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by Linda Bertelsen
Flying green

Airplanes, trucks, and cargo ships that do not emit CO2. Does that sound like future music to your ears? The Jumbo Jet Denmark is in the air and is on its way to the green future, where DISTRICT HEATING can tie it all together. District heating can ensure that the sustainable future becomes financially sustainable, too! Here you see a little of the HUGE plan that will make Denmark, a pioneer in green energy conversion, become CO2 neutral in 2050 – with district heating as the backbone of it all!

By Henrik Søndergaard, Editor at DBDH

We start in the theory classroom:

The energy is constant. New energy cannot enter the universe, and energy cannot disappear. Energy cannot be used. But energy can change from one form to another. Chemical energy can e.g. change to motion energy and heat (as it does in a combustion engine car). Or when waste burns, becoming heat, producing steam, that drives a turbine, running a generator, making electricity, and so on. We have become adept at directing the transformation from one form of energy to another. To convert energy into the form of energy we need to meet our goals.

But every time the energy changes its form, we say, there is a loss of energy. Of course, that is not true. But we perceive it this way, e.g. when the car uses gasoline and most of the energy turns into heat we can’t use for anything.

In physics, energy signifies the ability to work or heat something.
Energy can be transformed, from one form to another, but neither arises out of nowhere nor is destroyed.
The total energy of the universe is constant.

Here is where the district heating comes into the picture. District heating is brilliant when large energy transformations happen. The largest transformations today are combustion – with CO2 emissions as a negative side benefit.

The district heating (DH) has so far reduced the energy waste from e.g. electricity generation by using surplus heat for another purpose: heating homes, institutions, offices, and everything else.

But right now, new winds are blowing over Denmark to reduce CO2 emissions. Tailwinds for wind turbines and solar cells, and headwinds for the combustion, from which district heating has been so good at utilizing the excess heat.

But with the new winds blowing, new opportunities arise too, when surplus heat from data centers, today emitting as much CO2 as air transport, is to be utilized. Or when the wind energy transformed from electricity to liquid sustainable fuel to be used by airplanes, trucks, and cargo ships! Again, DH becomes the key to utilizing the heat energy from the energy transformation otherwise wasted.

Energy is money.
Wasted energy is money wasted.
With district heating, the energy waste in the inefficient energy conversion processes can be reduced.
District heating can make sustainable energy economically sustainable!

The principle of green conversion of aircraft, trucks, and cargo ships:

  1. Power from wind turbines to produce hydrogen
    – Conversion from electrical energy to hydrogen happens via electrolysis – and a part of the converted energy turns into heat energy. Either, wasted energy, or energy used for DH.
    – Then the hydrogen is compressed to 700 bar to become liquid. Electricity is required here too, and again, much of the electrical energy becomes heat – either wasted or used for DH.
  2. CO2 Capture
    – Carbon capture technology is to wash the smoke to remove the CO2, before leaving the chimney – from e.g. a waste incineration plant or biomass-fired plant. The process requires
    electricity and heat energy – obtained by burning more waste. Again, the excess heat is either wasted energy or energy for DH.
  3. Hydrogen and CO2 turn into liquid fuel
    – By mixing hydrogen (produced by wind turbines) and CO2 (captured from, e.g., waste incineration), environmentally friendly liquid fuel for ships, trucks, or aircraft, can be produced. CO2 and hydrogen are the basics ingredients in the hydrocarbons we currently are pumping up from the underground as oil and gas. To produce liquid fuel, such as eFuel, an energy conversion developing heat energy – is either wasted or utilized for DH.
Figure: www.audi-mediacenter.com – post edited by DBDH

Figure: www.audi-mediacenter.com – post edited by DBDH

This far so good – enough about the theory. Here are a few high-profile examples of green transition planning, being launched in Denmark, and where sectoral integrating and district heating are to ensure it all becomes cheaper and greener.

Giant plants in Copenhagen to produce 250,000 tons of eFuel

Some of the largest Danish energy and transport companies are now joining forces to develop a plant to produce sustainable fuels, based on wind power.

