A DC hybrid micro CHP with battery backup using lead-acid batteries

Agenda for
5-9 September

Joseph Cilia
Professor, University of Malta
Combined heat and power engines (CHP)systems have been employed and used for several years in various heat and power applications. These CHPs mainly run-on fossil fuels, however combined with other renewables and heat pumps, they present an interesting compromise to solve the reliability issue of renewable energy availability. These units can also prove essential to forward the de-centralization of power distribution which leads to higher flexibility, and reduced overall power-losses. Furthermore, the waste heat produced is utilised and the consumer can also be independent from the grid. The authors present a micro-CHP that has a D.C output with an integrated bank of smart VRLA-batteries, allowing it to act as an effective backup energy storage for domestic use, whilst allowing independent starting and islanded operation.

The authors will show results of their CHP in conjunction with PV panels and a two-way smart-inverter, capable of supplying, and sourcing power to and from the grid. The proposed setup includes sub-systems running on DC rather than AC, since most appliances now have inbuilt inverters allowing them to also run-on DC. The mCHP proposed in this paper which has the size of a standard domestic appliance will open up a new large-scale market for VRLA batteries since the backup storage needs to be extremely safe and reliable especially if the unit is fitted indoors in places such as the kitchen. The authors use the VRLA batteries for backup, but it also makes use of space and water heating/cooling as storage, reducing the need of larger expensive battery storage.


Professor Joseph Cilia holds a PhD from the University of Nottingham and is a lecturer at the University of Malta. In 2003, he became the CEO and Research Director of the Abertax Group and in 2010 the Chairman of Abertax Executive Board. He is now the Abertax Foundation Chairman. Professor Cilia’s research interests include high-speed drive systems, electrical transport, and the efficient use of energy and renewables.