Eastern U.S. Grid Can Handle 30 Percent Renewable Energy -- And That's Just the Start

The Intertubes are buzzing over a new Energy Department report that predicts renewable energy can crank up the entire eastern United States power grid, to the tune of 30 percent. That's pretty good news for businesses hoping to burnish their green cred by accessing more wind and solar energy.

What's even better news is that the figure of 30 percent is not the ceiling for renewable energy in the eastern states. It is a benchmark used by the Energy Department to predict how the gigantic Eastern Interconnection -- one of the largest power systems in the world -- will handle an increasing load of wind and solar power.

So ... how will the Eastern Interconnection do it?

30 percent renewable energy is just the beginning

The new study, called the Eastern Renewable Generation Integration Study, deploys the Peregrine supercomputer at the Energy Department's National Renewable Energy Laboratory to model the Eastern Interconnection.

The supercomputer angle is important because NREL wanted to look at the massive grid in close detail, down to intervals of five minutes. Previous studies only went down to intervals of one hour.

The resulting study clocks in at a whopping 234 pages that covers 5,600 electricity generators and more than 60,000 transmission lines, stretching into parts of Canada and tapping at the door of the western U.S.

The new study isn't just meant to show off what Peregrine can do with thousands of variables. It is a cost-based planning tool designed to help utilities and other stakeholders absorb more renewable energy into the grid.

So, how did the eastern U.S. do?

Grid suppliers and operators need to anticipate demand and adjust their sources accordingly, while also maintaining a reserve supply for contingencies. The larger the grid, the more complex and challenging it becomes to keep the power flowing seamlessly.

One key issue for any power grid, no matter what the source, is how to handle fluctuations in demand. Traditionally, the method of choice is to construct "peaker" plants that can be powered up quickly when needed.

Natural gas is currently the fuel of choice for peaker plants. Advanced, utility-scale storage for wind and solar energy is also emerging as an option.

Another emerging option is the "virtual" power plant, in which a network of energy consumers and generators use smart technology to coordinate their actions with the needs of the grid.

In addition, the availability of new transmission lines is a key variable.

With that in mind, the new study looks at four different ways in which the Eastern Interconnection could perform with less power generated from fossil fuels.

The research team used a benchmark date of 2026, in anticipation of a significant growth in renewable energy within the next ten years.

That's a pretty reasonable prediction, especially now that Rhode Island has established the first offshore wind farm on the Atlantic Coast.

Basically, the study confirmed something that has become obvious: more renewable energy means that grid operators will have to react quickly, and frequently, to variations in the amount of available wind and solar.

That means the Eastern Interconnection will experience faster, and more frequent, changes in power flow across a huge portion of the U.S. and part of Canada.

That's a pretty tall order, but the study found that all else being equal, the Eastern Interconnection can handily accommodate more wind and solar:

Looking at a year of operations at a 5-minute level, [the study] shows that the power system can meet loads with variable resources-like wind and solar-in a variety of extreme conditions.

"Extreme conditions" refers to a maximum renewable energy penetration of 60 percent during a five-minute interval.

The study has some other findings of interest. As one may anticipate, it found that the penetration of 30 percent wind and solar would be matched by a 30 percent reduction in coal and natural gas combined. The result would be a cut in carbon dioxide emissions by 33 percent over the one-year period modeled in the study.

That sounds, great. The research team cautions, though, that the study deals narrowly with the technological capabilities of the grid. In effect, the model demonstrates how the grid can perform under ideal conditions. There is much work to be done in order to achieve those conditions:

However, technical feasibility depends on other transmission and generation operators providing the necessary ramping, energy, and capacity services; wholesale market design changes; and various capital expenditures, all of which will have financial and other implications that may need to be addressed and were outside of this study.

In other words, policymakers are going to have to get busy!

More wind and solar for the U.S.

The new NREL study is an open source tool, available free to the power industry. It's probably going to get a lot of use. According to the U.S. Energy Information Agency, in 2004 renewable energy accounted for just 4 percent of new electricity capacity.

As the cost of wind and solar began to fall rapidly, that figure jumped to 57 percent of new capacity by 2013.

The cost of wind and solar is continuing to fall in the US, partly due to improvements in energy harvesting technology. The growth of the renewable energy market also means that production volumes are rising for solar panels, wind turbines and other equipment. That leads to an economy-of-scale effect that has also put downward pressure on the cost of wind and solar.

Image (screenshot): Eastern Interconnection via U.S. Department of Energy, National Renewable Energy Laboratory.