Fraunhofer-Gesellschaft
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Lisa Neusel und Prof. Clemens Rohde vom Fraunhofer ISI
© Fraunhofer / Jonas Ratermann

Power is expensive; more expensive than ever. Our efforts at accomplishing energy transition so far have been half-hearted at best – now we have to pick up the pace. But how?

© Foto: Fraunhofer / Jonas Ratermann

Our energy

Webspecial Fraunhofer magazine 3.2022

Let there be… energy!

It was September 15th − in the last few days before the calendar turned to fall, Germans were basking in the mild temperatures of late summer, with 17 degrees in Berlin and 23 in Munich. Then suddenly, a chilling fear spread over Germany, as the Deutscher Städte- und Gemeindebund e. V. (German association of towns and municipalities) warned of widespread power outages. “There is a danger of blackouts,” confirms Gerd Landsberg, the association’s managing director. His concern stems primarily from the 650,000 fan heaters that consumers have purchased this year, fearing a cold winter and extremely high heating costs. Emergency tips are going around like wildfire: camping stoves for hot meals, battery-powered radios, candles and flashlights. Russia’s war of aggression against Ukraine has brought about a host of new developments to Germany − but Germans are determined to develop themselves even further, and quickly. 
 

How can we prevent major power supply faults? In the joint project “Netzregelung 2.0” (grid control), researchers at the Fraunhofer Institute for Energy Economics and Energy System Technology IEE have set out to answer this question, in collaboration with partners such as TU Braunschweig, the University of Kassel and Germany’s four transmission system operators, as well as power converter manufacturers and the Network Technology/ Network Operation Forum at VDE. In addition to various other studies, the team created a worst-case scenario based on a real event: On November 4, 2006, a chain reaction caused by a switching operation in the transmission system split the combined central European grid split into three parts. The researchers simulated the events of the fault, but under even more challenging conditions. In their simulation, the grid had to transport far more power. Dr. Philipp Strauß, deputy director of Fraunhofer IEE, explains the problem the team had to work on: “Conventional power plants have large rotating generators which store mechanical inertia. If a fault occurs or a power plant is shut down unexpectedly, this rotating mass continues to move for some time afterward, as it cannot simply stop all at once. This is then reflected by electrical inertia in the grid, which compensates for faults.” At present, renewable energy generators are mostly connected to the grid via power converters, which do not provide any inertia. The converters are supposed to adjust the energy that they feed into the grid to its existing voltage and frequency − for example, at a photovoltaic solar plant, the converter will change the direct current the plant generates into the alternating current that most grids use. Now, Fraunhofer researchers are working on a digital control system for converters that will ensure they operate in a similar way to rotating generators in the future. This involves setting up the power converter in such a way that if the current fluctuates, the converter continues to function as normal for a period of time afterward, thus activating the instantaneous reserves, which then stabilize the grid. 

“We wanted to find ways of controlling these power converters within an integrated grid system. Is there any way they could be used to absorb major grid faults?” asks Dr. Strauß, who is coordinating the entire project at Fraunhofer IEE. Can the technology fulfill the researchers’ hopes and do enough to stabi-lize Germany’s power grids? “The answer to that question is an unequivocal ‘yes.’ With the right control system, you could actually have grids that only use converters; even in the worst-case scenario, they would do enough,” reports the researcher. The new control system can even coexist with the current systems − and this will be an important point if renewable energy is to replace fossil power plants on a step-by-step basis. The researchers have even designed the necessary control procedure for current stabilizat ion. These grid-forming power converters with digital electrical inertia are already required in maximum-voltage applications and large-scale power converters in the transmission system. However, although plans are in place to integrate converters into the distributed grid as well, this will require further research. One tricky issue here is how the converters interact with existing protective technology − the last thing the researchers want is for the new power converters to create new problems.

