A technoeconomic analysis on solar hydrogen production was recently published in Energy. Environ. Sci. by Shaner, et al. (Energy. Environ. Sci., 2016, Advance Article). The levelized cost of hydrogen was compared between photovoltaic-electrolyzers (PV-E), photoelectrochemical cells (PECs), and fossil fuel derived hydrogen using steam methane reforming (SMR).
This paper highlights the strengths of PEC systems and outlines the challenges which must be met in order for the technology to become viable. One way to make solar hydrogen production competitive with SMR is to tax the carbon dioxide that is produced. They estimate that for the current PEC technology to achieve hydrogen price parity with SMR, a carbon tax of $1000/ton C02 is required. If a solar concentrator PEC is used, the estimated tax decreases to $800/ton CO2.
Check out this 3D printing pen. This could be quite useful for welding 3d printed parts together instead of using epoxy. It works with both PLA and ABS. Also, they sell an an educational bundle for outreach education — they share a bunch of class room curricula on their website.
Dr. Yiying Wu from Ohio State posted an AMA (Ask Me Anything) yesterday on Reddit’s science forum, where he answers questions about his work on solar batteries. This is a great way to increase public awareness of solar battery research, and is worth checking out if you have the time.
Here’s a neat chart that shows Germany’s resource usage for electricity production by date and hour. You can very clearly see the daily cycling of solar power generation. If you navigate to week 12 of 2015, you can see the dip in solar power generation during the March 20th solar eclipse!
Check out this new 3-D printing technique developed by Carbon3D, Inc. Current 3D printers form each layer individually with a point extruder from the bottom up. Carbon3D’s printer pulls its creations out of a liquid polymer bath, forming each layer from the top down! See it in action!
I want one.
The technique is called Continuous Liquid Interface Production (CLIP), and it allows for complex geometries to be printed at unprecedented speed. According to Carbon3D’s website, CLIP printing is 25 to 100 times faster than the current technology.
At these speeds, it also allows for much finer resolution. From the publication in Science, CLIP printing speed is limited by the resin cure rate and viscosity, not by stepwise layer formation. The printing resolution was reported to be as fine as 50 microns.
The CLIP process works by carefully controlling the rate of photon and oxygen delivery to the continually forming layers. At the bottom of the liquid polymer pool, there is a UV light image source and an oxygen permeable membrane. The UV light initiates polymerization, allowing the solid plastic to form. As the printer pulls the plastic out of the pool, the UV image changes continuously, like a movie, to create the shape of each forming layer. Oxygen is allowed to permeate through the membrane and compete with the UV polymerization. Oxygen keeps the polymer in the liquid phase at the boundary between the polymer and the permeable membrane. This allows new polymer to flow directly under the layers as they form and pull away.
You may have noticed CLIP’s resemblance to the liquid metal terminator from Terminator II: Judgement Day. According to The Washington Post, the idea for CLIP was inspired by the scene of the terminator’s self assembly from a pool of molten metal. There’s no need to fear though, CLIP printing can’t generate self-aware machines on a mission to destroy humanity. Yet.
Solaire Generation is an NYC based company that designs and installs solar structures. Pictured below is their solar carport design.For more information about the company, their website can be found here. Also, for Columbia’s Undergrads and Masters students, Solaire Generation will be at the All Ivy Environmental and Sustainable Development Career Fair on Friday, February 27th.
One way to increase the efficiency of a photovoltaic (PV) system is to selectively control which light wavelengths can reach the semiconductor. This is particularly useful for concentrated light designs (i.e. using mirrors and optics to direct more light to the PV cell), where longer wavelengths can generate enough heat to raise the panel temperature, reducing efficiency.
One method of controlling the incident wavelengths is to use tandem cells. These are cells with multiple semiconductor layers, each layer with a different bandgap capable of operating on a different region of the electromagnetic spectrum. Another method is to use optical filters to either reflect unwanted wavelengths or redirect them towards a solar-thermal device. More can be read about beam splitting here.
The University of New South Wales in Australia combined four different cells to create a photovoltaic system which achieved a system efficiency of 40.4% in concentrated sunlight. This level of efficiency is the highest value that’s been reported to date for sunlight conversion. The research for this project was conducted in a partnership with Raygen Resources, who’s website can be found here.
For more information about the company, their website can be found 
Esposito Research Group Blog 