This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
I have received many interesting questions from readers in response to last Sunday’s article “Controlling the Path of Least Resistance with Smart Wires.” This week, I consolidated these questions and took them back to Smart Wires - the start-up company behind the power flow control technology that was featured in the previous discussion – to get their response. Their answers are below.
But first, to quickly re-cap – According to reports released over the past 6 months, the Tennessee Valley Authority (TVA) and Southern Company have successfully deployed networks of distributed power flow control devices to relieve stress on the nation’s electricity grid. These reports document findings from two on-going large-scale projects that could represent an economic option for solving a national grid modernization challenge.
The core technologies used in these projects were developed by Smart Wires, an aptly named start-up company based in Oakland, California. This company was one of the first technology start-ups funded by ARPA-E under their Green Electricity Network Integration (GENI) Program.
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Question 1 - Do you need to put this power flow control technology on every power line in the transmission grid? Or is a portion (1/3) enough to have *almost* complete control?
Every system is unique with different constraints and requirements. While it depends heavily on the electrical network, it will often be the case that some key transmission lines will benefit more from Smart Wires technology and have more impact on the remaining lines in the network than other lines in the system. Deploying Smart Wires on a single line can often have disproportionate impact on the entire grid. For example, we’ve seen cases where deploying on a single line can allow sufficient power transfer to avoid building a new power plant. It usually makes sense to deploy on the lines with the highest impact on grid resiliency (or to solve a particular problem) and then proceed with additional lines until the benefits do not justify the costs.
Question 2 - In the TVA project, there were 100 PowerLine GuardiansTM installed for 7.5 miles of transmission line. Is this an indicative device/length ratio that you expect to apply to future projects?
The device/mile ratio seen at the TVA installation is reasonably typical. This ratio is determined by the characteristics of the line (e.g. voltage, Ampacity, conductor size, etc.) and the amount of impedance change required. The number of devices scales with the compensation requirement, a typical ratio ranges from 3 to 30 devices per mile.
Question 3 - Any idea how long it would take to manufacture enough of these Guardian devices to have them on all of the country’s most stressed power lines?
Smart Wires has robust manufacturing capability that is designed to rapidly scale with market acceptance and demand. Ubiquitous deployment will not follow a simple timeline because the nation’s grid is constantly evolving creating greater need and new opportunities for this technology.
Question 4 - Could this PowerLine Guardian technology help to facilitate the integration of many small power producers into the grid (which was originally designed for a few large ones)?
Smart Wires’ distributed power flow control technology provides flexibility and situational awareness previously not available to transmission operators. This unique combination is critical to optimizing the transmission system to accommodate future generation profiles, whether sourced from distributed power producers or centralized plants.
Question 5 - What are currently the main barriers to having this technology deployed across the U.S. power grid?
As is the case with any technology being introduced to the utility industry, the technology must be proven to be reliable and valuable to ensure that the utilities are able to fulfill their mandate to deliver reliable and low-cost power to consumers. As a device exposed to the elements, the Smart Wires units must be able to withstand and operate properly under harsh environmental conditions. The new technology must seamlessly integrate with the existing equipment and control software used to operate the network. Smart Wires has followed a path to demonstrate to the industry that its products meet these requirements through its successful pilot deployments and software integration. Greater awareness and comfort with the reliability and multitude of benefits that this new technology provides are the most important necessities for quickly reaching wide scale adoption.
Thanks to those who sent questions in response to Sunday's article and to those who take the time to read our posts here on “Plugged In.”