Dr. Philipp Strauß, Fraunhofer IEE
© Fraunhofer / Jonas Ratermann
“The answer to that question is an unequivocal ‘yes.’ With the right control system, you could actually have grids that only use converters; even in the worst-case scenario, they would do enough.” Dr. Philipp Strauß, Fraunhofer IEE

The energy transition cannot happen without the digital transformation

Ensuring grid stability is no mean feat – but the digital transformation is capable of much more. In many quarters, it’s seen as the key to achieving the energy transition, reducing our dependency on fossil fuels and alleviating the worst effects of the climate catastrophe. “The digital transformation has picked up speed significantly at the various grid levels, particularly in maximum- and high-voltage grids,” reveals Dr. Marijke Welisch, managing director of the Fraunhofer Cluster of Excellence Integrated Energy Systems CINES. “But with all the discussions around price increases and gas supply problems, the issue has been relegated to the background. And that’s disastrous. After all, practically every aspect of the energy system transformation relies on digital technology – without extensive digitalization, the energy transition cannot be achieved in time.” One of the reasons for this is that the energy system is becoming very compartmentalized, due to the proliferation of photovoltaic plants, heat pumps and electric vehicles, etc. However, the grids cannot simply be expanded at random. Likewise, as it now consists of millions of plants instead of a few very large power stations as in times gone by, it would be almost impossible to control the system without digital intelligence to monitor the external influencing factors and divide up the signals. The time needed for the energy transition is another sticking point. Many processes can only run quickly and efficiently if they are run by digital means. “There is a great deal of new equipment and network components in need of approval. However, if the approval applications end up on the relevant official’s desk as a fax, that’s not effective, and it’s not appropriate for the times we live in. The digital transformation absolutely has to happen here too,” comments Manuel Wickert, head of the cluster’s research team for digital transformation.

Dr. Marijke Welisch, Fraunhofer Cluster of Excellence Integrated Energy Systems CINES.
© Fraunhofer / Jonas Ratermann
“With this study, we hope to spark discussions within the political sphere about the importance of the digital transformation for the energy transition.” Dr. Marijke Welisch, Fraunhofer Cluster of Excellence Integrated Energy Systems CINES.

In “Digital Transformation of the Energy System – 14 Theses for Success,” a study published at the end of September 2022, the researchers in the cluster outlined a number of theses on the subject; each one is accompanied by a summary of the key facts for policymakers and specific recommendations for action for the energy sector. “We started by analyzing project scenarios: What might a completely digitalized energy system look like in five years time? What about a completely analog one? Or a system that maintains the status quo? Using these scenarios as a basis, we combined trends from the energy sector and the digital transformation, and looked for areas of overlap,” explains Dr. Welisch. This process allowed the researchers to identify five key focus areas: data economy, energy systems integration, power plant communications, cybersecurity and grid operation and planning. When it comes to the data economy, it is essential for grid operators to have sufficient data for power trading and planning related system services, such as instantaneous reserves. Because after all, uncertainty increases the costs of compensation. This is why the first thesis states that in the future, energy’s value will be dependent on the data associated with it. This is best explained using an example: There was a solar eclipse on March 20, 2015 and it was not clear how this natural phenomenon would affect the generation of solar power – as such, compensating current was provided at very high prices. The more meteorological and photovoltaic data available, the more effectively and cheaply these kind of events can be managed. “This is why we should not just be relying on smart meters as an efficient data source; we should also take plant manufacturers’ cloud systems into consideration,” the researchers add. The scientists also advocate for cybersecurity reforms. In the study, they suggested that rather than trying to protect every energy system without exception, it would be better to change our attitudes at a fundamental level. Instead of attempting to achieve an all-encompassing defense, we must try and design systems that can handle possible faults, attacks and outages more effectively – and maintain operation of critical processes even in difficult situations. “With this study, we hope to spark discussions within the political sphere about the importance of the digital transformation for the energy transition,” concludes Dr. Welisch. And this might just give Germany’s energy transition the push it needs. 

In fact, Germany’s energy market is in ever more urgent need of fresh ideas to increase its resilience against the impact of international political developments – and to stem the tide of climate change too, of course. For some people, looking back on Germany’s dependence on gas pipelines brings to mind the image of a patient hooked up to an IV. The Fraunhofer Institute for Solar Energy Systems ISE’s Energy-Charts platform offers an overview of this “medical history.” The platform, which is freely available online and updated hourly, offers important data and interactive graphics on topics like electricity production and stock exchange prices – meaning that it plays an important role in keeping discussions around the energy transition transparent and factual. “We use data from ten providers, including the EEX energy exchange in Leipzig, where all transmission system operators report their data and the equivalent association for European transmission system operators, ENTSO-E,” explains Prof. Bruno Burger, who created the Energy-Charts at Fraunhofer ISE. The graphics reveal various patterns: For example, the charts tracking the annual expansion and contraction of Germany’s net installed solar capacity show clear dips corresponding to the policies of particular energy minsters – the “Altmaier drop” and the “Gabriel trough,” as the researcher calls them. While an additional 7.91 gigawatts of net capacity was installed in Germany in 2011, only 3.7 gigawatts were added in 2013. Then in 2014, that number fell to 1.19 gigawatts. In addition to illustrating the changes in power and gas prices, the charts also allow viewers to see the share of renewable energy in the energy mix, trends in power consumption, weekly and yearly power supply volumes and the typical daily development of power generation and consumption figures.

