PopSci.com welcomes back Dr. Bill Chameides, dean of Duke’s Nicholas School of the Environment. Dr. Chameides blogs at The Green Grok to spark lively discussions about environmental science, keeping you in the know on what the scientific world is discovering and how it affects you – all in plain language and, hopefully, with a bit of fun. Now, PopSci.com partners with The Green Grok to bring you exclusive new blog posts a week before they hit the Grok's blog. Give it a read and get in on the discussion!
First, a recap of last week's post: In the late 19th century Thomas Edison pushed for a distributed system to deliver electrical power. His dream was never fully realized. Instead, George Westinghouse’s system designed circa 1891 took shape and forms the structure of today’s grid: a centralized system.
Today’s Grid: What’s Wrong
While it’s based on his vision, Westinghouse might not recognize our current grid -- a vast system of some 16,000 power plants connected by hundreds of thousands of transmission lines carrying electrons to millions. Collectively, every year we consume more than 4,000 million megawatt-hours of electricity (see figure 1 here for a breakdown of energy sources).
We’re used to electricity on demand. We expect the flip of a light switch to produce instant illumination. To accomplish this, we’ve organized our electric grid into three wide-area, synchronous grids: an East, a West, and a Texas grid (it’s special I guess).
Why synchronous? And why not national? It all has to do with that pesky alternating current (AC), in which electrons move back and forth. Here’s the thing - you can’t just plug different power plants, windmills, or regional grids together. For an AC grid to work, all electrons everywhere on it must switch direction at exactly the same time or else it crashes and everyone loses power. Accomplishing this over the entire country would be a tall order given the technologies currently employed. So we synchronize each of the three grids independently and then connect them together using high-voltage direct current (HVDC) trunk lines.
While it’s been enormously successful, many believe that a computerized, adaptive system (a so-called “smart” or “intelligent” grid) could do better. I see four key issues the smart grid could address.
Why We Need a Smart Grid: Four Big Improvements
1. Reliability - Our complex grid involves untold numbers of switches and substations connecting power plants to households and businesses whose electrical demands rapidly fluctuate in time. Unfortunately, the grid is highly sensitive to small variations in voltages and/or the timing in which the electrons change direction (i.e. phase).
Relatively minor events like snowstorms and thunderstorms, can result in local blackouts – not a foreign experience. But when a local failure triggers a cascade of failures, blackouts can roll across entire states – think August 2003.
To address such problems, the smart grid will be “self-healing,” meaning that problems will be detected, isolated, and fixed in real-time with little or no human intervention.
2. Two-Way Interactivity – Current in the grid itself flows in direction – power is sent from plants. The grid doesn’t monitor consumers’ real-time usage (or even their generating contributions from solar cells or wind turbines). To ensure that there’s enough power to meet all needs, power companies always keep excess capacity on hand; this extra electricity is thrown away except on rare instances when demand peaks. Not very efficient. A smart grid would interact with homes and their smart appliances, adjusting power supply and demand in real-time to maximize efficiency while guarding against system overloads.
3. Flexible Transmission System - The current grid is designed for generating facilities typified by coal-fired plants: always operating at or near capacity. It’s Westinghouse’s system. But it’s predicated on a worldview of plentiful energy resources, where inefficiencies and waste are acceptable. That worldview no longer applies. Dwindling fossil fuel supplies and global warming concerns demand renewable energy sources such as wind and solar, resources that tend to be:
Putting more renewable sources of energy into our current mix (see pie chart) requires a hybrid grid that combines the best features of centralized and distributed systems.
Such a flexible grid would use intelligent systems to handle a wide variety of power sources and storage systems while also maintaining stability.
4. A National Electron Superhighway - Finally, our transmission system must be able to send power efficiently around the nation. Why? Consider wind. The Midwest has much of this potential resource, but people are concentrated on the East and West Coasts. We need a way to get that energy to the people with a minimum of resistive losses. So we must replace outmoded trunk lines (that connect our regional grids) with a single high-voltage transmission line that crosses the nation incorporating nodes along the way that allow individual sub-grids or generating stations to plug in. To minimize resistive losses, this new transmission line will probably be a high-voltage direct current (HVDC) line.
Great Idea but …
It’s easier to talk (or blog) smarter than it is to be (or act) smarter. Building the smart grid poses challenges.
One issue is money. Estimates put smart-grid costs in the ballpark of $65 billion over the next decade or two. The $11 billion from the stimulus package is a start, at best.
Then there’s jurisdiction.
While the need for a smart grid is a national priority, questions of jurisdiction will rise, say, when the installation of a national transmission system is announced and you learn the lines will be strung through you neighborhood.
Ultimately, getting a smart grid is about more than smart technologies; it’s also about figuring out how to be a smart society. The latter might prove to be a lot more difficult.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.