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So far Leandra has created 35 blog entries.

Silkeborg: Record-breaking solar district heating plant in operation

2018-06-11T15:45:12+02:00Jan 25th, 2017|

In Silkeborg, Denmark, the world’s largest solar thermal plant has been delivered at the end of 2016 as planned. With 156 694 m² this new record-breaking plant is more than twice the size of the largest until now in Vojens, also delivered by Arcon-Sunmark in 2014.

In the past seven months, a truck has been loaded 445 times with solar collectors at the Arcon-Sunmark headquarters in Denmark in order to make the one and a half hour drive to the construction site. The 12 436 collectors are connected to the district heating system of the city.With an annual yield of 80 000 MWh the system will cover the heating requirement of 4 400 average households or 20% of the annual demand: ‘One fifth of Silkeborg’s annual heating consumption from now on will be covered by solar heating, and we are proud to be part of the project together with Silkeborg Forsyning. It is a proof of how swiftly a transition to renewable energy can be executed and that the process does not have to be long and time-consuming,’ says Søren Elisiussen, CEO, Arcon-Sunmark.

The contract between Silkeborg Forsyning and Arcon-Sunmark was signed in February 2016. In May the construction began, and at the end of December the installation was put into operation.

Source: Arcon-Sunmark

Solar district heating made in Denmark – since 1988

2018-05-17T11:16:19+02:00Jan 24th, 2017|

In Denmark more than 1.3 million square meters of solar collectors are connected to district heating. A map as well as the summary of this success story of solar district heating is now available on a webpage.
In the last 10 years in Denmark, the annual growth in the total collector area has been 42 % in average. Similarly, the average increase in the number of district heating plants with solar heating has been 29 %. A number of plants choose to expand their solar capacity after a few years, and so far 16 plants have increased their existing solar thermal capacity – some even more than once.As always there are some significant uncertainties in the planned development. However, a new version of the agreement between the Danish Energy Agency and the main Danish energy supply companies stating the level of energy savings each sector must realize within a certain timeframe has been adopted in December 2016. In the previous agreement there was a time limit for how long SDH could count as heat savings (2016) but the new version extended this possibility to mid-2019 (though with an upper limit of 8000 MWh), which could boost the number of  installations again.

Source: Planenergi

Canada: Solar district heat meets community’s entire space heating demand

2018-06-07T10:30:58+02:00Jan 20th, 2017|

The Canadian Drake Landing Solar Community has hit a new performance milestone, recording its first year of solar-only space heating during heating season 2015-2016. The community’s SDH plant, which has been in operation since 2007, was initially designed to achieve a solar fraction of 92 to 93 % for space heat in an average year. System improvements have increased that share and have made last winter the first time that solar energy was able to meet 100 % of the space heating requirements of the 52 energy-efficient residential buildings.
The families heat their hot water with their own solar water heater and a gas-fired boiler. The initiator of the project was Natural Resources Canada (NRCan), which has since remained the central technical support. “We lowered the district loop temperature to the homes and enhanced the thermal stratification in the tank through reduced flow rates,” Doug McClenahan, Solar Thermal R&D Programme Manager Renewable Heat and Power at NRCan said about the improvements which increased performance over the last five years to an average solar fraction of 96 %. Also important was to include the weather forecast in the operational mode of the system. “In anticipation of a cold front, we fill the short-term storage tank with heat from the borehole seasonal storage at low flow rates over several days, in order to have a heat buffer available with the highest temperature possible while using the least amount of electricity,” McClenahan explained.Initial simulations based on weather data spanning over 50 years showed a 100 % solar fraction year to be a rare event which would only occur in the 34th year of operation. ‘We are now expecting to reach the 100 % milestone relatively regularly,’ said McClenahan.

NRCan also noted in its report about the Drake Landing community that the high performance of solar heating had been achieved with very little electricity consumed, resulting in a coefficient of performance above 30. This means that for every kWh of electricity used by the pumps, the system delivers more than 30 kWh of heat, which is eight to ten times the efficiency of a heat pump. Hence, the technology not only reduces CO2 emissions, but also offers significant opportunities to minimise the plant’s impact on the electricity grid.

