64 years ago this week, the Hoover Dam opened to become the world’s largest hydroelectric dam. Originally called Boulder Dam, the project was named in honor of President Herbert Hoover ’95 (allegedly the first Stanford student ever), who helped design the project while he was still the Secretary of Commerce. Unlike the economy during the Hoover Administration, the water in the dam was intended to go downhill, through turbines, supplying power and water to California and Nevada. While there were some environmental consequences from the dam, the abundant clean energy it provided has more than made up for its impact. The Dam provides the same amount of power (4 TWhr) every year as 100 million gallons of gas. Despite an otherwise rocky career, and with all due respect to our overlords in his tower, the Hoover Dam is probably Hoover’s best contribution to society.

Developing clean sources of energy will be a key challenge for the scientific community over the coming decades. Even for the few holdouts that are not convinced of the potential time bomb of anthropogenic climate change, there are a multitude of boons that affordable, renewable energy provides. Providing a means for anybody to generate energy sustainably will help reduce global poverty and ease international tensions. While there are many technologies being explored, I would like to talk about some of the latest advances in solar technology that could potentially be even more monumental than the Hoover Dam.

In a nutshell, solar energy can be harnessed by capturing photons from sunlight, and converting their energy into electrical energy in a process called the photovoltaic effect. The most common materials used to capture photons are semiconductors. Incident photons on these materials induce an electric current which then travels through power lines to power your laptop. Currently, the best solar cells in the world can convert only around 43 percent of sunlight into electrical energy, so there is significant room for improvement.

Two weeks ago, researchers at Caltech announced that they successfully synthesized flexible solar cells that are much cheaper than conventional cells. Rather than being composed of sheets of semiconductor wafers, the new cells are made up of a polymer with millions of nanowires made out of silicon inside (picture raw spaghetti frozen in jello). This affords the cells flexibility, and also makes them much cheaper to produce – silicon is among the most expensive elements of a cell, and these cells require only about two percent of the typical amount. As an added benefit, by varying the makeup of the wires, the researchers were able to make them tremendously efficient, surpassing what was thought to be the theoretical light-trapping limit, and absorbing 96 percent of incident sunlight at the most efficient wavelength, as well as capturing sunlight across the spectrum. This technology is currently being scaled up and could be employed commercially within a couple of years.

In contrast to pushing modern technology to its limit, researchers at Oregon State have turned to more atavistic solutions to achieve similar effects by employing diatoms, tiny unicellular algae that have remained fairly constant for the last 100 million years. They are generally coated with a protective crystalline layer of silica. Gregory Rorrer and his team at Oregon State removed the diatoms from their shells and replaced the inside of the shells with titanium oxide (People for the Ethical Treatment of Diatoms should be calling any minute). By inserting these shells into a dye, the team developed an affordable and efficient way of harvesting solar energy using tools that have been around for millions of years.

Another example comes from Broadband Solar, a Bay Area Startup founded by Stanford materials science and engineering Prof. Mark Brongersma, which has recently developed a clever coating made up of amorphous silicon that can increase the efficiency of thin-film solar cells by up to 50 percent. Amorphous silicon is cheap and abundant, and when applied to the surface of a solar cell, can help direct photons onto the cell and trap them there, resulting in the formation of a surface Plasmon – essentially a strong interaction between the photon and the material that can induce a strong current. While most of the work has been modeled through computer simulations, Broadband is looking to develop these technologies in the coming years.

Stanford is at the epicenter in both time and space of the quest to provide clean, affordable, renewable energy to the planet. While every option should be explored, solar technology has vast potential for improvement, and Stanford has a long history of innovation in the field of solar research. The Stanford Solar Wind and Energy Project, the Atmosphere/Energy program and a slew of other programs at Stanford are passing solar milestones left and right, and the Stanford Solar Car Team is pushing us closer to the day where we never have to pay for gas again.

And that, oh weather gods, is why it should stop raining.

At least we have a lake this year. Let Jack know if you have a rowboat at [email protected].