ABSTRACT
It is very relevant to take on the challenge of working with the ‘smart cities’ of the future by including a strong plan for implementation of solar energy, which makes it possible to widen the concept into ‘smart solar cities’. This is a strong vision when you take the extremely high reductions in costs into account, both for solar PV technologies and for solar thermal. Recent PV cost reductions actually mean that PV systems can prove a better economy today than off-shore wind turbines. There is also strong support for the practical implementation of solar energy technologies in relation to the much-increased low-energy building demands in Building Regulation standards both for new-build and large renovation projects. In Denmark the most advanced low-energy building standard is the low-energy class 2020 standard, which is the Danish definition of a ‘nearly zero-energy’ building standard. This is approximately 25 per cent better than the low-energy class 2015 standard, which is already a demand in many Danish cities, and the general attitude is that the increased low-energy quality from the low-energy class 2015 to 2020 will to a large extent come from local use of renewable energy solutions, and here the use of solar energy is the most obvious solution. The green solar cities vision is based on the universal relation between the necessary initiatives you need to work with for the future. That means energy savings in both new-build and renovation are the first thing you need to introduce and optimise. When this is done you should look first to an optimised energy supply solution and second investigate how solar energy can be utilised with a high contribution in connection to this, e.g. making nearly zero-energy or plusenergy building possible. The lack of focus on performance documentation in practice is still an important barrier here. In connection to the finalisation of the Green Solar Cities Concerto project in Copenhagen and Salzburg, the situation is that important steps have been taken but it can be concluded that solar energy solutions in buildings are still in most cases an exception. For Copenhagen a positive development has been seen, but there is still reluctance towards it from decision-makers – important architectural and engineering companies talk about how they want to avoid these solutions. In Copenhagen the municipality is positive concerning solar PV, but only sees it
as a very small contribution to CO2 reduction. They prefer to avoid solar thermal because their district heating company has the old-fashioned attitude that it does not fit well into combined heat and power. In Salzburg they have not really taken up solar PV yet, but they are very strong with respect to implementing solar thermal systems and they integrate them both in district heating and in relation to combined heat and power, due in particular to their many years of use of a special energy-point financial system for social housing. However, for both cities solar energy solutions are still not mainstreamed yet. When large building projects are started, both architects and builders will normally not integrate solar solutions from the beginning, but rather see it as an add-on, e.g. to fill gaps in reaching a Danish low-energy class 2020 standard, which you have to live up to in Copenhagen in relation to municipal buildings or new urban development areas. This is a policy which it is hoped will be maintained, even though a new proposal for changing the Danish Planning Law has recently been proposed. Due to having the highest energy costs in Europe since the early 1980s (except for industrial organisations), Denmark has a unique opportunity to be a frontrunner in the necessary transformation to a renewable-energy-based society. The result of this policy, where the politicians decided to keep the costs of oil, gas and electricity high via taxation as a result of the second oil crisis in the early 1980s has led to a situation where Denmark has a clear leadership in the use of district heating, with 55 per cent of buildings utilising this, often together with combined heat and power as well as wind energy, which is now covering around 30 per cent of yearly electricity production. Another not so recognised result of the situation with high energy prices is that solar energy solutions have started to penetrate the energy market on a large scale. During the last ten years we have seen a large number of solar thermal plants being connected to the widespread district heating systems in Denmark, typically covering up to 20 per cent of the yearly district heating demand and without any kind of subsidies, and in some cases covering up to 50 per cent of the yearly district heating demand when coupled with large seasonal storage solutions. For the PV electricity market, which has been kick-started by German feed-in tariffs from around 2000, there was not much happening in Denmark based on a yearly net-metering scheme (which was also used for the wind turbines in the beginning), but when huge reductions in PV costs emerged in the last few years there was suddenly a situation in which PV systems could be installed with good economy for the users, something which especially one-family house owners became aware of. The result was that where there was an almost non-existent market in 2010, a small market was established in 2011 with 12 MWp, and this rocketed to approximately 500 MWp PV installations in 2012. This is something that had to be handled politically in an energy system like the Danish one, because energy taxes are a big part of the state budget every year. Very quickly complaints were made by Danish Energy, a cooperative of energy-producing companies, about one-family house owners who invested in the allowed up to 6 kWp PV installations, and in fact could avoid any electricity bills for the next 30 years, even though
they needed to utilise the common electricity network, especially during winter when there is not so much sun in Denmark. The politicians were unaware of this situation in early 2012 when they signed a long-term energy strategy aiming at transforming Danish society into a 100 per cent renewable energy supply society, mainly based on off-shore wind energy, by 2035. Here they were only allowing 800 MWp solar PV to be installed by 2020. The situation now is that the yearly net-metering scheme for solar PV has been changed into an hourly based net-metering scheme as part of a smart grid strategy and future PV installations are aimed to have a stronger focus towards housing associations and cities. With the continuous reduction of installed PV costs, the situation in Denmark today is that PV systems in many cases are becoming more costeffective than off-shore wind installations. This situation is still not recognised by politicians, but it creates the opportunity for a basis for large-scale implementation of solar energy solutions in Denmark. Here it is relevant to look at the situation we have in Denmark, where it is being discussed what to do with the CHP-based district heating, when the main source of electricity is wind turbines. However, large-scale use of solar energy provides an opportunity for a win-win situation if it is installed in the form of so-called solar energy combined heat and power, which provides solar heating and solar electricity in a 1:1 ratio, in the same way as the existing large-scale CHP system does. This means operation of the large CHP system can be reduced in sunny periods, saving fuel as a result. Here the challenge is to reach low costs for the solar thermal installations. This has already proven to be possible for large ground-mounted solar thermal plants at total installed costs around €200 per
6.1 Forecast for global energy mix by the Scientific Advisory Board of the German government. Here it is clear that solar power is expected to be the main energy source in the future. This means that implementation strategies are needed today for futureoriented frontrunners.
