两个月前, 《双语周刊》曾刊登过一篇关于二氧化碳捕捉与存储的文章。现在，科学家们又提出一个大胆的设想：利用人造树吸附空气里的二氧化碳，其吸附能力是真树的一千倍。

    By Ji Yongyong

    Carbon capture and storage (CCS) is an emerging tool designed to curb carbon dioxide emissions. However, its drawback is that the capture process is energy intensive. For countries like China that are experiencing rapid growth in electricity demand, CCS may  be a hard sell. 

    Columbia University geophysicist Klaus Lackner is challenging conventional CCS designs with a radical concept -- “synthetic trees” that capture carbon dioxide from the air. Mr. Lackner debuted his concept at a recent  event.

    The synthetic trees are actually high-tech towers containing special absorbents that scrub carbon dioxide from moving air and then hold the gas until it can be processed and stored. Currently, the technology is not cheap, but Mr. Lackner said the first synthetic trees could be in operation in two years. He conceded that there is still a long road    ahead before synthetic trees can be fully commercialized.

    The captured carbon dioxide could be sold to the industrial or beverage industries, enhancing the economic viability of this technology. If the technology is widely deployed, economies of scale would diminish the cost per unit for synthetic trees. 

    When a skeptical audience member suggested simply planting real trees,   Mr. Lackner responded that real trees capture less carbon dioxide. He estimated that synthetic trees could be 1,000 times more efficient in pulling carbon dioxide from the air. Approximately a million synthetic trees would be needed globally to lower carbon dioxide levels to an acceptable level, asserted Mr. Lackner, if each tree absorbed a ton of carbon dioxide per day.

    Another advantage over the conventional carbon capture methods is that synthetic trees can be built onsite, said Mr. Lacker. The resultant carbon dioxide would not have to be transported offsite for reuse.