Transmission Q&A

4.7 Education library / Transmission Q&A

• Why do we need new transmission development?

  Our aging and unreliable transmission system forces customers to pay for increasingly expensive power while keeping cleaner and cheaper alternatives out of the market. Our transmission grid has experienced decades of underinvestment and is now being pushed to operate in ways for which it was not designed. The grid is only as strong as its weakest interconnected link – as demonstrated by the 2003 blackout in the Midwest and Northeast. We need to be more connected with our neighbors, not less.

• Are all transmission lines the same?

  Today’s transmission system relies on a network of high-voltage lines that are capable of transporting electrical energy over long distances. These lines come in different sizes, ranging from the more common 64 kV to 345 kV to the more modern and more efficient 500 kV to 765 kV lines. The amount of power that can be sent over a transmission line is limited, so the larger lines are able to transport greater amounts of energy over longer distances while minimizing land use.

• Aren’t DC lines more environmentally-friendly than AC lines?

  Alternating Current (AC) vs. Direct Current (DC) refers to the direction in which electrons move across our transmission lines. AC is a wave of electrons flowing back and forth across the lines, while DC is the constant flow of electrons in only one direction. The majority of today’s grid uses AC lines. DC lines are often single lines and therefore some have suggested greater use of DC to cut down on the overall footprint of transmission. However, there are some limitations to DC transmission. For example, DC lines require expensive converters to get their electrical energy onto the grid. Also, AC lines can accept power from multiple generation sources and transmit it to multiple load centers, allowing for much greater energy transfer over longer distances. DC lines do not allow for easy redirection of power in the event of a line outage. AC lines have the ability to balance power to ensure reliability and avoid a cascading effect of power failures.

• Why don’t we put all power lines underground?

  Transmission lines can either be hung above ground or buried below ground. Most transmission providers site new lines above ground whenever possible for reasons of efficiency, cost and maintenance. As a general rule, underground transmission lines are five-to-six times more expensive to install than above-ground lines. Underground lines are also challenging to inspect and maintain. Restoration time is usually several weeks for underground transmission if a line failure occurs. Today, there are approximately 200,000 miles of high voltage transmission lines. All but approximately 5,000 miles of those lines are sited overhead.

• Why wouldn’t we build more local transmission instead of regional and national?

  We are all connected to our transmission system. Electrical power flows via the path of least resistance, meaning the flow of electricity cannot be routed or controlled like oil pipelines or telecommunications. Today’s transmission system of 150,000 miles of high-voltage lines is the backbone of all the electrical energy produced at power plants across the county. The entire country is powered by an interconnected grid that stays in perfect balance. This is despite unpredictable and constantly changing demand fed by thousands of individual and independent power sources. To be effective, our planning process must recognize these realities and look at broad regional energy goals and needs.

• Why do we need to update the grid now?

  Our current energy grid must be updated in order to improve its reliability and efficiency. Our outdated power grid saddles residents and businesses with more expensive energy while keeping cleaner, more affordable alternatives out of the market. The majority of the existing system was built more than 30 years ago and has only received incremental investment since. Today, 70% of the lines and large power transformers are more than 25 years old.

• What happens if we don’t modernize the grid?

  Unless this aging grid is addressed, the basic reliability of the system will be increasingly at risk, as electricity demand in this country is expected to rise 25% by 2030. In addition, the grid doesn’t connect us to the places in the country where renewable energy is most abundant. Without a modern grid, we will never be able to tap the nation’s unlimited supply of renewable energy resources that have the power to ensure our energy security.

• Would a modern grid raise the price of my electric bill?

  Transmission is a relatively small part of energy cost—generally about 11% nationally. What really costs customers and businesses is the current condition of the gird. Our electric grid has suffered from 30 years of underinvestment. We now face mounting reliability issues and increased congestion. And with increased congestion comes inefficiency and higher costs. In 1970, transmission and distribution losses were about 5%. Since then, these losses have increased 90 percent. Inefficiencies have led to major costs for the U.S. economy. Power outrages and power quality disturbances cost the economy about $100 billion annually

• How can transmission help with the development of clean energy sources?

  Our nation’s energy and environmental goals rely on the rapid development and deployment of domestic renewable energy—like wind, solar, and geothermal. All of these sources have enormous potential for growth, but this potential will only be realized with more transmission development. We simply do not connect the places where the wind blows the hardest and the sun shines the most to towns and cities that need the electricity. According to interconnection queue databases, there is currently almost 300,000 MW of wind projects—that’s more than 20% of our electricity needs—waiting to connect to the grid because there is inadequate capacity to carry the electricity they would produce. A study by the Brattle Group shows that an increase in access to the most abundant wind resources will make wind power economically competitive relative to conventional fuels.

• What is a “smart grid”?

  The phrase “smart grid” usually refers to new technologies that give individuals greater information and control over their own energy use.

• Would a “smart grid” remove the need for new transmission development?

  While they are part of the overall energy solution, these technologies do not solve the underlying problem of an aging and congested transmission system. The efficiencies that smart grid technologies would deliver are not enough to make up for a grid that suffers from poor maintenance and underinvestment.

• Why should residents in one state pay for a transmission project built in another state?

  We all benefit with a modern grid, just like we all benefit from our interstate highway system. Even if we never drive on a given stretch of highway, we use products that are trucked over that highway. It is the same with power—we all benefit from greater reliability, efficiency and cleaner energy. Regional transmission is built in segments for the long-term benefit of everyone. Regarding where regional transmission projects are to be built and who would benefit first, it’s important to look at the larger goal of open energy markets benefiting everyone in the long run. It’s not where you start, it’s where you land.

• How does renewable energy fit into the discussion of new transmission?

  No matter which generation sources we want to tap into, clean coal, renewables, nuclear or natural gas—to bring them to the market, we must have reliable, modernized transmission system. A 21st century energy model starts with a robust electric transmission grid that will deliver increased reliability and energy savings for all Americans.

• How will new transmission construction lower the cost of electricity?

  When you want to control costs in any process, you look for areas of greatest expense. Electric generation by utilities makes up about two-thirds of a consumer electric bill—the portion that a competitive wholesale market will shrink while making the power grid more efficient, stable and secure. In contrast, electric transmission accounts for only 11% of the average electric bill, yet provides tremendous value by allowing access to competitive wholesale markets, promoting competition and lowering prices for electric generation.

• So what’s the hold up in getting new transmission built?

  The logjam is a direct result of an outdated patchwork of local, state and general regulations. Planning, cost allocation and siting continue to be impediments to getting a regional transmission grid developed. A 2011 U.S. Chamber of Commerce report revealed that more than 350 energy projects nationwide are stalled as a result of regulatory red tape, including 21 transmission projects. The delay in construction related to these energy projects has cost the U.S. economy $1.1 trillion and has prevented the creation of 1.9 million jobs, according to the report.

• How will the Clean Power Plan affect the future of transmission?

  It’s too soon to tell, but transmission is essential for compliance with the rule, whether at a state or a regional level. Compliance timelines must accommodate transmission planning as part of the implementation. Additional transmission capacity will promote continued reliability of the bulk power system during this transition to a cleaner national portfolio of power generation sources by supporting changes in base power flow, and also will directly support the interconnection of intermittent renewable resources such as wind and solar generation. Regardless of how rulemaking ultimately unfolds, a strong grid will enable greater flexibility in accommodating diverse energy sources across the country.