More information:

Source: solarthermalworld.org

Switzerland: borehole storage regeneration and solar district heating as solar thermal’s ray of hope

2018-06-11T15:44:13+02:00Jan 10th, 2017|

As 2017 funding for solar heat incentives remains in doubt in several cantons and the priorities of the country´s energy policy haven’t been announced yet, the market outlook for solar thermal has not been very encouraging. But there seems to be a ray of hope in the form of low-temperature collectors for borehole regeneration and solar district heating.

On 24 November, the fifth Solar Heat Switzerland (Solarwärme Schweiz) conference organised by the solar industry association Swissolar, the building services association suissetec and the Federal Office of Energy was held in Lucerne, Switzerland.

The event with 130 attendees took place just a few days before the Swiss referendum on an accelerated nuclear energy exit, which gave the organisers an opportunity to highlight the sun’s role in Switzerland’s energy transformation. ‘As about 10 % of the heating energy in Switzerland comes from electricity, solar thermal can help with replacing nuclear power,’ said David Stickelberger from Swissolar. The strategy assured increased media attention for solar thermal, but interest dwindled soon after the 27 November referendum, when the nuclear energy exit was rejected by Swiss voters.

The political circumstances have cast doubt on the future of solar heat. Half a year ago, cantons Zurich and Zug had announced that they would not be able to finance solar thermal incentives in 2017. And the commitment to Switzerland’s energy strategy 2050 has been put on shaky ground. A vote is scheduled for 21 May 2017, in case opponents of the strategy can gather 50 000 signatures by 19 January next year. ‘As the political situation remains unclear, cantons are postponing their decisions,’ said Stickelberger. According to current planning, the Energy Strategy 2050 is thought to enter into force in 2018. Its aim is to increase the use of renewable energies, including hydropower and energy efficiency. The energy strategy will not permit the construction of new nuclear power plants, but will not limit the lifetime of the existing ones either. The strategy will also lower the CO2 emission limits of vehicles. The most important issue will be additional solar thermal funding from canton governments to incentivise the implementation of energy efficiency measures – including solar heat – in buildings.

Right now, solar heat is coming under fire from two sides: First, there is the cantons’ responsibility for the incentive schemes. The Harmonised Incentive Model (Harmonisiertes Fördermodell, HFM) requires that they all follow the same policy. But given budget restrictions, they have been waiting for the authors of the energy strategy to set priorities before they put aside money for solar thermal incentives. Second, the cantons have to integrate nationwide building energy standards (MuKEn). This means that cantonal law is to stipulate a certain share of renewables that needs to be met when renovating existing building stock. But like the debate about incentives, this one will only be resolved if there is a clear-cut and comprehensive energy strategy in place.

But Stickelberger also pointed to two technologies which give him hope for the future of solar thermal in Switzerland. One is the combination of solar collectors with ground-sourced heat pumps. Pumps which retrieve energy from boreholes are becoming increasingly popular across the country. The city of Zurich in particular set a 2050 target of 450 GWh/year for energy production based on ground-sourced heat pumps as part of its efficiency scenario A from the 2050 energy plan. But experiences and simulations by the Swiss-based SPF – Institute of Solar Technology show that especially in areas with high borehole density, they gradually cool the ground unless an active regeneration method is used to return heat to it in summer.

‘Unglazed solar collectors are one option to regenerate boreholes,’ explained Stickelberger. Other options are PVT collectors, which typically work at low temperatures, or conventional collectors if operated intentionally at around 25 °C. The heat pump itself can also be used for regeneration and the transfer of heat from a building or the surroundings into the ground in summer. At the conference, René Naef from Swiss engineering office naef energietechnik presented the regeneration results of nine borehole locations used to heat three multi-family properties in Mettmenstetten. After one year of operation, the temperature of boreholes using regeneration was 2 K higher than the one of surrounding buildings.

