Novel Method for Harnessing Energy from Heat via Light

A theoretical study describes how diffuse light produced by anything from sunlight to computer screens could be converted into useful energy. 

Physicists from Trinity College Dublin believe their insights into light behavior may provide a solution to one of science’s oldest problems: how to convert heat into useful energy. The study was published in the international journal Physical Review A.

Their theoretical breakthrough, now undergoing lab tests, could influence the development of specialized devices that enhance the amount of energy gathered from sunlight (as well as lamps and LEDs) and repurpose it for useful tasks.

When photons (light particles) are caught in small optical devices, they can condense, causing them to behave collectively rather than independently. In practice, this focuses light energy into a narrow, powerful beam of a single pure color, similar to a laser.

Experiments have demonstrated this phenomenon, but only when the energy input is already in the concentrated form that a laser provides. However, the researchers at Trinity believe it can now be accomplished utilizing input energy in a dispersed form, such as that easily supplied by sunlight or LEDs, according to the new study.

We modelled the behavior of devices which trap light in a small region of space and found that this behavior is related to the general properties of heat engines: machines that convert disorganized energy, which us physicists call ‘heat’, into a useful form, which we call ‘work.

Paul Eastham, Study Senior Author and Naughton Associate Professor, School of Physics, Trinity University

“In this way, the same laws that limit steam engines and power plants determine whether photons condense or not. Beyond the conceptual appeal of this work, we believe it could influence the development of optical devices which rely on channeling the flow of light energy at the quantum level, from solar cells to microscopic engines powered by radiation,” added Paul Eastham.

“The primary goal of such optical devices would be to produce ‘useful’ energy, which would come out as laser-like light. In relative terms, this is easy to convert to other forms, and any applications would involve doing that. For example, it might be possible to combine such a device with solar cells to increase the amount of electrical energy they capture from sunlight,” added Luísa Toledo Tude, School of Physics, Trinity, first author of the study.

“Because the next step is to test the theory in a lab setting we must be cautious not to over-speculate at this point, but of course it is exciting to think this work may one day help us increase the amount of useful energy we can capture from light sources and then put to work to power the millions of things we need it for,” concluded Luísa Toledo Tude.

Journal Reference:

Tude, L. T., et al. (2026) Photon condensation from thermal sources and the limits of heat engines. Physical Review A. DOI: 10.1103/6lyv-trfj. https://journals.aps.org/pra/abstract/10.1103/6lyv-trfj.