University of California nano-engineers have developed a new type of nano-scale motor that could be used in future bio-engineering endeavours to directly pump excess CO2 out of the ocean, thus aiding in the global effort to curb greenhouse gas emissions.
“This system is a promising approach to rapid and enhanced CO2 sequestration [the capture and long-term storage of environmental carbon dioxide] platforms for addressing growing concerns over the build-up of greenhouse gas,” state the authors of a recent study, describing the promising new technology.
These nano-motors would self-propel by using environmental enzymes and convert the noxious substance into a solid as they go.
“In the future, we could potentially use these micro-motors as part of a water treatment system, like a water decarbonation plant,” said study co-author Kevin Kaufmann.
Using water flow and carbonic anhydrase (CA), employed as a catalyst, these tiny proof-of-concept devices would rapidly convert carbon dioxide into calcium carbonate (a compound found in shells and coral), which is currently one of the most environmentally-reliable methods of reducing CO2 mass in water.
A series of specially designed experiments showed these little robotic helpers to be capable of removing up to 90 percent of carbon dioxide from ionised water solutions that contain CO2 within five minutes. The same result was achieved with seawater, the only difference being a 2 percent lower clearance rate.
According to the research team, most of the CO2 sequestration scenarios currently discussed in governmental and business circles are hardly something to be overly enthusiastic about. Each of these “has its own disadvantages, such as high cost, high energy input, use of harsh chemicals, and [the] generation of pollutants”.
Instead of relying on these, scientists could deploy the new, autonomous micro-motors that use the environment itself to move around and cost much less to produce.
One of the barriers to overcome before these devices are released out “into the world”, however, is related to their self-propelling mechanism – currently, they use hydrogen peroxide, which reacts with platinum in their casing to create oxygen, allowing them to move. Pending further research, it is not known whether this could be applied on a massive scale.
On the up side, the motors are impressively fast. Water infused with just two to four percent hydrogen peroxide allows them to reach a speed of up to 100 micrometres per second – quite a considerable feat for bots of this size.
The next step in development will be to re-design the motors to run on other minerals that are not as expensive as hydrogen peroxide and more abundant in the intended environment.
“If the micromotors can use the environment as fuel, they will be more scalable, environmentally friendly and less expensive,” said Kaufmann.