Millions of oil and gas wells are abandoned and orphaned around the world. Due to funding shortfalls, many abandoned and orphaned wells remain unplugged and are negatively impacting the environment and contributing to greenhouse gas emissions, such as methane. To reduce emissions and environmental impacts, the wells are required to be plugged but the well sites can be repurposed for wind and solar energy and/or the wells itself can be redeveloped for geothermal energy production. To quantify methane emissions and identify opportunities for repurposing abandoned and orphaned wells and well sites for renewable energy development, we analyze public oil and gas well data from governmental agencies of documented abandoned and orphaned wells in Canada and the United States. We estimate the total number of abandoned and orphaned wells in Canada and the United States to be 3,500,602, of which 4% are orphaned and in need of government funding. We estimate plugging costs for orphaned wells in the United States to exceed federal funding by 33%-80%. For abandoned and orphaned wells, we quantify methane emissions at the national and state/provincial/territorial level and potential emission reductions achieved through plugging. Furthermore, to evaluate mitigation and redevelopment opportunities, we analyze geographic locations of abandoned and orphaned wells with national maps of renewable energy potential (geothermal, wind, and solar) and land cover/land use in Canada and the United States. Mitigating oil and gas wells can help fulfill national energy transition goals and emission reduction targets, while providing an additional funding stream to manage the millions of abandoned and orphaned wells around the world.