The work of Yi Cui, Associate Professor of Materials Science and Engineering at Stanford University, has garnered a great deal of interest, especially with his paper "High Performance Silicon Nanowire Field Effect Transistors" that has become the second most cited paper in the ACS journal Nano Letters over the past 10 years.

A few years back, I noted his work in replacing the lithium in the anodes of li-ion batteries with silicon nanowires and thereby increasing the battery life of a laptop to over 20 hours.

Now Cui and his colleagues have developed a material that improves on the technique of generating electricity by exploiting the difference in salinity between freshwater and saltwater.

The technique of using the combination of fresh and saltwater to generate electricity has become known as pressure-retarded osmosis and is being used in a working prototyple plant in Norway run by Statkraft

While Statkraft has claimed a goal of converting 80 percent of the available chemical energy this technique to electricity, Cui is quoted as believing that the best efficiency they can really hope for is 40 percent.

The material that Cui has developed is a manganese-dioxide nanorod that makes up the electrode, and, according to Cui, because this material offers 100 times more surface area for the sodium ions to interact with and allows those ions to attach and detach more quickly from the electrode.

The result is that Cui’s team was able to convert 74 percent of the potential energy that exists between the fresh and salt water into electricity, and, if the electrodes are brought closer together, could possibly achieve 85 percent efficiency.

Cui offers some pretty stunning calculations on how much energy could be produced if “all of the freshwater from all of the world's coastal rivers were harnessed.” He calculates that roughly 2 terawatts of electricity would be produced under such circumstances, or 13 percent of the world’s current energy demand.

Needless to say, nobody is going to undertake such a project on that scale since not only would it disturb sensitive aquatic habitats but also it would likely have large energy costs as well. 

But an outfit like Statkraft might take an interest in the new material to see if it will bump some salinity power technology over the 80 percent efficiency mark.

The Conversation (0)

3D-Stacked CMOS Takes Moore’s Law to New Heights

When transistors can’t get any smaller, the only direction is up

10 min read
An image of stacked squares with yellow flat bars through them.
Emily Cooper
Green

Perhaps the most far-reaching technological achievement over the last 50 years has been the steady march toward ever smaller transistors, fitting them more tightly together, and reducing their power consumption. And yet, ever since the two of us started our careers at Intel more than 20 years ago, we’ve been hearing the alarms that the descent into the infinitesimal was about to end. Yet year after year, brilliant new innovations continue to propel the semiconductor industry further.

Along this journey, we engineers had to change the transistor’s architecture as we continued to scale down area and power consumption while boosting performance. The “planar” transistor designs that took us through the last half of the 20th century gave way to 3D fin-shaped devices by the first half of the 2010s. Now, these too have an end date in sight, with a new gate-all-around (GAA) structure rolling into production soon. But we have to look even further ahead because our ability to scale down even this new transistor architecture, which we call RibbonFET, has its limits.

Keep Reading ↓Show less
{"imageShortcodeIds":[]}