New technology

The festival’s energy and technologies

Most of the festival’s energy was derived from biomass either in its raw form (wood, straw etc.) or refined into biofuel (ethanol, rapeseed oil, etc.).

The energy was generated using a variety of technologies: a Stirling engine, a “Viking”-gasifier, a rapeseed oil generator, second generation bioethanol generators, bicycles and solar panels.


By making the festival energy efficient, consumption was reduced by half. The energy that was needed was met by renewable sources, which made the festival C02-neutral. The energy generated from renewables was fed into the national grid, which stabilizes and optimizes the energy supply.

Stirling Denmark’s Stirling engine

In a basement at DTU stands a two-tonne bright green engine. It provided power to CO2PENHAGEN. In the future it will provide energy for schools, hospitals, villages, and island communities with cheap, carbon-neutral energy.

Every major building with heating needs is a potential customer,’ says Lars Jagd, CEO of the company Stirling DK who made the engine. ‘We make clients independent of fossil fuels and enable them to be self-sufficient’.

The Stirling engine is powered by wood chips, which come from the area around DTU and which would otherwise have been thrown out; quite ordinary garden waste. The incineration does not happen in the engine itself, like in a normal engine, but outside in the fuel chamber.

With the Stirling engine, the flexibility is greater than with a normal engine. All forms of biomass, including organic waste, can be used in the engine. Using almost any local, organic source of energy, it is possible to generate the electricity for an entire building or even a small community.

The biofuel that keeps the Stirling motor running is carbon neutral because the fuel comes from what Lars Jagd calls ‘natural growth’:

When you burn a branch of wood it will emit CO2. But the new branch which grows out will suck a similar quantity of CO2 to itself. In this way, the technology is CO2 neutral’.

When trees and plants grow, they absorb CO2. CO2 molecules are again released when wood is burned. It is part of a natural balance. If you can use energy from biofuels such as wood, straw or coconut shells, it is actually possible to generate power without adding more greenhouse gas to the atmosphere.

According to the European Union, biomass will one day be able to cover half of Europe’s energy consumption. Lars Jagd believes that biomass is the most effective renewable energy source:

Unfortunately, there has been too little focus on biofuels. But now that is changing. Biomass has great potential.’

Rapeseed generator

Rapeseed oil is much less damaging to the environment than the fossil fuels that we use today to keep the engine running. The CO2 released into the air when rapeseed oil is burned in a diesel engine is C02 that has been absorbed from the atmosphere by the rapeseed when the plant was growing. When the rapeseed is harvested, new crops are replanted, thereby making the use of rapeseed oil CO2-neutral.

Although the rapeseed oil has a more viscous substance than diesel, it is possible to make the liquid thinner using the car engine’s cooling system to heat up the rapeseed oil.

At CO2PENHAGEN, the rapeseed oil generator was used for producing energy for the Lounge and the Explore zone. This was fairly simple to achieve since the generator was connected to power outlets with plug sockets to distribute the power.

Absorption cooling

At a traditional festival, cooling normally amounts to 2/3 of the energy consumption. In the Music Zone however, drinks were cooled using absorption cooling, achieved using excess heat generated by the rapeseed oil generators that the festival was using.

At CO2PENHAGEN, energy was employed more efficiently by using surplus heat generated in one process to useful purpose in another. Festival goers could clear their consciences with a cold beer at the bar!

eTenzor bikes

The eTenzor is an indoor fitness bike that was especially adapted for CO2PENHAGEN Festival. Its original features include a very precise workload control and a built-in capacity for a personal handicap based on the user’s individual physiology. This means that people of varying ability levels can train together and achieve a personally effective workout.

For CO2PENHAGEN Festival, the eTenzor was adapted so that energy created as people exercise could be captured and stored in two internal 12 volt batteries and used for the festival.

The eTenzor bike uses the E-core Transverse Flux Machine (ETFM) which is a new mechanical design of the Switched Reluctance Machine (SRM). The new design was developed and patented in cooperation between Aalborg University, Institute of Energy Technology in Denmark and ePower Technology.

The ETFM can be built in small dimensions (diameter/width). It produces a very precise and reproducible resistance and maintains a high torque down to low speed, making it a unique design for fitness applications.

The ETFM and eTenzor bike is designed by AWS Technology, which you can read more about at www.awstechnology.dk 

DTU Viking gasifier


For daily use at DTU the Viking gasifier produces electricity from wood chips. But during CO2PENHAGEN, festival guests’ rubbish was also used, meaning that their waste actually contributed to energy production.

The gasifier produced approx. 10-15 kilowatts per hour, which was exploited in the festival’s venues, bars and food stalls. At CO2PENHAGEN, the gasifier supplied 22 percent of the festival’s energy.

At DTU the gasification plant has been an ongoing project for more than 20 years. The specificity of DTU’s gasifier is that it produces a mixed and exceptionally clean gas, that can be used for burning and does not emit CO2.