The second technology is district heating. Unlike Denmark, Switzerland has not seen much interest in district heating systems. In the cities, most networks are fed with heat from waste incineration. This type of heat is available all year round at low cost and gives solar feed-in little chance to compete. However, there are also several hundred rural district heating networks, mostly supplied by biomass boilers. At the conference, Michel Haller from the SPF Rapperswil presented a study on the potential of retrofitting these networks with solar thermal technology.
One very attractive project might be the supply of wood- and solar-based heat to the district heating network of the Beznau nuclear power plant in northern Switzerland. It has so far been powered by waste heat from one of the world´s oldest nuclear power stations. Reactor unit 1 dates from 1969 and has been turned off for safety review. After several delays in getting it back onto the grid, doubts are growing whether it will ever be operational again. Unit 2 from 1971 cannot provide enough heat for the entire year, meaning additional boilers are needed. The SPF Rapperswil and the association Wood Energy Switzerland have carried out a study to explore the options available for integrating solar and biomass into the network. “The operators have shown interest in both solar and biomass heat,” said Stickelberger.

This text was written by Eva Augsten, a German freelance journalist specialising in renewable energies.

Websites of institutions and associations mentioned in this article:
Swissolar: www.swissolar.ch
SPF Rapperswil: www.spf.ch
Suissetec: https://www.suissetec.ch/
Wood Energy Switzerland: https://www.holzenergie.ch/home.html
naef energietechnik: http://www.naef-energie.ch/
Swiss Energy Strategy 2050 (in German):

Interview with the region of Styria, SDHp2m project partner

2018-06-11T15:43:55+02:00Nov 4th, 2016|

SDHp2m is a H2020 European Project whose name stands for Solar District Heating (SDH) and actions from Policy to Market. The region of Styria in Austria is one of three EU regions whose regulatory regional authority is a project partner of SDHp2m. Euroheat & Power had the opportunity to interview one of the representatives from the Provincial Government of Styria, Mr. Dieter Preiß, about the experience of this region so far as a project partner.

Read the interview here.

Webinar on ‘Renewable district heating – small local grids and cooperative utilities’

2020-04-01T16:37:35+02:00Nov 2nd, 2016|

District heating based on local renewable energy sources is becoming more and more an appealing solution for small communities in search of energy independence and of a stable price for their thermal energy supply. Such solutions often foresee a strong and direct involvement of the customers who could even own, at the same time, their heating grid by constituting a cooperative company to run the business.

Examples from Denmark and Germany of such district heating approaches with exciting and inspiring stories to show how consumers can take the lead in the transition towards a clean and sustainable future were presented at the ISES webinar on 26th October 2016.
www.youtube.com/ISES webinar

New video on smart heating systems

2018-05-17T11:25:45+02:00Oct 27th, 2016|


The Danish 4DH Research Center published a new video on 4th generation district heating technologies. So called ‘smart heating systems’ are necessary to lower our CO2 emissions and achieve 100% renewable energy.
Today, 40% of the energy consumed in Europe is for heating. All this energy can become sustainable through modern district heating systems collecting waste heat from power plants and industry, and working at low temperatures which minimizes the heat loss and integrates more sources of renewable energy. The video below describes how Europe could transform its heating supply to be low-carbon and cost-effective whilst maintaining security of supply.Source and further information about 4DH and the video: www.4dh.dk

France: Is this the new solar district heating country?

2020-04-01T16:30:46+02:00Oct 26th, 2016|


After France had become involved in a couple of EU-supported projects as a newcomer, the country is now ready for take-off in the solar district heating (SDH) market. Monitoring data from the first two French pilot plants show performance to be quite good and the systems to be highly reliable.
The chart depicting the performance of the 458 m2 evacuated tube collector field in Balma-Gramont was presented by Fabrice Renaud, Research Engineer in the R&D centre Cylergie at the French group Engie, during the 4th International Solar District Heating Conference in Billund, Denmark. There is also a new strategy document being devised to advance the development of SDH in the French region of Auvergne – Rhône-Alpes.Chart: Engie Group

Renaud emphasised the satisfactory results in specific solar yield of between 550 and 560 kWh/m2 from the plant in Balma-Gramont, near Toulouse in southern France. The solar fraction, however, dropped from almost 6 % to 4.5 % because of an increased demand in the district heating network. The solar plant demonstrated a high degree of reliability and did not cause any major problems (stagnation never occurred). Even so, it would be advantageous to improve the system and reduce the power consumption of auxiliary components, something that is still too high (about 17 kWh per MWh of generated heat).

