Tyndall has adopted a ‘twin track’ approach to energy harvesting & storage
(i) Leveraging from existing and near future technologies – applying system integration expertise, focusing on strategic application areas based on REAL-LIFE ambient energy sources available. This may include hybrids solutions (e.g. combining different types of ambient energy sources, combining energy harvesting with batteries or other pre-charged energy sources).
(ii) Developing more fundamental disruptive technologies that will lead to medium to longer term breakthroughs for future industry solutions.
Indoor solar energy harvesting
For indoor solar energy harvesting Tyndall’s main focus is on wearable solutions and wireless sensor networks (WSNs) for building energy management (BEM) applications, leveraging from existing industry parts, optimizing selection and combination to minimize load and maximize efficiency of the source.
Indoor solar energy harvesting is a technolgy of particular interest for BEM applications due to the very limited number of ambient energy sources (vibrational, thermoelectric, solar) that exist typically within buildings. At 350 lux indoor solar energy will only deliver about 1-2% of the energy from a typical outdoor solar panel and this may be available only for 8-12 hours/day, possibly only 5 days/week so this very limited energy source must be harvested efficiently and stored with minimal leakage.
Technology efforts and breakthroughs relate to developing smart energy management circuits that minimize leakage, maximize conversion efficiency (max power point tracking (MPPT) and minimise charging time
Sample reference points:- Tyndall has published papers demonstrating
(i) a fast-charge indoor solar panel method for reducing charging time by 33%
(ii) an ultra-low power MPPT & energy management circuit that improves energy efficiency by 30%
(iii) a demonstrator running Tyndall’s WSN mote continuously (120uW) based on 12hrs 350Lux availability and that can run > 72hrs in darkness. (Operates at a 10 minute duty cycle).
Thermoelectric Generator (TEG) Energy harvesting
Tyndall has developed a TEG energy harvesting solution that can operate a Tyndall WSN BEM mote continuously based on a 60deg C temperature gradient (10 minute duty cycle).
Research activities in Tyndall extend to electromagnetic device development in this area. In collaboration with the University of Southampton in EU project VIBES Tyndall has developed the world's highest normalized power density electromagnetic vibration powered energy harvesting solution that can operate a simple WSN mote continuously (~50uW) based on an ambient heat pump vibration. Recently under Dr Roy's leadership, Tyndall is looking in to find the solution of a partinent problem in this area i.e. how to increase the bandwidth of operation with increased power density of a miniaturized vibrational energy harvester by incorporating nonlinear dynamics in to some novel designs. Batch fabrication processes of some of the novel designs are undertaken on Si going from MEMS to NEMS.