Internet of Things

At DTU Energy, we research green IoT devices powered by surrounding energy sources. By converting light, vibrations and waste heat into electricity, IoT devices can be recharge automatically and operate autonomously and remotely without the need for battery replacement.


What is Internet of Things

In Internet of Things (IoT), devices are connected over a network without human-to-human or human-to-computer interactions. With more than 25 billion IoT devices to date and a rapid increase forecasted to reach tens of trillion devices in 50-100 years, it is a key component in the fourth industrial revolution. Despite each IoT device typically using little power (µW to mW), their large quantity has led to the prediction that IoT may be the most energy-consuming system that has ever been created by mankind.

Powering IoT devices

IoT devices are primarily powered by batteries or wired to the existing power grid. Battery powering requires periodic battery change and the extensive use of disposable batteries raises environmental concerns. Wiring is cumbersome, expensive, and only finds its merits in places with easy access to the power grid.

Green IoT devices

At DTU Energy, we:

  • Explore how to harvest energy from ambient sources (heat, light and vibrations) to make green and self-powered IoT devices. We use thermoelectricity to generate power from waste heat, solar cells to harvest light, and piezoelectric generators and magnetic ally inductive harvesters to turn vibrations into electricity.
  • Study novel solid-state batteries to efficiently store the harvested energy in IoT devices in a rechargeable and safe manner.
  • Develop new sensors and actuators such as magnetic field sensors and electrostrictive actuators.
  • Combine extensive knowledge of material science with numerical modelling on the atomic scale and device level to understand and improve energy harvesting.


Dennis Valbjørn Christensen

Dennis Valbjørn Christensen Senior Researcher Department of Energy Conversion and Storage Mobile: +45 20961946