Thermophotovoltaics

Project Title: Multi-scale modeling and design of efficient thermophotovoltaic systems

Project Dates: September 2021 - Present

Collaborators: Alina LaPotin, Colin Kelsall, Kyle Buznitsky

Location: Atomistic Simulation & Energy Research Group, Massachusetts Institute of Technology

Project Summary:

Instead of capturing light from the sun like traditional photovoltaics (PV), thermophotovoltaics (TPV) absorb light emitting from a heat source. This improves reliability as TPV can operate at any time of day. Further, while solar PV cells cannot absorb light below their band gap, TPV circumvents this issue by reflecting sub-bandgap light back towards the thermal emitter, recycling their energy instead of losing it. Thus, TPV has the potential of vastly outperforming solar PV technology.

There are a couple of fundamental questions that arise from above. First, how do we ensure all of the sub-bandgap light is reflected? Some of our collaborators are working on designing high-reflectivity back-surface reflectors. However, there is also some parasitic losses within the PV cell itself. The first part of this project investigates the impact of free-carrier absorption on sub-bandgap absorption using atomistic simulation techniques. Given a TPV cell architecture, the goal is to predict the influence of each layer of the highly-doped tunnel junction on overall sub-bandgap absorption, which helps guide optimization of cell design.

The second question is how to generate heat for the TPV cell. Traditionally, the Atomistic Simulation & Energy lab has combined a thermal energy grid storage (TEGS) system with TPV. TEGS acts as a thermal battery, storing heat generated through resistance heating of a heat-transfer fluid. Another possible heat generation mechanism is through combustion. The second part of this project focuses on efficient combustor design, using computational fluid dynamics (CFD) with chemical reaction kinetics to model conversion of chemical energy into heat. The goal is to design a combustor with low heat loss and high efficiency, to act as a cheaper and potentially more efficient alternative to fuel cells.