Current climate targets require negative carbon dioxide (CO₂) emissions. Direct air capture is a promising negative emission technology, but energy and material demands lead to trade-offs with indirect emissions and other environmental impacts. Here, we show by life-cycle assessment that the commercial direct air capture plants in Hinwil and Hellisheiði operated by Climeworks can already achieve negative emissions today, with carbon capture efficiencies of 85.4% and 93.1%. The climate benefits of direct air capture, however, depend strongly on the energy source. When using low-carbon energy, as in Hellisheiði, adsorbent choice and plant construction become more important, inducing up to 45 and 15 gCO₂e per kilogram CO₂ captured, respectively. Large-scale deployment of direct air capture for 1% of the global annual CO₂ emissions would not be limited by material and energy availability. However, the current small-scale production of amines for the adsorbent would need to be scaled up by more than an order of magnitude. Other environmental impacts would increase by less than 0.057% when using wind power and by up to 0.30% for the global electricity mix forecasted for 2050. Energy source and efficiency are essential for direct air capture to enable both negative emissions and low-carbon fuels.

当前的气候目标要求负二氧化碳 (CO ₂ ) 排放。直接空气捕获是一种很有前途的负排放技术，但能源和材料需求导致与间接排放和其他环境影响的权衡。在这里，我们通过生命周期评估表明，由 Climeworks 运营的位于 Hinwil 和 Hellisheiði 的商业直接空气捕集厂如今已经可以实现负排放，碳捕集效率分别为 85.4% 和 93.1%。然而，直接空气捕获的气候效益很大程度上取决于能源。当使用低碳能源时，如在 Hellisheiði，吸附剂的选择和工厂建设变得更加重要，每公斤 CO _{2 可产生}高达 45 和 15 gCO ₂ e分别捕获。_{为全球每年 CO 2}排放量的 1% 大规模部署直接空气捕获将不受材料和能源可用性的限制。然而，目前用于吸附剂的胺的小规模生产需要扩大一个数量级以上。使用风能时，其他环境影响将增加不到 0.057%，而对 2050 年全球电力结构的预测则增加 0.30%。能源和效率对于直接空气捕获以实现负排放和低碳燃料至关重要。