SWEDEN An analysis carried out by Vattenfall says yes: Sweden has a good chance of meeting this goal, but a series of challenges litter the path.

Building new nuclear power is expensive and the political uncertainty in the matter makes such investments rather risky. For these reasons, it is very likely that nuclear power will reach the end of the line in Sweden within thirty years.

But what will happen when electricity generation capacity disappears in southern Sweden, where most of the nuclear capacity is found today? How will it be replaced? Where are the bottlenecks in the transmissions grid? How much will the import capacity need to be increased? What will the politicians have to do? And what will it cost?
An analysis by Vattenfall shows how Sweden can convert to a 100 per cent renewable energy system without nuclear power.

“It’s not as if we have developed a detailed plan for the transition, but it is important that we have analysed a scenario which is widely discussed in our society. If we are to phase out nuclear power without increasing carbon dioxide emissions, this must be done in a smart way,” says Helena Nielsen from Vattenfall’s Strategy Department (who just recently moved to Vattenfall’s wind business). She carried out the study together with colleagues from several different parts of the company.

The renewable path
There is no doubt that a solely renewable electricity system can be built in Sweden. The country has three main advantages over the long term: hydro power, large land areas suitable for wind power and extensive forests. So far so good. But that does not automatically solve the carbon dioxide challenge.

“In a renewable electricity system, Sweden would be dependent on imports, including from Poland and Germany, whose power generation is not free of carbon dioxide emissions. Nor could we help the rest of the continent by providing it with CO2-free power to the same extent as today,” Nielsen explains.

The availability of energy is not currently a problem. Sweden generates more electricity than it consumes: in 2014, ten per cent of its electricity was exported. And the current expansion in wind power will contribute to Sweden continuing to have a power surplus for a long time to come, even if this will decline as the nuclear power plants are phased out.

So the big challenge is not merely to generate sufficient energy to meet the country’s needs over the year, but rather to ensure that capacity is available in terms of output, when it is actually needed, such as during the coldest winter days.

Hojum hydro power plant
Hjuleberg wind farm

The challenge of winter
Swedish capacity demand varies over the year from less than 10 GW in summer to 27 GW on particularly cold days that can occur in a “ten-year winter”. In comparison, a Swedish nuclear power plant generates approximately 1 GW.

With an installed hydro power base of 16 GW and the same amount of wind and solar in the future, plus some output from biomass fuels, it all looks good on paper. But even if the wind does blow more during winter than in summer, we can’t be sure it does on the specific day when the power is needed. Therefore the truly available capacity from hydro, wind, solar and bio power would only be 20 GW. This means that another five to seven GW are missing to handle the winter peaks (see chart below).

“One of the most important points shown in the analysis is that we will have to focus a lot more on output and on flexible capacity in the future rather than just talking about energy in general. Compared with today, shortfalls in output and energy may occur more often in a renewable system when demand is high and generation from wind and solar is low.”

Reliable capacity lower in 2050
“Reliable capacity” is the power generation capacity that can be expected to be available due to weather and more. In a future renewable energy system, the figure is lower than today. To avoid shortages, sufficient import capacity, reserve power and demand control is needed some hours per year. The maximum demand in the coldest winter to be expected over a ten-year period is 27 GW.

A mix of measures is needed to solve this equation. Perhaps the most important of these is to expand the transmission capacity in order to make maximum use of hydro power.

“Nordic hydro power offers a series of key system functions. The ability not only to maintain but also to increase its flexibility will be crucial for a successful transition to a renewable system. If hydro power is to make a full contribution, the transmission grid from northern Sweden must be strengthened. In addition, transmission capacity to countries outside the Nordic region must also be expanded in order to allow us to import electricity and thus avoid shortfalls.”

Bio power is an energy source that will most probably grow in importance: partly because it contributes key functions to the energy system and partly because it can be generated close to where the energy is needed. Also it can contribute capacity that is not dependent on the weather.

“We currently use about 40 per cent of our heat capacity, for example district heating plants, to also generate electric power. This is considered to be low from an EU perspective and there would seem to be a potential to increase the share of bio power. That’s why we believe that the installed capacity of this energy source could be higher.”

It will also become more important to manage consumption. A study carried out by Chalmers University shows that the peak load could be reduced by 3 GW by remotely controlling the heaters in the country’s detached houses so that they are not all used at the same time. In Finland, trials have been carried out on steering heat loads in grocery shops remotely.

“We need to work with flexible demand in order to facilitate supplies in peak situations. That would allow us to reduce the need for back-up power,” says Nielsen.

Quicker transition more costly
A fully renewable energy system requires large investments. The actual final sum will depend on how quickly the transition is implemented.

From an economic viewpoint, the most efficient manner would be to keep using nuclear power throughout its full technical lifetime so that the last reactors are not taken out of operation until around 2045. If nuclear power is already phased out in 2030, the costs for the transition could increase by a couple of hundred billion Swedish krona, according to Vattenfall’s estimates. This sum does not include the write-down of the nuclear power plants due to their premature closure.

“If nuclear is decommissioned in advance, we will, in principle, have to pay twice for renewable generation, seeing that wind turbines for instance have to be replaced after 20 years. In addition, it will not be possible to increase the required transmission capacity sufficiently by 2030, which means that the electricity system in southern Sweden will need a back-up, most likely in the form of gas turbines. We also know that the costs decline with time as technology develops. All in all, we think that if we are to set up a renewable system, the transition will need to take time,” Nielsen explains.

Next step 100 % Energiewende
After analysing Sweden and the Nordics, Vattenfall will now look into how a future energy system based on renewables could work in Germany and the Netherlands. The project is expected to be completed by the summer.
“Compared to Sweden, Germany and the Netherlands will be even more dependent on their neighbouring countries in 2050, as there is not as much hydro power. We also expect to see energy storage throughout the power system: in the homes, at solar and wind power sites and in the distribution networks,” says Vincent Otto, project manager at Strategic Development. 

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