We depend on electric power like we do the air. Without electricity our society could not function. For something so important, we all benefit from learning a bit more about why the electrical system works so well, how electricity moves through the grid, and how wind and solar power help to keep our grid secure and reliable.
A new report, “Powering into the Future: Renewable Energy and Grid Reliability,” offers us a plain English explanation of how electricity powers the grid. Would you like to be able to say, “renewable energy generation can help stabilize the load shape by providing reserve margins, controlling voltage by adding and absorbing reactive power, and providing frequency control …” and know exactly what you’re talking about? If you answered yes, this report is for you.
Prepared by the respected energy consulting firm M.J. Bradley & Associates, the report offers a short course in electricity generation and the benefits of integrating renewable energy resources into the grid. It includes three key chapters and a brief “reader’s guide,” all with well-researched and documented data. Oh my, the data!
This is heaven for those who want to learn more about how electrons move around on the grid, especially electrons generated with wind and solar power. The story begins, “In the Great Plains, the Southwest Power Pool set a record in early 2016 by using wind to provide 49 percent of power needs. In California, renewables often served the majority of state electric needs in 2015…” And here’s the starting premise: “Wind and solar are the fastest growing sources of electric power – growing, on average, a staggering 14 percent per year between 2009 and 2015 – and accounted for 61 percent of all new capacity added in 2015.”
News flash: Southwest Power Pool recently set a new North American record for wind power running on the system. On February 12, 2017, wind reliably supplied 52.1 percent of total customer demand in the early morning hours.
The basics of a reliable electric grid
The first section is a high level primer of the grid. It reads like a cool textbook. The report delves into what “load shape” means, which is the pattern of electricity demand governed by the seasons, time of day, infrastructure failures, security issues, weather emergencies, and climate change – all conditions that have the potential to stress the perfect balance between supply and demand necessary at all times to deliver power and avoid blackouts.
As the authors point out, our grid has evolved from a centralized system into one that is more like a web. Running it smoothly requires “new and advanced lines as well as increased coordination among generators, transmission and distribution system grid managers, and consumers.” The authors explain how the alphabet soup of agencies and entities work together to maintain the real-time balancing of load (customers like you and me) with supply (power plants, storage, and other sources of electric energy).
The authors also note that the grid is always changing, and they discuss the earlier integrations of nuclear and natural gas, the expansion of the transmission system, and the rise of coal power – all of which occurred without disruption.
Plugging renewable energy into the grid
After explaining the grid’s basic operation, the report delves into how wind and solar power integrates reliably into the grid. The authors first establish the baseline clean energy levels: As of mid-2016, more than 75 gigawatts (GW) of wind capacity and 15 GW of utility scale solar were operating on the high-power grid (not including rooftop solar).
Another news flash: Utility and rooftop solar grew a whopping 95 percent in 2016, exceeding all other resource additions. 14,626 megawatts of utility-scale and rooftop solar were added to the grid in 2016, which is 39 percent of all new capacity additions. (Gas added 29 percent of new capacity, and wind 26 percent).
Wind and solar power share far more similarities than differences with fossil-fueled coal and gas power. One key difference, however, is that while the largest operating cost for fossil power plants is the fuel they consume, wind and solar projects rely on freely available and renewable resources of the wind and sun. Their primary cost is the initial capital cost of construction. Add the benefits of lower maintenance costs, no supply and waste disposal issues, and less moving parts to wear out. Boom! Well, maybe “woosh” and “aaaahhhhh.”
So what changes to the grid could be necessary to really scale up renewables to a majority of all the power on the grid? For one thing, more “flexibility.” No, I don’t mean more yoga. A flexible power grid can quickly and precisely maintain a perfect supply-demand balance in the face of changing wind or cloud conditions that affect the power output from wind farms and solar panels.
For example: Fast-responding battery storage units can almost immediately increase and decrease their power output onto the grid to match changes in output from wind and solar generators. In contrast, large coal plants need minutes or even hours to increase or reduce power to match supply with changing demand. (It’s a little like the differences in acceleration and braking responsiveness between a Tesla and an SUV). It’s a constant dance that many newer resources, like next-generation gas and wind turbines, energy storage, and even the hot water heaters in our homes, can perform more adeptly than old power plants.
To maintain a reliable grid, it is important to continue strengthening the system of wires, transformers, and substations that move power around the country. The report notes that larger power markets spread across states and regions can help to quickly integrate renewables across large regions to balance out supply and demand. To use an example from the report, let’s say you have solar panels in Arizona generating more power than needed there. The system can transmit the power to Wyoming when that state’s wind power is low.
And now for the “wow” alert posed by the report’s question “how much renewable electricity is possible?” The Department of Energy’s National Renewable Energy Lab estimates that naturally occurring energy sources could contribute over 200 terawatts of installed power capacity across the country. That compares with just over one terawatt of all generating capacity installed today. In other words, we currently are using only about 0.5 percent (!) of the total power potential of renewable energy resources.
Of course, the near term technical potential is far less than the long-term theoretical potential. But even here, one of the report’s most potent facts is that the current technical potential of renewable electric power in the U.S. far exceeds total customer demand. This fact even takes into account transmission system constraints and geographic and land use limitations.
Renewable energy can help grid reliability
Finally, the report explains how wind and solar power contribute to a reliable electric system with “reliability services.” For example, it describes how wind and even solar power can provide “reactive power” to help maintain the necessary voltage on the power grid – which is necessary to deliver high quality power to charge our mobile phones and power our TV screens.
Another of the report’s key points is that wind and solar power need little or no additional backup power, known as “reserves.” While seemingly counterintuitive, all of the resources on a large system help to balance each other out in real time. If the output from a wind farm drops unexpectedly, other resources immediately pick up the slack. (That’s done most easily on a flexible system). Sudden failures from large, non-renewable power plants can require more reserves because the grid operators will need to quickly fill the hole with a large amount of electricity.
I’ve given you just a taste of the learning in MJ Bradley’s new report on renewables and reliability. I’ll dig more deeply into each of its major findings in upcoming posts. In the meantime, pour a cup of coffee or tea and start reading!