Kreg Kaminski & Thomas Larson​

Personal Energy: Using Excess Solar Power to Split Water and Store Hydrogen



Solar Power
Currently when solar panels are placed on a house the power it generates is used to power the electronics and light in the home. When the panel is producing more power than is being used then the excess is stored in a battery. When power consumption is greater than the power produced by the solar panel like at night or on a clousy day, then the energy from the battery is used until all available energy is used and power from the grid has to run the home's electronics.
This is the standard model for running a home on solar power. Research starting in 2008 a man named Dan Nocera at MIT's energy department has shifted this model to a more efficient way to store the excess energy of solar power. Not in an inefficient battery, but as hydrogen gas.

The main problem with solar panels is storing the energy. Batteries do not have the energy desity to effectivly store power for later use. They are too expensive and heavy. Below is a slide taken from one of Dan Nocera's talks where he points out that with the current methods of storing solar energy are not efficient enough to be practical in homes and developing nations. His research at MIT has greatly reduced the energy needed to turn water into hydrogen and oxygen gas. Hydrogen has the highest energy density by weight and if it could be used as the main source of energy storage from solar, wind, and water in the future then the energy (and water) needs of the entire world can be met.
This is a link to MIT NEWS, there is a two minute video interview with Nocera that I cannot embed on the wiki.
When the process was first implimented in 2008 the catalysts used were cobalt, phosphate and an electrode to produce O2 and a platinum catalyst to produce H2. Since 2008 both catalytic reactions have been replaced with cheaper materials.

New Catalysts
Recently the cobalt-phosphate electrode has been replaced with nickel borate, this is a much cheaper materal than cobalt.
The platinum that is used to obtain hydrogen from water is also used in hydrogen fuel cells, this accounts for 1/3 of the cost for the cells. Nocera has yet to unveil his new replacement for platinum, but since 2008 his methods have yeilded one hundred times more hydrogen since the start of his research. One new replacement is nickle placed in the enzyme hydrogenase, this is only for recombining the H2 and the O2 back into water but the principal is that new catalysts are constantly being discovered. In an article from MIT Nocera points out that there is room for improvment with the catalysts he uses,they have yet to find the "silver bullet" but he claims that this will happen soon in the coming years.

Nocera's proposed system

This would be a normal American Home. The energy not used to power the home would electrolyze water into hydrogen and oxygen, then at night those gasses can run a fuel cell and provide electricity. The electrolyzer and the storage of gasses is the easy part, building cheaper solar cells and fuel cells is still relativly far off. Although both are becoming more efficient every year.

Fuel Cells

Fuel cells work by pumping hydrogen along a anode with the platinum catalyst(which is getting more effecient and replaced with cheaper materials) the electrons are stripped from the H2. Each hydrogen gas particle losses two electrons that run along a wire that is the power of the cell, and two protons that move though the platinum and an electrolite to the other side of the wafer where it is combined with oxygen gas to form water.




Hydrogen Storage is the easiest problem faced by this system. Its is as easy and safe as propane and could be stored under relativly warm conditions.
In the future this storage of energy as chemical bonds can be used to create liquid fuels instead of hydrogen. Also currently the gas does not need to be used in fuel cells, it can be used to run internal combustion engines that have been massed produced since 2007. Below is a BMW engine that has been in production in Europe.

bmw-hydrogen-engine.jpg The future of energy cannot be fossil fuels, there are not enough and they should not be used by developing nations. If this becomes a reality then the indivudual can greatly benefit. With the catalysts being used the water needed does not need to be basic like in industrial electrolyzers used today. In his talk at the bottom of the page Nocera says that his catalysts outlast industrial equivalents and they use water out of the Charles at MIT. Waste water, salt water, or water from a stream can be used in third world countries to convert to hydrogen, then when the fuel cell is used to generate power it also gives off waste as clean drinking water. This is energy and water purification in one small system that can be created from PVC piping and a solar cell or wind turbine. The current setup costs $100 as of a year and a half ago (I could not find anything more recent).

Dan Nocera's Talk on Personalized Energy

This is Nocera's talk to a recearch group in 2009. He calculated the energy needs for the next forty years and the potential solutions to cope with the increased consumption. Water has the greatest potential to meet the energy needs of future. The energy problem and the water problem are addressed together as power plants waste massive amounts of water to create electricity. With an olympic sized swimming pool turned into hydrogen a second the energy needs of the entire world can be achieved, and with his newly founded company that works to make his system cheaper he is working towards suplying energy to every person globaly. Sun Catalynix has recieved funding from DARPA and a ten million dollar grant from MIT to continue his research.

Works Cited

  • Pop Tech
  • Wimp
  • Wikipedia