Helen Tunnicliffe writes in TCE Today about a presentation made by Henrik Lund to a major international audience. While we have heard much about Denmark’s success in sustainable energy, it is well worth taking this fresh look.
Denmark aims for 100% renewable energy
Henrik Lund of Aalborg University, Denmark, has told the 21st International Congress of Chemical and Process Engineering (CHISA) that Denmark will be able to switch to 100% renewable energy by 2050.
Lund was presenting a plenary lecture at CHISA, in Prague, and said that the switch will require a holistic approach looking at so-called “smart energy systems”, not just considering electricity generation but heating and transport as well. The Danish government’s ambitious target was set in 2006 and includes these three key uses of non-renewable energy. The government has set several interim targets, including that 50% of energy will come from wind by 2020 and that no power plants will burn coal and no households will use oil for heating by 2030.
The Danish government has had a long history of efficient energy planning after the oil crisis in 1973, and Lund said that there was almost universal cross-party support for the 100% renewable goal. Energy consumption is already stable, but achieving the government’s ambition will need more than just reducing the energy demand and improving the efficiency of energy production.
Currently, around 30% of Denmark’s electricity comes from wind, while 50% comes from small-scale combined heat and power (CHP) plants. The CHP plants not only provide electricity, but heat to homes and businesses in the local area. This ‘district heating’ is much more efficient than individual houses having their own boilers.
Lund noted that the supply of wind-generated electricity occasionally exceeds demand. As the share of wind energy in the Danish electricity grid increases, solutions will have to be found to prevent this energy from being wasted. Many exist, such as simply turning off the turbines, shutting down CHP plants, producing hydrogen or greater adoption of electric cars, but the challenge is choosing the best. For example, shutting down CHP plants would mean no district heating supply, leading to households installing their own boilers or using electric heating and undoing all the good work.
“If you solely look at electricity, then you will say to yourself that there are imbalances between wind and demand and so on, and you identify solutions like electricity storage, batteries, or flexible demand, or you may even build transmission lines to neighbouring countries, but if you broaden this to include heating and transportation and so forth, then you have more options to balance,” said Lund.
Transport has been a major issue, according to Lund. Electric vehicles are not suitable for everything so liquid fuels will still be necessary to supplement these. Biomass and biofuels will be able to meet some of the demand, but not all. Lund’s solution is to use excess energy in the grid to produce hydrogen, but not for use in fuel cells, but to hydrogenate some of the bio-derived oils directly to produce synthetic fuels.
“This is not something we are doing for the sake of the wind turbines, this is something we need to do for the sake of transportation,” said Lund, adding: “Yes, there are energy losses, but those losses are something we will have to deal with because otherwise we cannot satisfy the transportation needs.”
Lund says that the “smart energy system” will not require any need to store electricity, which is very hard, as excess energy will be stored in the form of heat and liquid fuels.
“To conclude, we have identified a route to 100% renewables with wind, and only the amount of biomass that we think we have for this purpose. When we take a smart energy approach, where we also look at power-to-heat and power-to-gas, then we find a way where we can completely balance the system,” said Lund.
Energy in Demand - Sustainable Energy - Rod Janssen 