Nanowatthours

Nanowatt-hour (nWh) is a unit of energy equal to the energy delivered by a power of one nanowatt operating for one hour. This means 1 nWh is 1 × 10^-9 watt-hours, which equals 3.6 × 10^-6 joules. Since energy is the product of power and time (E = P × t), 1 nW for 1 h corresponds to 1 nWh; 1 W for 1 h corresponds to 1 Wh, or 1 × 10^9 nWh. The nanowatt-hour thus provides a convenient scale for extremely small energy budgets.

Usage and context: The nanowatt-hour is not a standard SI unit, but it is used in fields dealing with nanoscale energy and ultra-low-power devices. It appears in discussions of energy harvesting, persistent sensing, and memory or computation on very tight energy budgets. In such contexts, researchers may report energy consumption or harvested energy in nWh or in related submultiples like nanjoules (nJ) and microjoules (μJ) depending on the time scale.

Examples: If a nanosensor consumes 100 nanowatts for one hour, the energy used is 100 nWh, equivalent to about 3.6 × 10^-4 joules. For a device drawing 1 microwatt for 30 minutes, the energy is 0.5 μWh, which equals 500 nWh or approximately 0.0018 joules.

Notes: Nanowatt-hours are useful for expressing very small energy quantities but are less common than joules or watt-hours in general engineering practice. They are most relevant in nanotechnology, energy-harvesting research, and ultra-low-power electronics.