Despite U.S. natural gas production continuing to set records, U.S. natural gas prices spiked. The Financial Times reported that natural gas prices jumped 16 percent in one day – their biggest one-day gain in eight years.

The jump in prices came as concern grew that a cold close to November, driving increased heating demand, would draw heavily on natural gas storage. Stocks of natural gas in storage happen to be at their lowest levels in more than a decade.

There’s a lot to unpack here and much that seems counterintuitive. If the U.S. is the world’s largest natural gas producer, and if U.S. gas production continues to grow, why is gas storage falling and the price of natural gas jumping? It’s an interesting conundrum.

Part of the answer – a big part – has to do with eroding fuel diversity in the nation’s electricity mix. As coal and nuclear power plants have been forced into early retirement by electricity markets gamed to their disadvantage, our reliance on renewable power and natural gas has grown. Consequently, natural gas is being used to meet an ever-growing share of the nation’s electricity demand, particularly during summer when air conditioners are humming. More natural gas use during summer means less natural gas is going into storage for use during winter when its needed to fuel both power plants and heating.

Historically, summer has been a time for gas companies to catch up and inject excess production into storage for use during the winter. But increased summer demand for gas is reshaping that equation and it foretells pain for consumers.

A smart column in Forbes points out, “We simply can’t meet winter gas demand without storage. The extreme but perfect example of this was January 1 of this year, ‘the coldest day of the century.’ We devoured a record 143 Bcf/d of gas, yet we produced just 72 Bcf/d of gas that day, or almost exactly half of what we used.” It’s a savvy observation that even as gas production ticks up – driven on by the shale revolution – our demand for it is growing just as quickly and far quicker than the buildout of natural gas infrastructure, be it pipelines or natural gas storage.

We are shifting from a power grid dominated by inherently fuel secure sources of power – both coal and nuclear plants have months of fuel on site – to a grid increasingly dependent on the whims of the weather (think renewables) and just-in-time fuel delivery for natural gas. That shift is raising important questions about grid reliability but also about unnecessary risks to consumers.

As our reliance on natural gas grows, and as electricity markets and entire regions of the country lose their fuel diversity, the potential pain from natural gas price volatility rises in tandem. Increased gas production will be no cure-all. Demand for gas is only poised to soar driven by a growing fleet of natural gas power plants and rising exports. U.S. natural gas export capacity is going to triple by the close of 2019 and then only continue to grow.

A diverse power mix has long shielded consumers from the effects of fuel price surges for power generation. As the price of one fuel would rise – say natural gas – markets would turn to lower cost options relying more on alternatives to keep electricity prices in check. But in key markets, the coal capacity that could always be counted on for balance is either gone or going. It’s a potential economic catastrophe of our own making.

Consider the essential role coal plants played last winter in the northeast. During peak periods of cold, when natural gas demand spiked to meet heating demand, many natural gas power plants couldn’t run. Coal plants came to the rescue. According to the U.S. Department of Energy, coal plants met 55 percent of increased power demand.

Fuel diversity has been an unsung strength of the U.S. energy equation. An IHS Markit study from last year found that our diverse mix – now very much in jeopardy – lowers the cost of electricity production by around $114 billion per year and reduces the variability of monthly consumer electricity bills by around 22 percent. The lead author of the study wrote, “It is easy to take the cost-effective diversity of the current U.S. electric supply portfolio for granted.” She couldn’t have been more right.