Their initial idea was that garaged vehicles would have a two-way computer-controlled connection to the electric grid, which could receive power from the vehicle as well as provide power to it. It’s yet to be shown clearly why that’s good for the driver. The inverter converts alternating current to direct current when charging the vehicle and back the other way when sending power into the grid. It’s been 25 years since University of Delaware energy and environmental expert Willett Kempton and Green Mountain College energy economist Steve Letendre outlined what they saw as a “dawning interaction between electric-drive vehicles and the electric supply system.” This duo, alongside Timothy Lipman of the University of California, Berkeley, and Alec Brooks of AC Propulsion, laid the foundation for vehicle-to-grid power. So it’s a good moment to consider where vehicle-to-grid concepts first emerged and to see in Utrecht how far they’ve come. “We want to predict where we need to build the next electric charging station.” And part of the change involves extending the city’s EV-charging network. “We wanted to change,” says Eelco Eerenberg, one of Utrecht's deputy mayors and alderman for development, education, and public health. This initiative is taking place in an environment where everyday citizens want to travel without causing emissions and are increasingly aware of the value of renewables and energy security. Utrecht, a largely bicycle-propelled city of 350,000 just south of Amsterdam, has become a proving ground for the bidirectional-charging techniques that have the rapt interest of automakers, engineers, city managers, and power utilities the world over. To overcome the need for freshwater, there have been attempts to produce hydrogen from saline and brackish waters, but the devices have to deal with contamination and chlorine as a by-product. Solar-powered water-splitting devices, for example, use photocatalysts, which absorb sunlight to split water into hydrogen and oxygen but have a low solar-to-hydrogen efficiency of only 1 percent. Many teams are working on alternative ways to make green hydrogen. Green hydrogen from electrolysis is still a nascent technology because of the need for electrolyzers on a large scale. But most of the hydrogen around the world today is still produced from natural gas or coal. Hydrogen offers the prospect of clean, emission-free energy, and the hydrogen economy has gathered steam in the past few years due to increases in funding and improvements in technology. Li and his colleagues reported the details in the journal Nature Communications. Tests of the prototype direct-air electrolyzer over 12 consecutive days showed that it could produce almost 750 liters of hydrogen a day on average per square meter of electrolyzer. The success could open up the possibility of producing hydrogen in semi-arid regions, which also have some of the highest solar- and wind-power potential.

It is the first such electrolyzer to produce high purity (99 percent) hydrogen from air that has as little as 4 percent humidity, says Gang Kevin Li, a professor of chemical engineering at the University of Melbourne, in Australia.

Their electrolyzer extracts moisture from air and splits it via renewably powered electrolysis to create hydrogen.

Now, researchers have reported a way to make hydrogen fuel from just humidity in the air. The most sustainable way to make hydrogen fuel is to split water using renewable electricity-but that requires access to freshwater.

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