  1. The first stage is a 10 MW electrolysis plant, to produce hydrogen for buses and trucks, in 2023 already.
  2. The second stage, ready by 2027, is a 250 MW plant, expected to be powered by a new offshore wind farm offshore Bornholm in the Baltic Sea. Hydrogen will be produced at the plant, combining CO2, captured from point sources in Copenhagen, e.g., from the ARC waste incinerator you can read about below. The aim is to produce methanol for maritime transport and jet fuel, so-called e-kerosene.
  3. The final stage is to be ready in 2030 and exploit the full potential of the new offshore wind farm. The electrolysis capacity increases to 1.3 GW and enough captured CO2 to produce 250,000 tons of fuel annually. This can replace 30% of the fossil fuels used at Copenhagen Airport. Full completed, the plant will replace 250,000 tons of fossil fuels for road, sea, and air transport, saving the environment for 850,000 tons of CO2 annually.


eFuel indicates electricity is part of an electrolysis process creating hydrogen, followed by another process step, in which the hydrogen is combined with CO2 to produce liquid fuels such as methanol, gasoline, diesel, or aviation fuel. The processes are called Power-to-Liquids (PtL).

Denmark kills two climate birds with one stone

Waste incineration emits a large amount of CO2. And from the political debate, one could very well get the impression waste incineration is the greatest environmental sins of all. But that picture is misleading.

At a modern waste cogeneration plant, the energy in the non-recyclable waste is utilized while protecting the environment. Spreading the modern incineration method globally, hence waste not thrown in a landfill, will represent a global environmental and climate quantum leap.

One of the world’s major environmental culprits is waste in landfills. Waste landfill leads to methane emissions, a greenhouse gas 23 times more powerful than CO2.

In 15 of the EU’s 28 member states, more than 50% of the waste is landfilled. And the picture only gets worse in a global perspective.

Population growth is exploding, cities are turning into metropoles, and waste in ever-increasing quantities is being dumped in a landfill to harm the local environment and global warming. Estimated the amount of waste worldwide will increase from 1.3 billion tons per year discarded in 2012 to 2.2 billion tons in 2025, but that figure may prove much higher. The vast majority will end up in a landfill.

But not in Denmark. Talking about waste, Denmark is – with good reason – regarded as a small light in the dark, in an ocean of garbage. Particularly, concerning sorting the waste and utilizing the energy resource, in the combustion of the non-recyclable part, Denmark stands out to the rest of the world.

Through waste incineration, Denmark has killed two climate birds with one stone. Denmark has taken out landfills from the equation and can now, with new technology, capture CO2 from waste incineration plants, and use it as a resource for producing sustainable fuel.

Amager Ressource Center. Illustration: BIG

Amager Ressource Center. Illustration: BIG

Carbon capture technology can capture CO2 from incineration plants, energy utilizing waste.

Focusing on reducing the amount of waste, and sorting the waste for plastic, incineration of the non-recyclable waste is a necessity.

The alternative is to landfill the waste, MUCH worse for the environment causing high emissions of the undesirable greenhouse gas methane.

Carbon Capture at a waste incineration plant in Copenhagen

Amager Resource Center (ARC), the owner of CopenHill (the cover image), burns the non-recyclable waste to produce electricity and heat for the capital region. The smoke is cleansed from more than 99% of the harmful particles, so the smoke is mostly water vapor – and a lot of CO2. The ARC emits 480,000 tons of CO2 annually, of which 160,000 tons are so-called fossil CO2, resulting from the burning of plastic.

In collaboration with the five owner-municipalities, ARC has investigated the possibilities to capture CO2 and recycling it. The conclusion is that it is possible – both technologically and economically. The energy to operate the carbon capture plant comes from CopenHill’s production, and the CO2 can be sold – e.g., to the upcoming eFuel giant plant in Copenhagen (see above).

ARC is currently actively working on constructing a carbon capture plant within the next five years, cleansing the smoke from at least 160,000 tons of CO2.

The final decision to build a carbon capture plant is up to the politicians in the ARC’s owner municipalities.

For further information please contact: Henrik Søndergaard, henrik.sondergaard@hotmail.com

“We are currently looking at the possibilities of capturing our CO2. We want to reduce emissions and contribute to Copenhagen's goal to become the first CO2-neutral capital in the world - in 2025. Despite all the green transition efforts, there will be garbage. So, we are searching for solutions to reduce our CO2 emissions.”

Meet the author

Henrik Søndergaard
Editor, DBDH
“Fly GREEN!” was published in Hot Cool, edition no. 2/2020. You can download the article here:
Fly Green! Hot Cool article no. 2, 2020