A method for ship ballasting includes receiving, at a carbon negative energy storage system, input comprising calcium oxide and water and reacting, within a reaction chamber of the carbon negative energy storage system, the calcium oxide and water to release energy and generate calcium hydroxide. The method includes directing, by the carbon negative energy storage system, the released energy to a requesting end user and providing, by the carbon negative energy storage system, the calcium hydroxide to a marine vessel ballasting system. The method includes releasing a mixture of the calcium hydroxide and ballast water from the marine vessel ballasting system into the ocean to sequester atmospheric CO2.