It’s easy to imagine that electricity from different sources flows through the lines, humming along to different tunes, depending on whether it’s from a coal-fired or natural gas power plant or say, a wind farm or solar array.
Too bad that’s not actually the case.
When thinking about how electricity from different sources travels through the grid, it’s helpful to compare the system to a lake, Michael McDiarmid, a 20-plus-year veteran of the New Mexico Energy, Minerals and Natural Resources Department who initiated the state’s wind power program 13 years ago, says. Ask anyone what is happening with wind development in New Mexico, and most defer to McDiarmid.
Imagine different streams feeding and draining a lake, and campers all around dipping their cups into the water.
“The electrical grid is like that,” McDiarmid says. “It’s fed by different streams—lines—and there are electrical feeders from different generators.”
From any type of generating plant, the electricity needs a way to get to customers. Transmission lines run from the plant to larger lines—those humongous towers you might have compared with alien monsters as a kid—that deliver electricity to substations. Located closer to cities and large factories, substations distribute power toward individual customers and areas. The interconnected transmission lines that deliver electricity from multiple sources are typically referred to as the “grid.”
|• Owned by NextEra Energy Resources (formerly Florida Power and Light), the New Mexico Wind Energy Center near House, NM, was the third largest in the world when built. In recent years, New Mexico ranked within the top 10 for the number of installed megawatts from wind. Now, it stands at 16.
• Under the enacting legislation, three of New Mexico Renewable Energy Transmission Authority’s board members (nmreta.org) are appointed by the governor, one by the speaker of the House of Representatives and one by the president pro tempore of the Senate. The remaining three members include the state investment officer (or designee), the state treasurer (or designee) and the cabinet secretary for the Department of Energy, Minerals and Natural Resources.
• In addition to financing projects through bonds, RETA can offer a letter of support showing that the board has reviewed the project and believes its completion would benefit the state or the region as a whole. The developer can then use that letter of support to solicit input from other investors. The authority also can enter into what’s called a “memorandum of understanding” that pledges additional support to the project.
• There are environmental concerns when it comes to wind farms as well as transmission lines: The huge Altamont Pass Wind Farm near Livermore, Calif., was built in the 1970s along a bird migration route and atop a ridge—causing a regular slaughter of birds.
• The video, “New Mexico Catches the Wind,” can be viewed at the New Mexico Energy Conservation and Management Division website
The challenge for wind farms is getting the electricity from those rural, out-of-the-way, windy-as-hell spots to the existing grid.
“Once in the grid, wind energy is just like electricity from other generators,” McDiarmid says.
Boosters of coal power point to how inexpensive that electricity is—approximately 4.8 to 5.5 cents per kilowatt hour—but McDiarmid counters that those older plants are already paid for, and they don’t meet many modern pollution-control requirements.
If new coal plants were built today, he says, they wouldn’t be as cheap. Construction costs would be much higher and developers would have to install equipment to control pollutants.
Wind power is “clean, domestic and inexhaustible,” and, McDiarmid says, economical. The cost of building a wind farm is comparable to building a coal-fired power plant. But, he adds, a wind farm can be built more quickly, and built of any size to suit the market and its electricity needs. Not only that, but there aren’t any concerns about fuel costs or how they might fluctuate in the coming years.
As for the issue of intermittency—the wind doesn’t blow at a constant rate, and it doesn’t always blow when demands for electricity are greatest, such as on hot summer afternoons—McDiarmid says it’s not that big of a deal.
“We’re not contemplating getting 100 percent of our electricity from wind—the electricity supply already includes a diverse portfolio,” he says. “When the wind doesn’t blow, there is [generation from] natural gas, biomass, solar—and coal and nuclear will be in the mix for a while.”
Right now, McDiarmid says, the issue is transmission. The electrical grid has been neglected for some two decades—and was never designed for today’s demands.
“People have been transmitting large volumes of electricity—and that’s risky because the grid was not designed to do that,” he says. “It’s the same kind of issue with renewables: There are a lot of resources, both wind and solar, but they are not necessarily close to where the load is.”