How to Convert 100% Of CO2 Into Ethylene

A team of researchers led by Meenesh Singh at University of Illinois Chicago (UIC) has discovered a way to convert 100% of carbon dioxide captured from industrial exhaust into ethylene, a key building block for plastic products.  While researchers have been exploring the possibility of converting carbon dioxide to ethylene for more than a decade, the UIC team’s approach is the first to achieve nearly 100% utilization of carbon dioxide to produce hydrocarbons. Their system uses electrolysis to transform captured carbon dioxide gas into high purity ethylene, with other carbon-based fuels and oxygen as byproducts.  

The process can convert up to 6 metric tons of carbon dioxide into 1 metric ton of ethylene, recycling almost all carbon dioxide captured. Because the system runs on electricity, the use of renewable energy can make the process carbon negative.  According to Singh, his team’s approach surpasses the net-zero carbon goal of other carbon capture and conversion technologies by actually reducing the total carbon dioxide output from industry.

It’s a net negative,” he said. “For every 1 ton of ethylene produced, you’re taking 6 tons of CO2 from point sources that otherwise would be released to the atmosphere.” 

Previous attempts at converting carbon dioxide into ethylene have relied on reactors that produce ethylene within the source carbon dioxide emission stream. In these cases, as little as 10% of COemissions typically converts to ethylene. The ethylene must later be separated from the carbon dioxide in an energy-intensive process often involving fossil fuels.   In UIC’s approach, an electric current is passed through a cell, half of which is filled with captured carbon dioxide, the other half with a water-based solution. An electrified catalyst draws charged hydrogen atoms from the water molecules into the other half of the unit separated by a membrane, where they combine with charged carbon atoms from the carbon dioxide molecules to form ethylene. 

Among manufactured chemicals worldwide, ethylene ranks third for carbon emissions after ammonia and cement. Ethylene is used not only to create plastic products for the packaging, agricultural and automotive industries, but also to produce chemicals used in antifreeze, medical sterilizers and vinyl siding for houses. Ethylene is usually made in a process called steam cracking that requires enormous amounts of heat. Cracking generates about 1.5 metric tons of carbon emissions per ton of ethylene created. On average, manufacturers produce around 160 million tons of ethylene each year, which results in more than 260 million tons of carbon dioxide emissions worldwide

In addition to ethylene, the UIC scientists were able to produce other carbon-rich products useful to industry with their electrolysis approach. They also achieved a very high solar energy conversion efficiency, converting 10% of energy from the solar panels directly to carbon product output. This is well above the state-of-the-art standard of 2%. For all the ethylene they produced, the solar energy conversion efficiency was around 4%, approximately the same rate as photosynthesis.
Their findings are published in Cell Reports Physical Science.


Electric Aircraft Powered By Hydrogen Fuel Cells

Developers unveiled a hover craft billed as the first flying vehicle to be powered by hydrogen fuel cells on Wednesday in Southern California, in a show-and-tell that raised some eyebrows but never left the ground.  Massachusetts aerospace company Alaka’i Technologies has thrown its hat into the urban air mobility ring, announcing development of an electric vertical take-off and landing (eVTOL) aircraft powered by hydrogen fuel cells.

The power system differentiates the company’s conceptual five-passenger aircraft, called Skai, from other high-profile battery– and hybrid-powered designs unveiled in recent months. Alaka’i‘s concept is unique because many concepts for eVTOL aircraft would be fully or partially powered by lithium ion batteries, a market-proven but imperfect battery chemistry.

Designed by Alaka’i in partnership with BMW Group’s Designworks division, Skai will eventually be capable of carrying up to five passengers and performing missions such as disaster recovery and medical flights, says Alaka’i, which takes its name from the Hawaiian word for “leader“.


We are moving swiftly and have developed applications for immediate testing and use this year. Our best estimate is Skai will be in practical use in the year 2021,” says Alaka’i co-founder and chief technology officer Brian Morrison.

Skai likely will first perform non-passenger missions, with full certification from the US Federal Aviation Administration to follow, he says. Skai will initially have one pilot and carry four passengers, but the company envisions the design evolving to a fully autonomous, five-passenger aircraft.

Skai will have 400nm (741km) range, ability to carry payloads of 1,000lb (454kg), flight duration of 4h and be capable of about 100kt (185km/h) speeds. Alaka’i expects an eventual Federal Aviation Administration variant of Skai will have capacity to carry five passengers. The conceptual aircraft’s three fuel cells will generate electricity needed to power six motors, each of which will drive a single lifting prop. The company calls the hydrogen fuel system safe and environmentally friendly. The aircraft’s systems will generate hydrogen by stripped it from water in a process called electrolysis.

Fuel cells use an electrochemical reaction to break hydrogen molecules into protons and electrons. The electronics travel through a circuit, creating electricity, then reunite with the protons and with oxygen to create water and heat, according to the US Department of Energy. Morrison declines to specify the state of Alaka’i’s fuel cell technology, calling that information proprietary.

Skai will carry 200 litres (53 USgal) or 400 litres of “liquid hydrogen” in onboard tanks, and refueling will take less than 10min, it says. The fuel cells will have lifespans of 15,000-20,000h of flight, says Alaka’i.