# Harvesting the electromagnetic energy confined close to a hot body

## TL;DR

This paper reviews how high electromagnetic energy densities near hot objects can be harnessed using near-field effects like photon tunneling to improve energy harvesting with infrared photovoltaic cells.

## Contribution

It presents a comprehensive review of recent advances in near-field electromagnetic energy harvesting techniques near hot bodies.

## Key findings

- High energy density near hot bodies due to evanescent fields
- Potential for surpassing vacuum energy density by orders of magnitude
- Feasibility of transferring energy to infrared PV cells via photon tunneling

## Abstract

In the close vicinity of a hot body, at distances smaller than the thermal wavelength, a high electromagnetic energy density exists due to the presence of evanescent fields radiated by the partial charges in motion around its surface. This energy density can surpass the energy density in vacuum by several orders of magnitude. By approaching a PV cell with a band gap in the infrared frequency range this non-radiative energy can be transferred to it by photon tunneling and surface mode coupling. Here we review the basic ideas and recent progress in near-field energy harvesting.