Renaud also presented the monitoring outcomes of the 300 m2 flat plate collector SDH plant in Juvignac in southern France. Although the annual solar yield matches up with design values (about 720 kWh/m2), the solar fraction is below expectations (about 4 % instead of 5,5 %) – again, because of higher demand from power consumers. This plant did experience some stagnation because of interruptions in the DH network: One option to avoid this problem in the future would be to include a tank for storing additional solar heat.

A national survey carried out by the Regional Energy and Environment Agency of Auvergne – Rhône-Alpes (RAEE) found that 800 DHC systems were in operation countrywide, with around 15 % of the district heating demand being covered by renewable energy sources and 25 % by waste heat, at an average cost of heat of 70 EUR/MWh. The number of SDH installations was said to be three existing ones and two under construction. The SDH collector area expected to be installed by 2030 was 800 000 m², plus an increase by a factor of 5 in the use of RES in district heating (from 0,7 MTOE to 3,4).

Beyond the pilot plants and their crucial role as ‘technology showrooms’, there should also be proper policies in place to promote SDH and in many cases the best place to do this is at regional level. In the framework of Horizon 2020 project SDHp2m…from policy to market, the French region of Auvergne – Rhône-Alpes is currently drafting a strategy document to develop SDH locally in cooperation with RAEE, the National Solar Energy Institute (INES) and CEA Tech.

RAEE’s starting point was a SWOT analysis – which is short for Strengths, Weaknesses, Opportunities and Threats. The results highlighted the typical strengths of solar thermal – being a freely available resource and a no-emission ‘fuel’ – as well as its opportunities, in line with current developments in the district heating sector, such as in low-temperature systems, long-term storage, energy efficiency, etc. ‘Regarding drawbacks, we looked at the space requirements as the main weakness and at building heat regulations, which have not been yet extended to include SDH contribution,’ RAEE’s Mathieu Eberhardt said. Finally, the main threat to widespread market deployment was the competition among many different thermal energy sources: other renewables, cheap waste heat and fossil fuels, especially natural gas.

In order to develop a joint strategy, the region set up a stakeholder group by organising a kick-off meeting in May 2016. Many of the 22 people attending the meeting came from different backgrounds: associations or stakeholders from the DH and solar industry, policy makers, DH operators and planners, energy cooperatives and initiatives, urban planners and heat planning experts, financing institutions and national agencies.

The discussions during this meeting led to the identification of several stakeholder suggestions:
•    Develop common list of arguments to convince local authorities in region that SDH is relevant
•    Include solar thermal more effectively in strategic planning
•    Develop tailored communication packages to reach citizens
•    Develop or disseminate simple tools to professionals to facilitate SDH feasibility studies
•    Utilise the opportunity of case studies planned as part of SDHp2m
•    Increase awareness of technology prices (and ROI) in France compared to other solutions with low fossil fuel prices.

Eberhardt said that the stakeholder group was going to meet again in November 2016 in order to present a final version of the initial national survey on SDH and the regional action plan. Beyond that, another relevant event will take place in the region in February 2017: the SDH conference in Clermont-Ferrand. At national level, there is a district heating conference organised by French district heating association AMORCE and scheduled in Paris for 6/7 December 2016.

Riccardo Battisti

Solar district heating: Good performances all over Europe

2018-06-11T15:42:56+02:00Oct 19th, 2016|

The 4th International Solar District Heating (SDH) Conference, which had been organised under the auspices of Horizon 2020 project SDHp2m…from policy to market on 21/22 September 2016 in Denmark, showed the importance of analysing real-life monitoring data from European SDH plants, with one conference session dedicated exclusively to the topic.

These kinds of comparisons enable an understanding of the actual performance of such large collector fields and offer an opportunity for optimising power output and for creating best-practice examples of new plants. For example, the chart displays ten years’ worth of monitoring data from the German plant in Crailsheim, which has met solar yield expectations.

