One of the greatest concerns facing the implementation of a worldwide 100 percent clean, renewable energy and storage system is whether electricity, heat, cold, and hydrogen will be available when they are needed. In other words, can a 100 percent WWS grid avoid blackouts? The electric grid in a 100 percent WWS world will be very different from that today. Today, electricity comprises about 20 percent of all end-use energy (or 40 percent of primary energy). In a 100 percent WWS world, electricity will comprise close to 100 percent of all end-use energy, which itself will equal primary energy less transmission and distribution losses. The nonelectricity end-use energy will come from geothermal heat and solar heat. The sectors that will be electrified (transport, buildings, industry, agriculture/forestry/fishing, and the military) will use more energy-efficient technologies than with a fossil-fuel system. Such technologies include battery-electric vehicles, hydrogen-fuel-cell-electric vehicles, and electric heat pumps, among others. The reduction in energy use due to the use of more efficient technologies will reduce overall energy demand substantially. Demand will also decrease because no more energy will be used to mine, transport, or process fossil fuels, bioenergy, or uranium for energy. End-use energy efficiency will increase, and policies will encourage less energy use. A future electric grid will also be coupled with electricity, heat, cold, and hydrogen storage. Finally, a future grid will have more long-distance electrical transmission instead of fossil-fuel pipelines. Thus, the main challenge in a future grid will be to match electricity, heat, cold, and hydrogen demand with 100 percent WWS electricity and heat supply plus storage while using demand response. This chapter discusses how to meet such demand both on short timescales (seconds to minutes) and long times scales (months to seasons to years).