The conversion of electrical energy into thermal energy using technologies such as resistive heaters, electric boilers and heat pumps, sometimes coupled to thermal storage, for space heating, industrial heat processes or short‑term energy storage and grid flexibility services.

Principle

Electric‑to‑thermal conversion provides a high‑availability sink for surplus electricity and can yield effective COP>1 when using heat pumps; it trades electrical energy for immediate or stored heat, thereby shifting demand in time and providing demand‑side flexibility but increasing instantaneous electrical load where deployed.

Demonstration

Illustrative scenario → A district heating plant integrates an electric boiler and a large hot‑water tank. Recognition → Forecast surplus wind power during low demand. Action → The operator runs the electric boiler to store heat in the tank for evening demand. Consequence → Reduced renewable curtailment and provision of dispatchable heat, offset by conversion losses and higher local electrical peak loading when charging occurs.

Misapplication

Assuming all P2H routes are inefficient because they “waste” electricity; this ignores that heat pumps can deliver greater thermal energy than the electrical energy consumed (COP>1), and that thermal storage often has lower cost per stored kWh than batteries.

Consequence

P2H can absorb variable renewable generation, decarbonize heat demand where electricity is low‑carbon, and provide ancillary grid services, but it increases aggregate electrical energy demand, may require grid reinforcement at peaks, and its emissions impact depends on the carbon intensity of the electricity supply.

Reversal

When grid electricity is carbon‑intensive or very expensive, using electricity for heat can increase emissions or cost compared with direct use of low‑carbon thermal sources; conversely, when electricity is very low‑carbon, P2H reduces sectoral emissions. Also, decentralized small‑scale P2H may have different economics than large, centrally controlled systems.

Boundary

Clearly within: resistive heaters, electric boilers and compression/absorption heat pumps used to produce space or process heat, optionally with thermal storage. Boundary case: cogeneration that simultaneously produces electricity and heat—this is not P2H per se but can interact with P2H systems. Clearly outside: conversion of electricity to gaseous fuels (P2G) or chemical feedstocks (P2X) without thermal output.

Semantic Tension

P2H improves renewable integration and heat decarbonization but raises peak electrical demand and grid costs; planners must weigh heat sector decarbonization against the need for generation and network capacity.

Synthesis

P2H is a rapid, often cost‑effective way to convert surplus or low‑carbon electricity into useful thermal energy; its system value depends on technology choice (resistive vs heat pump), storage integration and the carbon and temporal profile of the electricity supply.