Which Energy Technology has the Lowest CO2-Footprint?

Florian Bauer
Published in
3 min readJun 4, 2019


Renewable energy technologies must take over the global energy generation quickly, so that we achieve the 2 °C goal and prevent the tipping of our planet’s climate. But which energy technology has the lowest CO2-footprint, i.e. which energy technology is the cleanest?

Smoking chimneys of a coal power plant.

Wind or solar-PV power plants do not emit CO2 during energy production. However, energy is required to actually produce the materials a wind turbine or a solar-PV module is made of, CO2 is emitted during transport of components and deployment, and the power plant has to be dismantled at the end of its lifetime. The remaining parts also need to be disposed of or recycled. The amount and kind of materials as well as the lifetime differ between the different energy technologies. The same is true for coal or oil powered plants, except that these also emit (massive amounts of) CO2 during electricity generation.

Analyzing the overall impact of a product is called life-cycle assessment (LCA). For a meaningful comparison of the CO2-footprint between energy technologies, the following (simplified) equation can be used:

CO2-footprint = all CO2 emissions over the complete lifetime of the power plant divided by all electricity which is generated over the complete lifetime of the power plant

The CO2-footprint is given in grams (g) CO2-equivalent (CO2-eq) per kilowatt-hour (kWh).

Note that unless really no CO2 emissions occur at any time of the life cycle of a power plant from cradle to grave (or from cradle to cradle), a power plant does have non-zero CO2 emissions. Though, the more renewable energies are deployed and fed into the grid, the lower the production-based CO2-footprint becomes. For example, if a solar-PV module is produced with a high amount of renewable energy, its footprint is lower than if its production was powered by coal.

The following list compares the CO2-footprints of various energy technologies in descending order:

  • 1,178 g CO2-eq per kWh for lignite.
  • 1,044 g CO2-eq per kWh for hard coal (UCTE).
  • 502 g CO2-eq per kWh for grid mix (UCTE).
  • 321 g CO2-eq per kWh for a Diesel generator.
  • 20 g CO2-eq per kWh for solar-PV (rooftop in Switzerland).
  • 17 g CO2-eq per kWh for wind power (2 MW offshore at Danish coast).
  • 7.5 g CO2-eq per kWh for nuclear power (UCTE).
  • 5.5 g CO2-eq per kWh for hydro power (UCTE).

The data is taken from the Idemat2016 database (which is based on Ecoinvent v3.2).

We calculated the CO2-footprint of kiteKRAFT systems. The results are:

  • 4.7 g CO2-eq per kWh for our 10 kW kiteKRAFT system. (This is a 4 m wingspan simplified version of the 20 kW system shown on our website.)
  • 3.3 g CO2-eq per kWh for our 20 kW kiteKRAFT system.
  • 0.6 g CO2-eq per kWh for a projected 4 MW kiteKRAFT system. (This corresponds to a 40 m wingspan onshore-optimized/low-wind-optimized system.)

Based on our calculation, already the smallest kiteKRAFT system — which is comparatively inefficient (the larger the kite the more efficient) — has the lowest CO2-footprint compared to all exisiting technologies. Larger kiteKRAFT systems have even lower CO2-footprints, due to efficiency increases caused by nonlinear aerodynamic effects.

Our calculation is based on simplifications, but was audited by the consultancy firm Quantis. The results already allow to conclude that kiteKRAFT systems have potentially the lowest CO2-footprint there is and therefore the best positive (or lowest negative) impact on our planet’s climate.

For further details and updates you can check out our website www.kitekraft.de and follow us.