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Renewable Energy is Intermittent not Unreliable

(Yes, there is a difference…and it is fossil fuel plants that are becoming unreliable)

A decade ago, forces against renewable energy would bemoan the high cost of renewables. Critics claimed renewable energy would always be too expensive for the average consumer, that it would never be a financially feasible form of energy. Today, now that renewables are the cheapest form of energy generation, there is a new line of attack: unreliability. Renewables might be cheaper, the detractors say, but the unreliability of the energy source will cause black-outs and brown-outs across the grid and will fail when need is the greatest.

The fact is, renewable energy is not unreliable, but intermittent; similar sounding, but vastly different when it comes to load balancing and attracting investors. An unreliable energy source would imply that we are uncertain of the output potential of renewables; an opposite of the truth. With advances in technology over the last decade, we are now able to forecast with a high degree of certainty both short-term and long-term production potential. Modern meteorological data now allows us to better forecast days ahead and allows predictions of seasonal potential solar and wind energy. This intermittency (not unreliability) has created new mechanisms for monetizing energy and new investment opportunities.

The intermittency of renewable energy is creating an opportunity for energy storage. Energy storage technologies, such as batteries, can store excess renewable energy during times of high production and then release it when needed. Meaning, when renewables are producing over grid capacity, that over-capacity can be stored for later with energy storage technology. Investors in energy storage are then able to use the highly accurate forecasts mentioned earlier and monetize the fluctuations in production to make investment decisions knowing with a high degree of certainty how many days and hours energy storage systems will be used and the price potential for stored energy during those times. This helps to smooth out the fluctuations in renewable energy production and ensure that there is always enough electricity to meet demand. As the cost of both renewable energy and battery storage have dropped, the demand has greatly increased. The chart below shows the growth of queues of US grids for different forms of production and storage.

Source: Berkeley Lab review of interconnection queues

These advances in energy storage technology and renewable production forecasting, give credence to the growing investment in the energy transition. The detractors claim of unreliability is shown to be untrue. In actuality, many fossil fuel facilities are becoming unreliable.

A greater challenge for the grid has been the decreasing reliability of traditional base load plants. Base load plants such as coal, natural gas and nuclear were constructed to provide a large amount of power with few shutdowns and startups annually. The rise of low-cost renewables has made that structure a thing of the past. Instead, base load plants are regularly being shut-down during periods of high renewable energy production and being restarted when renewable production drops. In competitive markets where lowest price generating assets win market share, more expensive base load fossil fuel plants are struggling to fill the new need for those facilities. Simply put, the low cost of renewables is paving the way for the end of high-cost fossil fuel facilities.

The greatest impact has been felt by coal plants, some of the oldest plants in the US. Researchers at the NREL estimate that coal power generation plants were built with the expectation of having warm and cold shutdowns a few hundred times during their generating life; instead, they will have closer to 2,000 shutdowns during a plant’s life¹. This has caused increasing rates of metal fatigue and other challenges. In turn, during times of high coal plant production demands, coal plants have a forced outages rates nearing 10%². This has created grid challenges. To address this issue, we will likely need to see more aggressive action on modifying the grid to accommodate intermittent renewable energy including increasing use of battery storage that was mentioned earlier. Also, the grid can be made more flexible to handle more variable loads (EV’s will likely play a part in this balancing but is a discussion for another time). Additionally, new grid balancing practices, such as demand response, can be used to manage demand and reduce the need for peak power production. Longer term we will likely see greater usage of hydrogen for seasonal load balancing since excessive renewable energy could be converted to hydrogen using electrolysis and converted back into electricity using a fuel cell or being burned in converted natural gas plants during seasons of high demand but limited renewable potential.

With careful planning and integration, intermittent renewable energy will be a reliable source of electricity. The technologies and solutions available today make it possible to overcome the challenges of intermittency and ensure that renewable energy can meet our growing energy needs. Renewable energy’s cost efficiencies, technological advances, and intermittency solutions trump the growing unreliability of aging fossil fuel facilities and pave the way for the future.

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