Roman Marx from the German Institute of Thermodynamics and Thermal Engineering (ITW) of the University of Stuttgart, said that the average annual solar yield was 2,631 MWh (360 kWh/m2* a), compared to a previous estimate of 2,575 MWh. The solar fraction, however, reached a share of slightly above 40 %, below the expected 50 %. The reason for this lower-than-expected value was a higher total heat demand in the initial estimate, but also a lower usable capacity for seasonal storage, with the maximum storage temperature having been reduced from 80 to 70 °C. The owner of the plant is now considering a partial replacement of the 12-year old solar collectors by more efficient panels.
Monitoring data for the specific yield of 13 Austrian large-scale solar plants depending on feed and return line temperatures
source: SDH conference presentation from AEE Intec

The district heating session also included a report by Samuel Knabl from Austrian research institute AEE INTEC on the monitoring results of 30 of the country’s SDH plants, which had been supported by the national subsidy scheme for large-scale systems. The majority of the 14 systems which completed the monitoring phase almost achieved their expected solar yields; only two installations deviated significantly in their results. Knabl emphasised the fact that the return temperature of the district heating grid had a significant impact on collector field efficiency, as the above chart shows: specific collector yields ranged from 240 to 520 kWh/m2a.

Promising results came in from the biomass-fired district heating plant in Mallnitz, where in summer the peak load operation hours of the oil-fired boiler as well as the operation time of the biomass boilers was significantly reduced. Another example is the suburb of Salzburg-Lehen, where a 2,048 m2 collector field heats around 38,000 m2 of floor area in flats, a youth hostel, office buildings, a hotel and 150 renovated homes. The solar fraction is 29 %, of which 12 % are directly used in the buildings and 17 % originate from indirect use by the heat pumps, which have a seasonal performance factor of 4.5.

Plant Marstal Dronninglund Braedstrup
Collector field 33 000 m2 37 600 m2 18 600 m2
Seasonal storage 75 000 m3 PTES 60 000 m3 PTES 19 000 m3 BTES
Short-term storage 2 100 m3 7 500 m3
Heat demand 32 000 MWh/a 40 000 MWh/a 45 000 MWh/a
Solar fraction 41 % 41 % 23 %
Specific yield of solar field 395 kWh/m2a 447 kWh/m2a 432 kWh/m2a
Seasonal storage efficiency 62 % (20 to 84 °C) 90 % (10 to 89 °C) 102 % (11 to 49 °C)*
Storage heat capacity (temperature difference) 5460 MWh (64 K) 5,500 MWh (64 K) 400 MWh (38 K)
No. of storage cycles 1 2.2 0.5

Primary technical and performance figures based on 2015 data from three Danish large-scale SDH plants. *102 % of storage efficiency has only been possible because the system used a certain amount of heat from the previous year. BTES is short for Borehole Thermal Energy Storage; PTES is Pit Thermal Energy Storage
Source: SDH conference presentation from Solites

The presentation by Thomas Schmidt from German research institute Solites confirmed the often-quoted average annual yield of 400 to 450 kWh/m2 for large-scale collector fields in Denmark. Schmidt went through the monitoring data provided by the operators of the three SDH systems in Marstal, Dronninglund and Braedstrup (see the table above). The difference in yield (between 395 and 447 kWh/m2a) was mainly a result of older collectors still being in operation, Schmidt explained. Whereas the 37,600 m2 in Dronninglund were installed in 2014, more than half of the 33,000 m2 in Marstal had been installed before 2004, while 15,000 m2 were added in 2012. In Braedstrup, 8,000 m2 of collectors were inaugurated in 2007.

In addition, the Solites researcher analysed the relationship between heat taken from the storage tank and the tank storage capacity, which leads to the number of storage cycles. A ratio of 1 is achieved when – as in the Marstal case – a large part of the heat is fed directly into the district heating network. In Dronninglund, the mode of operation is that almost all solar energy is transferred to the grid through the seasonal storage tank, drawing more than twice the energy capacity of the pit storage over a year. System efficiency also depends on these different modes of operation because it includes the losses compared to heat utilisation by tank.