For the electricity prices, the researchers not only analyze data from the past and present, but also make projections for the future. Unfortunately, these predictions provide little in the way of hope. In December 2022, the price of power is expected to reach 51 cent per kilowatt hour; by the first quarter of 2023, it is set to jump to 68 cent. Even by the first quarter of 2024, the prices are likely to be at a level of 43 cent – so no relief in sight. “We warned previous German governments over and over that if nuclear energy and coal are phased out, we would need renewable energy to compensate. But Russian gas was cheap. Now it will take us until at least 2030 to really get back on course – the current government cannot put this situation right in one legislative period,” says the researcher. 

 

Prof. Bruno Burger, Fraunhofer ISE
© Fraunhofer / Jonas Ratermann
“Russian gas was cheap. Now it will take us until at least 2030 to really get back on course.” Prof. Bruno Burger, Fraunhofer ISE

Smart coatings keep the heat in or out depending on the season 

Energy savings don’t have to come at an exorbitant price, especially given the new opportunities that new technologies are creating here – take smart windows, for example. They can reduce the need for air conditioning by blocking the sun’s thermal radiation in summer and then reduce the need for heating in winter by letting the sun’s warmth in. These thermo- or electrochromic coatings can reduce a building’s cooling and heating energy requirement by anything between 10 to 60 percent, in extreme cases. Researchers at the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP are working with partners to develop the basis for these coatings. “In the EU project Switch2Save, we and our partners at the University of West Bohemia in Pilzeň succeeded in manufacturing thermochromic vanadium dioxide coatings on ultra-thin glass at pilot scale using the roll-to-roll process,” reports Dr. Cindy Steiner, group manager at Fraunhofer FEP.“This achievement is an important step on the road to scaling this technology!”

The Fraunhofer Cluster of Excellence Programmable Materials CPM have made a similar breakthrough with programmable insulation for building facades, enabling the outer casing of a house to react to the external temperature. This insulation is based on a foam that changes its form depending on the temperature. At high temperatures, its pores open and expand; then at night, it becomes compressed, allowing fresh air to circulate through openings in the rear-ventilated facade. During the manufacturing process, the producers can determine how the foam will change its form and at what temperatures. What makes this foam so special is that the process is reversible, meaning the foam can keep re-opening and closing its pores. “This kind of insulation makes a massive difference for cooling especially, where it can save up to 40 percent of the energy,” says Dr. Susanne Lehmann-Brauns, who heads up a group devoted to these programmable materials at Fraunhofer CPM.

However, energy saving measures by companies have a greater impact than those in private households. The latter accounts for only 26 percent of Germany’s power consumption, while industry makes up 44 percent. For those looking for possible ways of saving energy in the industry sector, the Fraunhofer Institute for Systems and Innovation Research ISI is there to lend a helping hand. Since 2009, the ISI’s researchers have been conducting the preparatory work that allows for quick implementation of solutions today. “We already set up 30 pilot networks more than 13 years ago. They generally consist of 8 to 15 companies and a technical energy consultant that link up for a period of 2 to 3 years with the goal of implementing energy efficiency measures in areas like heating and cooling, lighting, air compression, process optimization and operational workflows, so as to reach a specific energy saving target,” explains Lisa Neusel, a research fellow at Fraunhofer ISI. The foundation of this initiative is a network management model developed during the pilot phase of Fraunhofer ISI’s “Lernende EnergieEffizienz-Netzwerke” (learning energy efficiency networks) project: This uniform standard makes it possible compare the networks’ energy saving successes in a scientific manner. The tool the researchers developed for the model records various details, such as the amount of CO2 saved by a particular measure, the category the measure belongs to and how much it cost. The companies also engage in a moderated discussions, which is a vital factor for the networks’ success. “Regular peer-to-peer discussions help the businesses involved to quickly learn where they can save energy,” Ms. Neusel points out.

