A method of reducing gray energy consumption and achieving optimal gray energy saving for carbon neutralization is proposed. In a cellular network, each cell or BS, group of cells, has renewable, green, and non-renewable, gray, on-grid power, energy sources. The renewable, green, energy is highly variable and unpredictable, while non-renewable, gray, on-grid power, is stable but is not renewable and thus has more carbon impact. Each cell or BS, group of cells, services is associated UEs when it is on. In one novel aspect, a cell or BS, group of cells, that consumes more non-renewable energy can give some or all of its served UEs to another cell or BS, group of cells, that consumes less non-renewable energy (602, 603).