Wind generators or windmills are sprouting up all over the United States.

They're part of a growing move to expand the use of renewable energy sources, like wind and the sun, to produce electricity.

Examples are everywhere. Construction of a 50-megawatt wind farm was just completed in New Mexico. Shovels will break ground in Indiana later this year for an even larger 100-megawatt wind farm. Contracts have been signed for a 49-megawatt solar project inOhio.

Technology companies like Google are investing large amounts in renewable energy, including offshore wind projects along the Atlantic coast, because they recognize that it's the future.

Indeed, renewables have taken off in the United States. Between 2005 and 2009, electricity from renewable sources grew more than 15 percent — and it is expected to grow even more rapidly.

But the expansion of these clean and green resources — and the environmental benefits and economic growth they promise — could be stymied by existing limitations on the planning process for integrating them into the nation's electrical grid.

"The grid" may be an unfamiliar term to many. But it's an apt way to describe the electric system.

In the simplest terms, the grid is an interconnected network of high-voltage lines for bringing electricity from power plants to customers. The grid may be the biggest, most complex machine ever created. It consists of thousands of generators, tens of thousands of miles of high-voltage transmission lines, and millions of customers using electricity.

Our transmission system operates like the country's network of local roads and multilane interstates. High-voltage transmission lines deliver electricity over long distances to distributors, like the local public utility, which reduces the voltage and sends it over lines to customers.

Most of this system was designed and built decades ago. Even though electricity demand is growing at a slower pace, new generation resources are always needed. Today, most of the proposed projects use wind and solar energy. New transmission lines will be needed to move electricity from renewable sources — many in remote locations, far from existing transmission lines — across multiple states to the urban areas where the power is needed.

A new approach to the planning of the transmission grid is necessary to address this problem. Reforming transmission planning will enable renewable electricity sources to more fully contribute to meeting the nation's electricity needs.

For PJM Interconnection and other regional transmission organizations (RTOs), which plan and manage the electric transmission system serving two-thirds of the country's population, the challenge is that rules governing the system generally restrict the transmission-planning focus to preserving grid reliability and relieving bottlenecks on the system that raise electricity prices.

In short, the existing rules for transmission planning don't incorporate public-policy objectives like expanding the use of renewable energy. PJM and its members are considering changes in the planning process and will submit them to the Federal Energy Regulatory Commission (FERC).

FERC, which provides regulatory oversight for RTOs, recognizes the problem and recently issued an order related to what can be done to make it easier to build lines that aren't strictly for reliability and providing for those who benefit from those lines to help pay for them. But there is a lot of hard work ahead for transmission organizations and other planning authorities to comply with the new guidelines.

Delays related to permitting and siting have affected the industry's ability to build new transmission infrastructure for a number of years, according to the North American Electric Reliability Corp., the nation's electric reliability watchdog.

That's not to say that transmission isn't getting built, such as a 500-kilovolt line from western Pennsylvania across Maryland to Northern Virginia that recently went into service. It was authorized under current transmission-planning standards to address the likelihood of future reliability issues.

Transmission planning may not sound exciting, but the stakes are high. Consumers and businesses will face an unreliable electric grid and higher electricity prices — and renewable energy goals could be hindered — if not enough transmission is built. On the other hand, everyone could end up paying for unneeded transmission infrastructure if we build too much.

That's why effective planning by grid organizations is so important — to ensure that the transmission required to meet reliability, economic and public-policy goals is carefully considered and then built to be ready when needed.

PJM has been working with stakeholders to improve the flexibility of the transmission planning process, which is essential to bolstering America's electric transmission system to meet the nation's economic and environmental goals.

Reforming the process for planning and building transmission now will enable power to be delivered where it's needed tomorrow.

Michael J. Kormos is senior vice president of operations at PJM Interconnection. His email is kormosmj@pjm.com.