The German federal government was quick to adopt this impressive network model: In 2014, it joined forces with 22 industry associations and organizations to create the “Initiative Energieeffizienz- und Klimaschutz-Netzwerke” (energy efficiency and climate protection networks initiative). The initiative now comprises 346 networks and over 3,000 companies. Since 2014, the process of implementing the steps proposed in the initiative has been supported by annual voluntary monitoring conducted by Fraunhofer ISI and the adelphi research and consultation institute.

Now, finding ways to save energy quickly is a more topical subject than ever in the initiative. The networks help the companies to reduce their energy consumption and mitigate the effects of energy price increases within the space of four weeks, through practical, low-investment measures that can be implemented in the short term. “The best option here is a change in the way a company consumes energy, i.e., measures that can be adopted without any large investments,” explains Prof. Clemens Rohde, a business unit head at Fraunhofer ISI. Prof. Rohde estimates that depending on the company, short-term measures can achieve savings of around 5 percent. “However, in the medium term,” the professor continues, “companies must take a strategic approach to this issue. We have been wondering how to get companies to consider the question of energy efficiency at board level for quite some time. Now, unfortunately, Putin has done it for us. Energy has gone from a typical secondary issue languishing in a corner to a strategic priority.”

Saving energy is important. However, using the energy we generate in the most consistent way possible may be even more important, as consistent energy use brings a double advantage. Not only does it have a positive effect on companies’ balance sheets, but it also improves grid stability. And that’s a big plus, because although fluctuations don’t do the power grid any favors, they are an inherent part of wind and solar energy. Making our energy requirements more flexible could be at least a partial solution here. 

However, this will require incentives, such as energy balancing markets, for example. These markets are attractive for large-scale energy consumers such as aluminum or paper manufacturers, because they can save a great deal of money if they bring their systems on- and offline in accordance the grid’s needs – which will also stabilize the electricity grid. However, to do this, companies need to know what opportunities for energy flexibility their business offers, and grid operators and companies must communicate with each other. Luckily, researchers at the Fraunhofer Institute for Manufacturing Engineering and Automation IPA and their partners in the project SynErgie have developed an energy synchronization platform that can make this happen. “The platform is divided into two subplatforms, one for production companies and the other for offering and procuring market services,” explains Can Kaymakci, a Fraunhofer IPA scientist. The company version shows businesses the various measures they can adopt to make their energy requirements more flexible. It analyzes data from companies’ machinery, identifies areas that offer dynamic energy flexibility in production processes and infrastructure, and shares this information in a standardized way. While these processes can be fully automated, most companies prefer to have a human as the final decision-making authority. Options for creating energy flexibility include delaying production start times and adapting machinery layout plans and working hours. 

Can Kaymakci, Fraunhofer IPA.
© Fraunhofer / Jonas Ratermann
Can Kaymakci of Fraunhofer IPA has developed a platform for smart energy flexibility management in the project SynErgie.

It is also possible to implement technical measures for improving energy flexibility, such as switching energy carriers or taking advantage of processes’ inherent energy storage capacity.  Other opportunities lie in the control systems for company infrastructure, for example, the air compression and air conditioning systems. “Cooling and heat generation are a particularly promising areas of potential. For example, depending on energy prices, a furnace can run on gas and/ or hydrogen, or electricity; you can even switch from one source to another during operation,” explains Mr. Kaymakci. To take another example, if there is an oversupply of electricity, the furnace can be set to full power and heated to a higher temperature for a short period, and then draw from this higher temperature when electricity prices increase later on. The platform already offers integrated services for optimizing this kind of load curve. “The services’ central database and functionalities are standardized; however, there are different services for each process, which are also adapted to suit the specific company,” Mr. Kaymakci points out.

The researchers also described the market side of the platform. “The companies can use the market platform to find various services that will help them commercialize their energy flexibility,” Mr. Kaymakci continues. The platform cannot be used to conduct transactions or exchange data or energy – it is intended to function more like a kind of business directory. Because even large companies are not active on the energy market themselves; they leave this to marketers and aggregators that combine the energy flexibility of multiple businesses into a “virtual power plant” and make it available on the energy market. Essentially, the market platform makes it easy for companies and marketers to find each other. 

