Earth Day was Sunday, which means that retailers have once again made a round of announcements touting new sustainability initiatives in the last few days. This year, the big theme has been the rollout of more electric vehicle charging stations.

As car manufacturers look to convince more consumers to buy electric vehicles, one of the major hurdles has been the concern about where they can recharge their cars. So they have been working with mass retailers, given their large presence across the U.S., to build out charging stations in their parking lots.

Target and Walmart are among those who have said in recent days that they will add hundreds of such charging stations to their stores.

Minneapolis-based Target, which started piloting charging stations in 2012, currently has them at 18 locations in 5 states (Minnesota, California, Hawaii, North Carolina and Texas), including at its headquarters in downtown Minneapolis and Brooklyn Park. It said Monday that it will add them to 100 locations, amounting to 600-plus parking spaces, in more than 20 states over the next two years

As part of this new rollout, some Twin Cities-based Target stores will also get some charging stations, said spokesman Lee Henderson.

Target's program is in conjunction with partners Tesla, ChargePoint, and Electrify America (a subsidiary of Volkswagen that was created in the wake of its emissions scandal), which will install their charging stations in the parking lots. The new stations will all be the super-fast variety that more quickly replenish a battery's charge than some of the home-based or earlier iterations of charging stations.

"These stations allow guests to go to Target, do their shopping, and come out to a fully-charged car," said Henderson.

Meanwhile, Walmart said last week that it plans to more than double the number of electric vehicle charging stations at its stores by adding several hundreds charging stalls with an aim of having more than 1,000 of them in the coming years. Electrify America is also one of Walmart's partners.