New device captures carbon dioxide by pumping it across a battery

新型装置通过电池泵送捕获二氧化碳

Equipment to capture carbon dioxide from ambient air or smokestacks generally works through a sort of reversible filter. Air is passed through granules or a liquid that absorbs the CO2, then that CO2-loaded substance undergoes a process (usually heating) that causes it to let go of all that CO2. The resulting gas can be collected in a separated stream. 用于从环境空气或烟囱中捕获二氧化碳的设备通常通过一种可逆过滤器来工作。空气通过吸收二氧化碳的颗粒或液体，然后这种负载了二氧化碳的物质会经历一个过程（通常是加热），使其释放出所有的二氧化碳。由此产生的气体可以被收集在分离的流中。

It’s also possible to do a similar sort of operation on a smaller scale—like inside a battery. A new study from a team led by James Buchen of the University of Delaware demonstrates an example of a battery-based electrochemical carbon-capture technique that they say is more viable than previous attempts. It has the potential to require less energy—and therefore be cheaper—than the reversible-filter designs that currently dominate. 在较小的规模上进行类似的操作也是可能的——比如在电池内部。特拉华大学 James Buchen 领导的团队进行的一项新研究展示了一种基于电池的电化学碳捕获技术，他们称该技术比之前的尝试更具可行性。与目前占主导地位的可逆过滤器设计相比，它有可能需要更少的能量，因此成本更低。

Carbon chemistry

碳化学

The basic idea behind a device of this type is that hydroxide produced at the battery cathode reacts with CO2, converting it to carbonate or bicarbonate that passes through the separator membrane to the anode. There, the lower pH causes the reaction to reverse, with carbonate turning back into CO2 gas. The role of the cathode is to produce hydroxide ions; the role of the anode is to consume them. 这种装置背后的基本原理是：电池阴极产生的氢氧根离子与二氧化碳反应，将其转化为碳酸盐或碳酸氢盐，并通过隔膜传输到阳极。在那里，较低的 pH 值使反应逆转，碳酸盐重新变回二氧化碳气体。阴极的作用是产生氢氧根离子，而阳极的作用是消耗它们。

In this case, both the cathode and anode are nickel hydroxide. That’s the same as the cathode in the old-school rechargeable AA and AAA nickel-metal hydride batteries. But instead of a battery you can charge full of energy to power some mobile device, this works more like a chemical seesaw. Apply a voltage in one direction and you drive the cathode to make hydroxide that moves to the anode. Switch the applied voltage around, and the old anode becomes the new cathode, driving the exact same chemistry in reverse. And the whole time this device is grabbing CO2 and transporting it across the cell. 在这种情况下，阴极和阳极都是氢氧化镍。这与老式可充电 AA 和 AAA 镍氢电池中的阴极相同。但它不是那种可以充满电来为移动设备供电的电池，它的工作方式更像是一个化学跷跷板。向一个方向施加电压，就会驱动阴极产生氢氧根离子并移动到阳极。反转施加的电压，旧的阳极就变成了新的阴极，驱动完全相同的化学反应逆向进行。在此过程中，该装置一直在捕获二氧化碳并将其输送穿过电池。

The researchers tested a lab-scale device made of nine cells stacked together, each with an area of about half a letter-sized sheet of paper. A blower pushed air through sinuous air channels in the plates sandwiching each cell together (using components borrowed from fuel cells). This small device used electricity at a rate of about 0.8 megawatt-hours per ton of captured CO2. Current facilities capturing carbon from ambient air are in the neighborhood of 1.5 to 3 megawatt-hours per ton of CO2. 研究人员测试了一种由九个电池堆叠而成的实验室规模装置，每个电池的面积约为半张信纸大小。鼓风机将空气推入夹在每个电池之间的板上的蜿蜒空气通道中（使用了从燃料电池中借用的组件）。这种小型装置捕获每吨二氧化碳的耗电量约为 0.8 兆瓦时。目前从环境空气中捕获碳的设施，每吨二氧化碳的耗电量在 1.5 到 3 兆瓦时左右。

Piloting the process

试点该工艺

Several of the researchers on the team are part of a startup called RepAir Carbon that is based on this technology, and part of the paper is spent on sketching out financial feasibility at scale. Estimating the cost for an initial small pilot plant (about $566 per ton of captured CO2), they use the learning rate from the lithium-ion battery industry and some common cost scaling for bigger plants to project forward a couple of pilot generations. 该团队的几位研究人员参与了一家名为 RepAir Carbon 的初创公司，该公司正是基于这项技术。论文的一部分专门用于勾勒大规模应用的财务可行性。在估算最初小型试点工厂的成本（每捕获一吨二氧化碳约 566 美元）时，他们利用锂离子电池行业的学习率和一些大型工厂的常见成本缩放比例，对未来几代试点项目进行了预测。

For a plant with a thousand times the capacity of their pilot, they estimate they could get to $92 per ton of captured CO2. That would be much cheaper than has so far been achieved by companies like Climeworks, which is aiming to get down to $250–$350 per ton by 2030—and has demonstrated how difficult it can be to meet optimistic scaling projections. Targeting $100 per ton has long been the goal in the carbon-capture world, as costs that low could spur much wider adoption. Adding to the number of technologies being pursued may improve the odds that one of them reaches that goal. 对于一个产能是其试点项目一千倍的工厂，他们估计可以将成本降至每吨二氧化碳 92 美元。这将比 Climeworks 等公司迄今为止实现的成本要便宜得多，后者目标是在 2030 年前将成本降至每吨 250-350 美元，这也证明了实现乐观的规模化预测是多么困难。每吨 100 美元一直是碳捕获领域的目标，因为如此低的成本可以促进更广泛的采用。增加正在研发的技术数量，可能会提高其中某项技术实现该目标的几率。