may be very useful if they can pull pollution from the air
[04:09.96]and store it permanently in the Earth or in new products.
[04:16.44]Some environmental groups worry
[04:19.32]that companies will use technical solutions like DAC
[04:25.00]as an excuse not to reduce their CO2 releases.
[04:32.08]The groups also link the issue to environmental justice
[04:36.92]as heavy polluting sites are often in,
[04:41.68]or near, poor and minority communities.
[04:47.64]I'm Andrew Smith.