 

Boosting industrial energy saving potential through targeted incentives 

But how effective is this kind of solution? “With the industries and sectors in our consortium alone, we could reduce the energy grid load by 10.7 gigawatts for 15 minutes, or increase it by 9 gigawatts. That means we have a total potential of 19.7 gigawatts – which is equivalent to 5,620 onshore wind farms or 540 of the largest photovoltaic plants in Germany. So, our system can drastically increase grid stability”, says Mr. Kaymakci. All the boxes have been checked from a technical perspective – now it’s a question of unleashing this potential. And that calls for regulatory incentives. The Fraunhofer IPA researchers are playing their part here too. When Dr Robert Habeck, Germany’s Federal Minister for Economic Affairs and Climate Action, brought the energy market back into the spotlight, the IPA team produced a paper to serve as a guide on the topic; now, with the third amendment to the Energy Security Act (Energiesicherungsgesetz, EnSiG), the researchers’ efforts to drive regulatory change are bearing fruit. 

This basic principle of flexibility and networking also works at a smaller scale, making it possible to achieve new levels of security even in difficult times. For example, there is great potential to be unleashed in the area of electric vehicles, as not only can they store energy for themselves, but they can also compensate for grid fluctuations by acting as storage batteries. That presents an advantage for both grid operators and the users of e-vehicles. In a one-year trial run in Denmark, users earned 1,300 euros on average from feeding power into the energy network on a counter-cyclical basis. However, many e-car owners would be unable to benefit from this type of system, because they would need a vehicle with bidirectional charging, and the first models are only coming on the market now. “In order for electric vehicles to be integrated into an intelligent power grid, the network operators would need to know how many cars they can charge up or draw from, at what times and to what extent,” explains Oliver Warweg, a group manager at the Advanced System Technology (AST) branch of Fraunhofer IOSB. “If they have to control each vehicle separately, the costs will be enormous.” And these costs do not yet reflect the current value. That’s why Fraunhofer researchers are working in a variety of different projects that aim to make the process less costly by enabling grouped communications with the vehicles.

In one such project, Shared Area Charging, the scientists plan to equip a parking lot with 40 charging stations and treat it as a virtual storage facility. In the long term, many of these virtual storage facilities could be merged, allowing the energy suppliers to communicate with them as one group. The key ingredient here is an app where vehicle owners can specify the charging level their cars need. The researchers at Fraunhofer IOSB-AST are using the information from the app to operate the system and develop the algorithms needed to combine large numbers of vehicles into one entity. “For example, we need projection models for planning which cars would be available at what times and how much storage capacity they have. We are also working on integrating the flexibility this would create into our market offering, i.e., dividing up the theoretical flexibility shown in our calculations and assigning it to individual vehicles that are actually available.” An initial pilot project is running in a neighborhood of the city of Suhl in Thuringia and plans are in place to conduct a larger pilot in Erfurt. The team are also working to create a shared area charging model for an entire city district. Rather than taking place under controlled lab conditions, this project is being carried out in the real world – and now, the researchers’ vision is gradually coming to life. 

 

A ‘self-aware’ energy system? 

That’s not the only dream now becoming a reality, as climate activists’ hopes of seeing a rise in the share of solar energy are also coming true. Many people are installing rooftop photovoltaic systems on their houses in preparation for winter — in fact, almost every module on the market has been bought up. However, with every new set of solar cells and every new electric car connected to the grid as a power storage unit, the energy system becomes more decentralized and complex. And that means it is also much harder to manage. “It’s not as easy to match up generation and consumption as it used to be,” confirms André Baier, a project manager at Fraunhofer IEE. “What we really need now is a high degree of automation, including artificial intelligence, so that in future, we will be able to coordinate complex processes with each other in real time.” The Bundesverband für Energie und Wasserwirtschaft BDEW (German federal association for the energy and water sectors) is clearly thinking along the same lines, as it hopes to make the energy sector a leading market for artificial intelligence. And that is an important goal for Fraunhofer IEE as well. 

