Hybridising renewable energy sources

The fluctuating nature of solar energy is one of the major barriers to becoming a bigger part of the energy mix. The EU-funded project 'Hybrid renewable energy converter for continuous and flexible power production' (HRC POWER) is making significant steps toward round-the-clock solar power. Its novel concept relies on a hybrid system that combines a number of renewable energy technologies.

This hybrid renewable converter (HRC) will be heated either by microcombustion that efficiently generates high temperature heat from biogas or hydrogen, or by concentrated solar radiation. The generated heat will be converted into electricity by thermoelectric or thermophotovoltaic effects. Major focus is placed on developing novel functional materials for advanced building blocks that withstand high temperatures, and high-temperature joining technologies.

Researchers have performed thermofluidic and combustion simulations as well as thermal simulations to design components that are able to operate both under solar concentration and internal combustion. Careful consideration has been given to reducing thermal losses and increasing the operating temperatures.

A complete process flow has been developed to generate micro/nano-structured refractory absorber metamaterials based on molybdenum films. Furthermore, researchers have studied various structured metallic materials based on their ability to emit infrared light with energies higher than the bandgaps of existing thermophotovoltaic cells.

Partners have developed two different approaches to develop converters made of silicon–carbide. A new process flow has been defined to realise half or full combustors based on the siliconisation of graphite preforms. Other activities undertaken concern ceramics and metal tube brazing. The first full combustors have been assembled.

All the work related to simulation, design, material choices and assembly activities performed so far has allowed provision of the first fully integrated converters.

HRC POWER developments will especially target the hybridisation of solar and combustion modes to convert solar thermal energy into electricity. Knowledge gained in microcombustion regarding heat loss reduction and the use of catalytic reactions should also be valuable for optimising lean-burn combustion engine designs.