Braedstrup cannot be directly compared to the two other installations. Its pilot-phase borehole storage offers a much lower heat capacity (400 MWh) and maximum temperature (about 49 °C). Still, the monitored solar share of 23 % is higher than the 18 % that the system was expected to have. An extension of the seasonal storage is in preparation.

More information:
Gram district heating
Institute of Thermodynamics and Thermal Engineering
Steinbeis Research Institute Solites

Riccardo Battisti

1 Million Square Meters Solar Thermal Collectors in Danish District Heating Plants

2018-06-11T15:42:37+02:00Sep 28th, 2016|

Right on time for the opening of the 4th International Solar District Heating Conference in Billund, the host country Denmark reached a magical barrier: more than one Million square meters solar collectors are now installed there. The Danish District Heating Association counted exactly 1 003 024 square meters at the beginning of the Conference on Wednesday, 21st September, in a total of 85 district heating networks supported by solar thermal energy.

180 international experts from 20 countries – also this is a record number – have met for the 4th International Solar District Heating Conference in order to benefit from the experience of this leading country. They were not only impressed by the top-class presentations and technical tours to some of the world largest solar collector plants, but could also admire a reduced-scale model of such a plant in Legoland Billund, where the Conference took place. This solar collector plant made in Lego bricks represents the plant from Braedstrup, with which the world-wide unique boom of the Danish XXL solar thermal plants began, approximately ten years ago.Large-scale solar thermal plants can compete today with all forms of fossil fuels. The sector reaches heat prices from 3 to 5 cents pro kWh, provided that the plant is large enough. And they are always getting larger: in Silkeborg in Central Denmark the new record plant is currently under construction with 156 000 m² and a nominal power of 110 Megawatt. But the world’s market leader Denmark is not the only country in which solar thermal plants in such dimensions are developing. In the Austrian city of Graz, plans are being made for a plant of even more impressive dimensions: 450 000 m² solar thermal collectors should supply the district heating network of the second largest city of the Alpine Republic to cover 20% of the heat demand.

Also political spheres have become aware of the importance of renewable district heating all around Europe. “District Heating and Cooling are now an important topic in Brussels to push renewable energies and efficiency technologies.” said Paul Voss, director of the European District Heating Association Euroheat & Power. Unlike in some earlier papers from the EU, they play an important role in the recently published Heating and Cooling Strategy until 2030. This also appears in the most recent budget planning for EU subsidy programs.

For the organizers of the 4th International Solar District Heating Conference, the Danish District Heating Association, the engineering office PlanEnergi and the German Steinbeis Research Institute Solites, the economical feasibility is currently not the main reason why the development of renewable district heating networks in Europe and the world is still so uneven. There are several well made subsidy programs at national level, in Germany, Italy, France and Austria, reports Thomas Pauschinger from Solites. Outside of Denmark, the possibility of using solar heat for district heating networks is simply still not enough known. One of the barriers is administrative obstacles like finding and getting permission for adapted locations for building large collector fields. Pauschinger: “At the local level, there are three main problems: areas, areas and areas.”

This is not the case in Denmark, where the collector fields are mostly located in agricultural areas at the city’s borders. The solar thermal networks are mostly organized in cooperatives and realized without subsidies, thanks to the high taxes on fossil fuels, among other things. In Jelling, the local operator of the plant reported that the heat price for customers has decreased as a consequence of the installation of 15 000 m² solar collectors. This is the case in several other locations in Denmark. Jelling was, together with the recently extended 44 800 m² solar thermal plant of the City of Gram, aim of a technical tour in the framework of the international congress. Gram is currently the district heating network with the highest solar fraction. More than 50% of the yearly heat demand is covered by the sun. This is enabled by a pit thermal energy storage in which 122 000 m³ water are being heated up to 90°C during the summer.

If the experts who travelled to Billund are of course interested in such constantly increasing records, they also come to exchange on technical details and share experiences from colleagues from other countries, research institutes and companies which are being discussed really openly in this circle.  The main topics are here longevity, energy efficiency and a reliable operation of such plants, said Pauschinger: „These details are the decisive factors for continuously reducing the costs of harvesting solar energy.”

The next opportunity for such a large and intensive exchange will arise in 2018 for the next edition of the conference in Austria.

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