That is why the institute is bringing its expertise to bear in various related research initiatives, such as IC4CES, alongside other stakeholders from research, industry, society and politics. Their mission is to give the energy system an “awareness” of the state of its systems, so that it can control them autonomously in the future. “We hope to use artificial intelligence to create cognitive energy systems that will make an energy supply based on renewable energy possible, secure and affordable,” says Mr. Baier. The researchers are focusing on three key areas here: The first key area is cognitive energy grids, namely a grid that has the ability to guarantee energy security even in increasingly complex situations. The ideal outcome of this research is to achieve security of supply without increasing the cost of the entire energy system. The second key area is cognitive energy system technology, which covers everything that is connected to the grid, from inverters to the photovoltaic systems themselves and the energy consumers. The last factor is the cognitive energy sector, meaning the problem of how to bring this fluctuating, decentralized energy to the market. Here, the researchers are investigating what kind of new business models would be needed, for example, to account for the interactions between consumers or producers and public utility companies. 

To demonstrate the potential of artificial intelligence, the researchers turned to the example of energy trading, specifically wind energy. “We were able to show that artificial intelligence can automatically make any energy that is generated available on the market, and achieve results that are just as good as human sellers, or even better in some cases,” affirms Mr. Baier. The research team is using a variety of artificial intelligence approaches here, such as supervised learning, whereby the system makes decisions based on a controlled data set that is used to train it. This is a good fit for applications such as predicting wind and solar energy generation. By contrast, in reinforcement learning, the system runs in a strictly controlled environment, such as a group of power supply lines with a specific operating load. If one line breaks down, the system will detect this and attempt to find the best way of distributing the corresponding quantity of energy across the other lines. If this is not possible, the system must then disconnect individual lines or reduce the amount of power coming from them – which can also be accomplished using AI-driven approaches. Although artificial intelligence is already fit for use in prediction applications, more research is needed in the field of automated grid control. This is because the AI solutions that exist currently are still black box systems – meaning the researchers do not know how AI engines come to the decisions they make. However, Fraunhofer and the University of Kassel plan to change this over the coming years. Awareness is on the rise everywhere; our awareness of energy, and the energy system’s awareness of itself.

Further information

© Fraunhofer / Jonas Ratermann

Make some room! Finding space for solar modules and wind turbines

Germany has set itself some ambitious  energy transition targets, and  solar and wind power are the cornerstones  of its strategy. For solar energy,  the country has stated that it aims  to expand its capacity to a 400 gigawatt  peak by 2040. That raises a number  of questions: For one thing, will  we have enough space for all the photovoltaic  modules we need? If yes,  where will we put them? And how  can we find room for them with as little  conflict and as much public support  as possible? 

“We will have  enough space,” asserts Dr. Harry  Wirth, head of the Photovoltaic Modules  and Power Plants section at the  Fraunhofer Institute for Solar Energy  Systems ISE. “And it’s all thanks to integrated  photovoltaics. And that’s  not all they can do. Integrated photovoltaics  have the potential to create  useful synergies in a wide range of  applications.” For example, in agriculture,  the modules can be mounted on  stands over the fields, where they will  give crops a certain amount of shade  and protect them from extreme  weather events. The researchers are  using simulations to determine how  much light would come through, how  various types of plant would fare under  the modules and how the photovoltaic  systems would affect harvests. 

Scientists are also investigating the  possibility of floating photovoltaics.  In addition to protecting quarry  ponds and artificial lakes from overheating  and excessive evaporation,  the modules could reduce wave action,  which would reduce the erosion  of the shorelines. Building facades also  have plenty of room to spare, but  as yet they have only rarely been used  for generating solar power. However, with Fraunhofer ISE’s MorphoColor®  coating, solar modules will no longer  be a threat to architectural aesthetics  – instead, they will come in a  blaze of brilliant colors. 

Space can also  present an issue where you would  least expect it: at offshore wind farms  out to sea. However, there are obstacles  like nature reserves and shipping  routes to contend with. “There is no  other country apart from Germany  that has set such high targets in proportion  to its size, while having so little  space available for offshore wind  energy,” says Dr. Martin Dörenkämper,  group manager at the Fraunhofer  Institute for Wind Energy Systems  IWES. “Currently, the available  surface area could produce between  50 to 60 gigawatts at peak capacity,  but the expansion goals set by policymakers  call for at least 70 GW.” Of  course, the wind farms could just be  built closer together, but then they  would block each other’s wind and  become less efficient. The big question  is how far can you push it? Researchers  at Fraunhofer IWES hope to  find out. In the research project  X-Wakes, they are simulating wind  flows under various different conditions,  using a conventional weather  model that they have expanded to  represent a wind farm.