COP15 Post | News from the UN Climate Change Conference Copenhagen 2009

By Christina Tækker

Solar, wind and hydro power steal all the attention in discussions about how to limit CO2 emissions, but they are still years away from being ready for widespread use as sources of electricity. And the time it would take to develop the necessary technologies is time that we do not have, according to COWI Department Head Jens Ole Hansen.

If we are to reach the CO2 reduction goals that governments are shooting for, then we need to think differently, and we need to think quickly, Hansen believes. The quickest fix is to tap into the heat created when fossil fuels like coal, oil and gas are burned to generate electricity.

Normally, 40 per cent of the energy contained in fossil fuels is utilised by power plants. The remaining 60 percent goes to waste in the form of heat. Producing such enormous amounts of heat only to release it again is more than just wasteful – it is also totally unnecessary. That energy could be used in district heating networks, but in 90 percent of the world’s power plants it is just let off as hot air, he says.

The potential is enormous: harnessing just 3 percent of the heat generated during electricity production would save as much energy as the amount generated by all the world’s wind turbines combined, he says.

“A light bulb always goes on whenever I see the potential in this,” Hansen says. “We talk so much about renewables that we forget that there’s an enormous unutilised source of energy out there. It does come from fossil fuels, but they are fossil fuels that we are burning anyway.”

Calculations show that if you eliminate district heating from Denmark’s energy grid, the country’s CO2 emissions would rise by 30 percent. That is something that other countries can look to as a model. At the upcoming Bright Green Expo in Copenhagen, COWI will be on hand to spread the word about the potential of district heating by illustrating how much energy six cities in different parts of the world could save by capturing the heat generated by electrical plants.

According to the figures, Dubai could reduce its CO2 emissions by 25 per cent – a total of 2 million tonnes annually. Beijing would cut its emissions by half, a reduction of 13 million tonnes annually.
Hansen believes that a lack of understanding of energy systems and the way in which electricity is generated prevent district heating from being considered as an energy-saving technology.

“But it could also be that politicians love the simplicity of wind turbines,” he says. “They turn and electricity comes out of them. District heating is more complicated. You need to understand how different power plants and energy sources work. What we need is a long-term energy policy.”

While power plants in most countries generate only electricity, the Scandinavian countries have realised how to capture the heat for use in district heating systems and to develop the technology behind it.

When it announced its ambition to become one of Denmark’s first carbon neutral cities, Frederikshavn, in northern Jutland, said it expected to rely only on sustainable fuel sources by 2015. Thanks to its extensive district heating system, doing that will require only replacing natural gas by alternative sources like waste, solar or biofuels.

“The beautiful thing about district heating is that once the pipes are in place, it’s easy to change fuels,” Hansen says. “In terms of infrastructure, that gives district heating an advantage in terms of longevity. If you really want to cut emissions, change from coal to renewables like bio, solar and geothermal. You’ll be carbon-free almost overnight.”