Welcome to the December edition of The Direct Energy Buzz!
As we marvel at the glow of holiday lighting, it’s amazing to note how much of our electricity now comes from solar, wind, and energy storage. It’s even more astounding to consider how much technological development has come to light in just the past three months. So this month, we will discuss a big discovery about sub-atomic structures in solar panels, new energy generation set by Texas wind turbines, and how abandoned oil and gas wells might be converted to sources of clean renewable energy.
Since first being used in 2009, calcium titanium oxide -also known as “Perovskite” – has been found to be even more efficient at converting sunlight to electricity. And the stuff is proving to be a key element for cheap, easy-to-make solar panels. The stuff can be sprayed onto surfaces, keyed to different colors (even made transparent), and printed onto solar cells with a thin film backing to create flexible solar panels.
Hybrid organic inorganic perovskites (HOIPs) have been developed to have the highest energy conversion efficiency rating in the industry. Over the past seven years, that has increased from 4 to as high as 22 percent. By comparison, a car’s gasoline engine thermal efficiency at turning burned fuel to usable energy averages about 20 percent.
Theoretically, the highest amount of energy that can be converted from sunlight (called the Shockley–Queisser limit) is about 33 percent. While perovskite-type solar panels right now average between 11 and 18 percent, developers are confident they can double that efficiency in just a few years.
The Past, Present, and Future of the Technology
Previous solar panel technology relied entirely on perfect crystalline structures to produce electricity efficiently. The little defect can deflect and scatter the sunlight before it can be captured and converted to electricity.
Perovskites are littered with numerous defects, yet they work more efficiently. In order to understand why this happens, researchers at Columbia University experimented with HOIP’s.
- In a solar cell, sunlight energizes electrons to move from the cell’s light collecting area to the electrical energy collecting area.
- As the electron moves across the cell, it loses some of the energy it picked up.
- This occurs at a known rate in standard cells but in HOIPs cells, the rate of energy loss is slowed down by over three-orders of magnitude —producing more energy per electron.
- The researchers found that in HOIPs solar cells, electrons are carried past the numerous defects by the formation of “large polaron” structures that both slows down the cooling of electron energy and screens the charge carriers from bumping into the defects.
The problem with HOIP’s is that not only do they contain highly toxic lead, but they are also water soluble. Consequently, they’re not ready to be mounted on top of roofs in the rain. They’ll just wash away. So, the next step in making this technology viable is to understand how the high efficiency of the perovskite can be replicated with durable and more environmentally friendly materials.
Wind Generation Sets New Records in Texas
On November 28, 2016, wind power in the ERCOT region of Texas provided a record 15,033 MW of electricity to the Texas grid, about 45 percent of total demand. Wind energy development is currently at more than 18,000 MW and with another 5,000 megawatts under construction.
The state also has 2,000 MW of solar power in use and another 685 megawatts is also expected to be installed. To top it off, only half of the coal-fired plants in Texas are profitable, and ERCOT estimates about 5,000 MW will retire in about five years.
Nationwide, wind energy development costs are expected to decrease by more than 10 percent by 2020 and may fall even lower (by more than 35 percent!) by 2050 as off-shore projects begin. Meanwhile, China is the current world generation leader in wind power with 114.364 GW of installed capacity (the US has 65.628 GW). The largest on-shore wind turbine model is the Gamesa G132-5.0 MW. A single one of these units can generate enough electricity to meet the demand of 5,000 households for a year.
Pumped Hydro Goes Underground
Quidnet Energy recently completed its first field demonstration for underground pumped energy storage in Erath County, TX, and the results for the technology were promising.
The idea is to pump water down into abandoned oil and natural gas wells — not to be used for fracking or to chase out remaining fossil fuels — but to store it under pressure. The idea is similar to large pumped storage reservoir systems only it’s underground and uses existing wells. By using electric energy made via renewable solar and wind sources and then pumping water into the ground at night when rates are cheap, the water is then used to spin turbines and generate electricity during the day when demand (and rates) are higher.
In other words, Quidnet is using spent oil wells as big underground batteries for solar and wind energy.
While it’s true the system uses a huge amount of water, no chemicals are used (such as those in fracking) and no waste water is created, because the same water can be pumped into the ground again and again. Because the water usage is in a closed loop, they can even use non-potable, reclaimed, or impaired water.
For the system to work, it needs geologic formations with very low permeability so that the water doesn’t seep away while in storage. Other problems include faults and fractures that also allow the pressurized water to escape. Finding optimal locations is the tricky part of this technology, as the Quidnet field demonstration worked well – until it encountered an underground fault and pressure fell.
The next step for Quidnet is to build a commercial-scale demonstration plant sometime in 2017 to generate 5 to 10 MW of electricity.
Do you have any suggestions for future installments of the Direct Energy Buzz in 2017? Share with us in the comments!