ok, back up.

the first thing you may be thinking is: since when does leonardo dicaprio have anything to do with climate change or the united nations? he’s usually too busy freezing to death off the titanic or messing around with quaaludes as a “wolf of wall street.” but dicaprio has been involved with environmental issues since back in the day when there actually was a clinton in office. 

anyways, dicaprio spent two years traveling the world to film his documentary on climate change called, “before the flood.” the culminating end will have you on the edge of your seat in an apocalyptic finale, which is all indisputably and unfortunately backed up with real science. (watch the trailer here: https://youtu.be/6ugsrcxasai)

but let’s get back to what we were talking about. what the heck is a gigafactory? and how is it going to save the world?

in 2014, construction of the tesla gigafactory began in reno, nevada, with the mission of generating greater outputs of lithium ion batteries to keep up with the increasing demand of electric cars in the global market. by 2018, the gigafactory will be working at full capacity, and “will be powered by renewable energy sources, with the goal of achieving net zero energy,” according to the tesla website. it will create more lithium ion batteries than were made worldwide in 2013, and musk said, “it will actually be bigger than the sum of all lithium ion factories in the world.” the planned battery production capacity will be 35 gigawatt-hours (gwh) per year.

here we have some riveting energy math:

1 gwh = 1 million kwh = 1 billion watts for one hour

think of the good we could do with 35 gigawatt-hours of clean energy. the reduction in carbon emissions and other pollutants from our current reliance on fossil fuels will be a pretty big deal, to say the least.

now imagine a world with 100 gigafactories and 3500 gigawatt-hours ruling the planet. this is where we need to get to, but we can’t just tell our pal elon to finish saving the world for us. “tesla can’t build 100 gigafactories. the thing that is really going to make a difference is if companies that are much bigger than tesla do the same thing,” musk said.

so this is where we are right now. we need 100 gigafactories. we need the major global corporations with the biggest environmental impacts to make real investments in their sustainable futures, aka our futures. most importantly, we need to get this done before there are no more icebergs left for the titanic to crash leo into, because he does a damn good job at dying for the love of his life.

—

learn more: 

• https://www.tesla.com/gigafactory
• http://channel.nationalgeographic.com/before-the-flood/

the surface area of this porous silicon is high,” said donghai wang an assistant professor of mechanical engineering at penn state. “it is widely used and has a lot of applications.”

the standard method for manufacturing porous silicon is a subtraction method, similar to making a sculpture.

“silicon is an important material because it is a semiconductor,” said wang. “typically, porous silicon is produced by etching, a process in which lots of material is lost.”

wang’s team uses a chemically based method that builds up the material rather than removing it. the researchers start with silicon tetrachloride, a very inexpensive source of silicon. they then treat the material with asodium potassium alloy.

“the bonds between silicon and chlorine in silicon tetrachloride are very strong and require a highly reducing agent,” said wang. “sodium potassium alloy is such an agent.”

once the bonds break, the chlorine binds with the sodium, potassium and silicon, potassium chloride and sodium chloride — table salt — become solid, forming a material composed of crystals of salt embedded in silicon. the material is then heat-treated and washed in water to dissolve the salt, leaving pores that range from 5 to 15 nanometers. the researchers report their results in today’s (apr. 10) issue of nature communications.

because sodium potassium alloy is highly reactive, the entire procedure must be done away from the oxygen in the air, so the researchers carry out their reaction in an argon atmosphere.

“i believe that the process can be scaled up to manufacturing size,” said wang. “there are some processes that use sodium potassium alloy at industrial levels. so we can adapt their approaches to make this new type of porositic silicon.”

because these silicon particles have lots of pores, they have a large surface area, and act as an effective catalyst when sunlight shines on this porous silicon and water. the energy in sunlight can excite an electron that then reduces water, generating hydrogen gas. this process is aided by the material’s larger-than-normal band gap, which comes from the nanoscale size of the silicon crystallites.

“this porous silicon can generate a good amount of hydrogen just from sunlight,” said wang.

the researchers are also looking into using this porous silicon as the anode in a lithium ion battery.

other researchers on this project were fang dai, jiantao zai and hiesang sohn, all postdoctural researchers in mechanical engineering; and ran yi, mikhail l gordin and shuru chen, graduate students in mechanical engineering.

the u.s. department of energy and the defense threat reduction agency funded this work.