The mayor of Wildpoldsried, Arno Zengerle, is a very reasonable man. On the wall next to the mayor’s desk is a poster. It shows a windmill, and it reads: “Collect, put in order, assess, decide.” More than 20 years ago, when he became the mayor of this small, idyllic mountain village in the south of Germany, he collected knowledge, put it in order, assessed it, and then made a decision. Today, his village constitutes one of the most forward-looking projects for renewable energy and grid research. “Last week, we had visitors from Vietnam, Côte d’Ivoire, and Benin,” Zengerle notes as he scrolls through his calendar; “next week, from Myanmar and Iraq.” Delegations from all over the world come here to see how the energy solutions in Zengerle’s village could be adopted to their countries. Most of them are stunned by what they see: A quite traditional Bavarian way of life – the village has around 50 farmers – but below the surface, cutting-edge energy production and grid infrastructure.
Micro grid research
The future of the grid: It takes a village…
Soon, intelligent micro grids will not only serve their immediate environment with sustainable, cheaper, and stable energy. They will also boost the stability of the whole network. Meet Arno Zengerle, the mayor of a small village in southern Germany where Siemens is exploring the challenges to come.
Not only have the 2,500 inhabitants of Wildpoldsried become “prosumers”. Their solar panels, windmills, and a biogas-driven combined heat and power plant produce more than five times as much electrical energy as residents consume: In 2015, production was 34,344 megawatt-hours, while consumption stood at 6,406 megawatt-hours. The villagers transfer their surplus into the distribution grid and thus “feed” the neighboring villages with renewable energy. They also save 330,000 liters of oil a year that were previously used for energy supply.
The village has also become a test bed for ensuring a reliable, secure, and economical energy supply in an industrial country under fundamentally changing conditions. Together with the local energy provider and universities, Siemens is testing the capabilities of the village’s distribution grid in different scenarios. Equipped with a lithium-ion battery storage system, a diesel generator with vegetable oil operation, a backup diesel, a load bank, two controllable distribution transformers, a sophisticated measurement system, and a state-of-the-art communications infrastructure, the village’s distribution grid has been turned into a smart micro grid, a “small, closed circuit that can be separated from a larger grid for a short time, but that also works if it is constantly separated from the larger grid,” explains Markus Reischboeck, Senior Key Expert at Siemens, who’s in charge of the micro grid project in Wildpoldsried. To control these kinds of micro grids, Siemens offers the scalable Micro-Grid Management Systems as well as solutions based on SICAM automation devices.
Change in the air
In its first phase, Siemens and its partners tried to figure out how renewable energy generators such as solar panels and windmills influence the stability of the distribution grid, and how e-mobility can be used in a rural community. Now, during the IREN2 project, the questions to be answered are even more serious. In Germany, the energy transition is in full swing. In 2015, already 30 percent of the country’s electricity was produced from renewables, and the trend is as clear as in most industrial countries: The share of centrally installed, large-scale fossil power plants will be phased out and replaced by renewable, mostly decentralized, installed generation sources. By 2050, 80 percent of the electricity generated in Germany is to come from renewable sources. That produces new challenges.
“In terms of the current state of technology, we still face a major challenge,” says Torsten Sowa of RWTH Aachen University, a partner in the Wildpoldsried research project. “That’s because power systems that use renewables are not capable today of providing so-called system services, such as making reactive power available to maintain the voltage in higher-level networks. In other words, we need a new solution if we want to achieve our target for 2050.” Smart grids are needed to ensure that distributed power systems can constantly supply sufficient electricity to consumers, even as electricity production fluctuates with the weather. Unlike today’s grids, such intelligent networks will be able to balance power generation and consumption while distributing electricity, and they will do so all the way to the end-consumer level.
So far, nuclear and coal- or gas-fired power plants still play an immensely important role. They are indispensable for ensuring stable frequency and voltage. In case of a blackout, the grid is powered up “from the top” with the help of a big power plant. But what will happen in ten or twenty years, when most of the big power plants will be offline? “We must make it possible to ‘unite’ 100 small power plants into a unit whose power the network operator can use,” says Markus Reischboeck. One of the main challenges will be to convert the distribution grids into systems that are able to transport power actively, especially in case of a blackout.
While keeping voltage and frequency in the desired range, the Wildpoldsried island grid must also provide services for grid stability to the main operating grid, serving as a so-called “topological power plant” that supplies ancillary services. This will allow the local grid to replace conventional power plants for a short period. To this end, the control systems have to provide reliable renewable generation forecasts and intelligent operations schedules, and reliable real-time operational data.
Empowering remote communities
The micro grid concept does not only work in highly developed countries. In many less-developed parts of the world, such as India or Africa, it would be much more expensive to extend high-voltage lines to remote villages than to build a micro grid that can supply a village with sustainable and secure energy. In Africa, for example, around 500 million people still have no access to electricity. That’s why delegations from all over the world are going on pilgrimages to Wildpoldsried. Of course, the main factor for a micro grid in a rural environment is the security of energy supply. But another one is environment-friendly thinking. In Wildpoldsried, it all started with people like Mayor Zengerle asking themselves how to use less fossil fuels in local energy production.
Whether within an upstream power grid or as an island grid, today’s micro grid technology is paving the way for lower consumption of fossil fuels while ensuring the highest level of supply security. Renewable energy sources can be exploited to the fullest extent, while minimizing the runtime of backup generators. In the community of Ventotene in Italy, the “island grid” is not only a metaphor. The island in southern Italy with its 700 inhabitants had serious challenges concerning grid stability: It is not connected to the grid of the mainland. Before the new system was introduced, especially in summertime when thousands of tourists visited the island, the grid often reached its limits. All three factors suggesting an intelligent micro grid were in place: The community needed secure supply, reduced costs, and reduced emissions.
In 2016, Siemens put in operation a turnkey Siestorage battery storage system that allows the entire energy system to operate more economically and efficiently. In addition, Siestorage uses integrated converters to stabilize the frequency and voltage of the island’s network. The island network management is handled by the intelligent control unit providing for the optimal interoperation of storage systems, generation, and consumption – three parameters that are continuously being adapted to the actual demand. This ensures that the diesel generators, in particular, can be used in a more efficient operating mode. Because short-term peak loads are covered by power from the storage system and not from the generators. During off-peak periods, it is even possible to switch off the diesel generators completely. This saves fuel, extends the service life, minimizes maintenance, and reduces the need to stockpile fuel reserves. As a result, CO₂ emissions are lower and consumption of diesel fuel, which has to be specially transported to the island from the mainland, is significantly reduced.
Lower cost of network expansion
Of course, in many larger cities, the security of energy supplies is not as big an issue, as is the production of energy with renewables. The reductions of costs and CO₂ emissions could get institutions like university campuses or big industry complexes to introduce renewable energy capacities and form their own smart micro grids. “The capacity of our micro grids ranges from 1 megawatt for a small island to 20 megawatts for a larger community, a university campus, or a military base," says Markus Reischboeck. “A micro grid can provide up to 5,000 people with energy.”
Mayor Zengerle takes a walk through his village. He walks by the newly built playground that the village financed with the prize money secured through an ecology innovation award. “I’m very excited to be part of a forward-looking project that can answer important questions of energy security,” says Zengerle. “The results of the grid testing help to reduce the costs for network expansion by 40 percent. On a nationwide scale in a country the size of Germany, this sums up to several billion euros," he says.
In the upcoming months, the researchers will finally test the “island case”, which means that the village’s micro grid will be disconnected from the distribution grid that has been supplying it. Will that work out? “I’ve known most of the team for years now,” says Zengerle with a smile. “And I trust their engineering abilities.”