What do we want for our kids’ future?

In an op-ed piece about Pennsylvania’s electric grid that appeared Nov. 9 in The Express, the writer, Terry Jarrett, argues that coal-fired power plants must be maintained to ensure grid reliability.

I agree with Jarrett that “America’s energy sector has reached an interesting crossroads,” but our future energy needs will be met not by returning to outmoded, 20th century technologies but by embracing what some are calling the “transformative shift” now occurring in electricity generation across the United States.

Globally, we are dumping 34 billion tons of manmade global warming pollution into the atmosphere per year, enough carbon to equal 20 times the weight of the current world’s population. In the U.S., coal-fired power plants are our chief source of CO2 emissions, with a single plant capable of generating 3.5 million tons of CO2 per year. These plants also spew mercury, sulfur dioxide, nitrogen oxides, and unburned particulate matter, causing smog, acid rain, and damage to plant and aquatic life, as well as to human lungs.

Contrary to Jarrett’s claim that coal plants “already employ stringent emissions controls,” plants in Pennsylvania as recently as this past January were cited by Maryland, Delaware, and Connecticut for contributing to poor air quality in their states.

The Pittsburgh Post-Gazette reports that regulators in Maryland argue that 10 years of recorded nitrogen oxide emissions data show that Pennsylvania’s coal plants are either “not running their existing controls effectively or, in some cases, not running them at all.”

Efforts to reduce emissions by employing so-called “clean coal technologies” have not gotten far. The technologies are prohibitively expensive, and energy companies are hesitant to invest millions of dollars in an industry that is clearly in sharp decline. In the face of record-low natural gas prices, coal plants are shutting down, with looming closures in at least 16 states.

Today, the District of Columbia, Rhode Island and Vermont no longer have any coal-burning plants, and five other states each have only one. In Pennsylvania, power generation began moving away from coal and toward less expensive natural gas over a decade ago, years before introduction of the Clean Power Plan.

David Gaier, a spokesman for NRG Energy, which owns several power plants in Pennsylvania, insists that coal will continue to be phased out over time. “This. . . helps ensure that we can integrate renewables,” Gaier states, adding that NRG is committed to increasing its investment in wind and solar, vowing to reduce emissions of CO2 and other greenhouse gasses by 90 percent by 2050.

Which brings us to the matter of grid reliability.

Jarrett contends that, with the decline of coal, “America has lost an unprecedented amount of baseload capacity in recent years,” implying that the grid’s ability “to meet the daily operational needs of the entire nation” is in jeopardy.

He cites Energy Secretary Rick Perry to support his claim. Perry and spokespeople for the fossil fuel industry assert that, unlike wind and solar that generate energy only intermittently — when the sun is shining or the wind blowing — the baseload power supplied by coal and nuclear is the truly reliable choice.

In truth, coal operations are often themselves vulnerable to interruption, experiencing outages 6 to 10 percent of the time due to derailments, freezing, flooding or other natural occurrences, and reportedly failing to meet their maximum theoretical output about 15 percent of the time.

A series of studies — including one conducted by the Department of Energy, which Perry now heads — conclude that, with a well-managed grid, renewables will be well able to supply most of the nation’s future energy needs.

Wind and solar are already cheaper than natural gas in more than 30 countries. Estimates are that Pennsylvania could produce 10 times its current electricity consumption with solar energy alone. According to Michael Drexler, head of infrastructure and development at the World Economic Forum, “Renewable energy has reached a tipping point. It is not only a commercially viable option, but an outright compelling investment opportunity with long-term, stable, inflation-protected returns.”

So what about the ability of renewables to meet our energy demands? The Department of Energy study mentioned above concludes that the addition of renewables to the grid has not compromised its reliability and that “significantly higher loads of renewable energy can be integrated without any compromise of system reliability.” The electricity grid is a complex system in which power supply and demand must be equal at any given moment.

When demand increases, adaptations are required.

Coal and nuclear plants have difficulty adjusting to these fluctuations; they lose efficiency when not run at full capacity, take hours to start and stop, and — in the case of nuclear plants — can be out of service for weeks at a time. In contrast, renewable storage technologies are able to respond rapidly, ensuring that the supply of generation matches the demand, and thus creating a more flexible and reliable grid system.

A variety of storage technologies are currently being developed. With thermal storage, solar arrays can capture heat from the sun and store energy in water, molten salts or other fluids. This stored energy is later used to generate electricity, enabling the use of solar energy even after sunset.

Similarly, excess wind power can be used to create hydrogen, which can be stored in wind turbine towers for generation of electricity when the wind is not blowing.

Flywheel systems have been developed that can both store electricity and discharge it to the grid. And batteries of various sizes can be distributed throughout the grid, thus alleviating congestion in both transmission and distribution and enabling storage on a large scale. As more renewables are added to the grid, our energy supply is becoming more flexible, resilient and, yes, more reliable.

Standing at this crossroads, we have a choice.

We can hang back, clinging to damaging, outmoded ideas.

Or we can move forward, knowing with increasing confidence that, in the future that we are leaving to our children and grandchildren, the lights will be on, the air will be clean, and this planet will still be home.