Tackling big problems, as I’m sure you’re been told, requires thinking outside the box. Even if the box is vertical, chilled, and full of tomorrow’s dinner.

“Ten years ago, this was heresy – putting a door between the product and the customer!” said George Parmenter, the sustainability manager for Hannaford Supermarkets, gesturing at glass doors on a row of coolers in one of the Manchester stores.

Self-closing doors can save as much as 70% of electricity used by vertical coolers in supermarket aisles but can also get in the way of somebody looking to grab a tub of hummus. Hannaford loves to spend less on electricity but also loves to sell food, so what should they do?

Give it a shot and see what happens.

“We tried it, and found it didn’t affect sales,” said Parmenter. Now the company is in the process of adding doors to many coolers, including some floor models, in its 184 stores throughout the Northeast, including 36 in New Hampshire.

The doors are a very small part of the company’s three-pronged approach to reduce the impact of its energy use as part of its goal of becoming a “net-zero carbon” company by 2040. That term that can be vague but is nonetheless admirable and it brought me to tour the store on John Devine Drive to see what Hannaford is doing.

Their electricity approach goes like this: Step one, reduce usage. Two, get all your electricity from renewable sources. Three, convert non-electric uses such as heat and transportation to electricity.

This is a common three-step dance for industries seeking to reduce their climate impact but it’s a very complicated dance, requiring a thousand different actions.

The first step, reducing Hannaford’s electricity usage, is an ongoing project that will never end. It requires installing cooler doors and “nightshades” pulled down over coolers after hours when doors haven’t been installed; capturing latent heat from the refrigeration units to be used to heat the store; switching to LED lighting that get automatically dimmer during quiet hours; optimizing restocking schedules to reduce time that freezers have to be open; and lots of other stuff I didn’t ask about.

The second step is getting the most attention right now, since Hannaford has made a much-publicized pledge to use 100% renewable electricity by 2024, which isn’t far away.

This will be helped by rooftop solar such as the 50 kilowatt array atop this store. That’s a nice array – 10 times the size of my rooftop panels – but it produces at most 5% of the building’s annual usage.

A power-hungry industry like supermarkets can’t begin to offset electricity use with on-site solar, not to mention the fact that Hannaford leases many of its buildings, which complicates the ability to put things on the roof. (They own the store I toured, hence the panels.)

So the company’s main thrust is buying contracts from or investing with large solar projects, mostly in Maine, Massachusetts and New York. Not so much in New Hampshire – since we’re way behind.

Hannaford says it already covers 30% of its electricity usage through agreements with more than 30 community solar projects, but it will need to roughly triple that figure in two years to reach its goal. That push will provide financial heft to build more solar.

Finally there’s joining the “electrify everything” movement, shifting as many fuel-burning applications as possible to electricity. Two electric-car chargers for customers in the parking lot is a tiny step but there’s a very long way to go. The Manchester store is hooked into the natural gas system and switching away won’t be cheap.

Further down the road, there’s the problem of so-called Scope 3 emissions, which are created by all the vendors that Hannaford uses. If the company buys food from a firm which uses diesel trucks in inefficient ways then it has a small responsibility for that pollution and can, in theory, use its financial muscle to force their supplier to clean things up. Easier said than done, however.

And then there is all the non-energy-and-emission pollution that any company produces.

Hannaford is ahead of the pack in one area: Since last year it says it has sent no food waste to landfills, either giving it away to needy groups or composting it. Dealing with plastic is a tougher obstacle.

Grocery stores are loaded with plastic, most of which gets thrown away at home as soon as the contents are removed. Since plastics are almost impossible to recycle in any meaningful way, despite the little triangle-made-of-arrows stamped on everything in sight, the only solution is to find alternate materials.

Parmenter talked about experiments to replace some of the plastic boxes of baked goods with a formed-fiber product based on wood pulp, but even if that succeeds the lid will stay plastic because customers want to see what’s inside.

Parmenter said the company’s public stance on environmental issues is percolating through the nuts and bolts of operating a sprawling company like Hannaford Supermarkets.

“People who make requirements and do store planning – it has shifted their thinking. It’s not always ROI,” he said, referring to Return On Investment, a measure of business action that is almost always limited to dollars and cents. “The calculus has changed.”

The push can also help attract and keep employees, especially younger ones, and that’s important these days.

But in the long run, Parmenter admitted, not even a big company can make a noticeable dent in the effects of climate change.

“We know that Hannaford going it alone is not going to make the difference … that one grocery chain, all grocery chains, alone can’t do it,” he said. “We have to try.”