There are countries in the developing world lacking infrastructure to provide their rural citizens with basic electrical energy.
Intrigued by this problem, researchers in one sector of the scientific community have, with insightful ingenuity, come up with a possible solution in a form described as an “artificial leaf.”
Inspired by nature, the device developed by Dr. Daniel G. Nocera and his team uses a thin wafer of semi-conducting silicon, about the size of a credit card, covered in catalysts made from relatively cheap materials.
His first artificial leaf was developed in 2011 while he was still at MIT. Now at Harvard, his team has made further improvements to the original “artificial leaf” design.
The leaf is designed to produce energy from sunlight and water by using a simple catalyst reaction and a semi-conducting solar cell to produce hydrogen and oxygen.
Dropped in a jar of water, the thin sheet with cobalt-based catalyst bonded to one side and a nickel — molybdenum — zinc catalyst to the other, produce hydrogen and oxygen from opposite sides of the small device.
When placed in a container with a divider to keep the two elements separate, each can then be collected as they bubble to the surface. A fuel cell is required to use the hydrogen and oxygen to generate electricity.
With the first prototype, their results were very encouraging. With the mechanism in a quart of water, it developed 100 watts of electric power from the resulting gases in quantities large enough to provide electricity for 24 hours.
However, if unpurified water was used, the ever-present bacteria found in natural water sources would form a biofilm, smothering the leaf’s ability to produce hydrogen.
Now, new developments in catalysts and application methods allows miniscule pieces of the cobalt-based surface coating to flake off, creating an irregular surface upon which the bacteria cannot form a biofilm.
The catalyst then has the ability to “self-heal and re-assemble” itself, and it is this constant reforming that keeps the process operating.
However, as with all new technologies some shortfalls are evident. The system conversion to fuel is 70 to 80 per cent efficient but the silicon cell has an overall efficiency of only five per cent.
Compared to a basic silicon solar cells’ efficiency of about 10 per cent, it is encouraging further research.
The energy-generating artificial leaf system has a distinct advantage over regular photovoltaic cells as the hydrogen/oxygen supply powers the fuel cell during the night and throughout cloudy periods.
Fuel cells are a necessary component to complete the system, and although they have been around for a long time, they are still fairly high priced and not in common usage around the world.
Not everyone has the funds of a major corporation or NASA. However, Panasonic and other companies around the world are working on fuel cell systems with the intent of making them more affordable.
Overcome the technical difficulties, and natural water, found almost everywhere, may someday be a common source of fuel.
Lorne Oja is an energy consultant, power engineer and a partner in a company that installs solar panels, wind turbines and energy control products in Central Alberta. He built his first off-grid home in 2003. His column appears every second Friday in the Advocate. Contact him at: email@example.com.