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Grid stabilization through hydropower plants

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News, Water & Waste Water

In 2022, the last nuclear power plants in Germany will be taken off the grid – meaning that the power supply system will also lose instantaneous reserve. This system service – in addition to control power – ensures the stability of the grids in the event of disruptions. As a study by the RWTH Aachen University has now shown, the hydropower plants in Germany can compensate for a disruption, for example due to an unplanned power plant outage of up to 500 megawatts (MW), in terms of instantaneous reserve. This corresponds to the output of a medium-sized coal-fired power plant. They thus make a relevant contribution to future grid stability and security of supply.

Instantaneous reserve is the term used to describe the power reserve available without delay in a power transmission system. It results from the inertia of the rotating flywheel masses of the synchronous generators of conventional power plants. If there is an abrupt change in load in a power grid, the power deficit cannot be compensated immediately by regulating power plant output. This is because this is always associated with a certain delay time. Therefore, in order to prevent instabilities and interruptions, sufficient kinetic energy from rotating flywheel masses of power plants must be available in the supply system immediately after the disturbance.

Hydropower plants as a balance to volatile power generators

From the point of view of generation volumes, wind energy and photovoltaic plants are considered to be the main pillars of future renewable energy production. However, these plants, which are usually connected by power electronics, do not yet provide instantaneous reserve according to the current state of the art. Hydroelectric power plants, on the other hand, are capable of doing so.

A team led by Professor Albert Moser, Chair of Transmission Networks and Energy Economics at the Institute of Electrical Systems and Networks, Digitalization and Energy Economics (IAEW) at RWTH Aachen University, has now determined and quantified the instantaneous reserve of hydropower plants in Germany. The calculations are based on 7,988 hydropower plants with a total of 6.28 gigawatts net nominal capacity recorded in the market master data register of the Federal Network Agency. Among other things, the scientists determined the stored kinetic energy of the hydropower plants, which can be determined from the inertia constant and the rated power of the generators.

According to the calculations, a kinetic energy of around 10.32 gigawatt seconds (GWs) is stored in the rotating masses of the hydropower plants in Germany. By way of comparison, the Weisweiler Block H lignite-fired power plant has a kinetic energy of 2.4 GWs, while the Isar/Ohu 2 nuclear power plant has 8.88 GWs. The kinetic energy provided by the hydropower plants thus corresponds to the instantaneous reserve of a nuclear power plant.

The study was led by Martin Knechtges and Stefanie Samaan. It further shows that a disturbance event of 462.5 MW could be absorbed by the hydropower plants alone in terms of instantaneous reserve, taking into account the frequency dependence of the grid loads. Their held instantaneous reserve is sufficient to sufficiently limit the resulting frequency change rate and deviation. “German hydropower plants also contribute at this level to the control of larger power deficits, for example grid disconnections. Further contributions to mastering must then still be provided from other plants,” summarizes Martin Knechtges, research associate at IAEW.

Small decentralized hydropower plants stabilize Bavarian power grids

In addition, the researchers point out, particularly for Bavaria, that in terms of future grid structures and the self-sufficient supply of small cellular grids, the decentralized hydropower plants available can contribute to stable grid operation.

“The study shows once again that hydropower plants fulfill important system services for grid stabilization, especially against the background of the shutdown of nuclear power plants in 2022 and subsequently of coal-fired power plants. In addition to instantaneous reserve, black start capability is also worth mentioning in this regard, for example.”

– Fritz Schweiger, Chairman of the Board of the Association of Hydropower Plants in Bavaria (VWB) e.V.

This means that after a large-scale power outage, hydropower is technically capable of supporting the reconstruction of the power supply. “However, the study also shows that existing hydropower alone cannot provide the necessary momentary reserve in the power supply system. Expanding electricity generation from hydropower would already have an efficient solution component for this. However, the other renewable energy sources will also have to make their contribution in the future. Now it is up to the engineers to find out how this can be ensured with modern power electronics,” states Detlef Fischer, Managing Director of the Association of Bavarian Energy and Water Industries (VBEW) e.V..

The study “Determining the instantaneous reserve of hydropower plants in Germany” at the Institute of Electrical Systems and Networks, Digitalization and Energy Economics at RWTH Aachen University was carried out on behalf of the German Hydropower Association (BDW) e.V., the “Hydropower Yes Please!” initiative in the Bavarian Energy and Water Management Association (VBEW) e.V. and the NRW Water Utilization Interest Group.

News Processing Technologies

Rapid further development of connectors

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The Connector Congress in Würzburg has come to an end with the participation of rolled products manufacturer Kemper.

“After more than a year of abstinence, finally the first presence event in the industry. A piece of normality that many have longed for all this time. We are all the more pleased to have had many interesting discussions and made new contacts.”

– Dr. Stephan Hansmann, Head of Technical Marketing

Miniaturization is one of the much-discussed megatrends, as a result of which more and more plug contacts are being realized in the smallest possible installation space. Accordingly, there was great interest at the Kemper booth in HP bronzes, which have improved formability compared to standard alloys without sacrificing strength. With this property, Kemper HP bronzes offer themselves as an optimal material for increasingly smaller connector systems. “Connectors in particular are developing rapidly and will actively accompany the energy transition,” Hansmann is certain. “This includes, for example, smart connectors with additional functions, where, for example, connectors communicate with each other even before the plugging process has taken place.”

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News Processing Technologies

Great catch-up potential for eMobility in public transport

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Around a hundred thousand diesel buses are still on Europe’s roads with outdated technology. At the same time, the number of e-buses is rising significantly. It is hardly surprising that electromobility is on the rise. After all, the call for sustainable mobility is getting louder and louder. With the MAN Lion’s City 12 E and the all-electric 18 E articulated bus, MAN Truck & Bus offers the right solution for the urban transport of the future.

Electromobility is electrifying more and more people. This is clearly demonstrated by the rising registration figures for e-cars. But e-mobility is not only gaining momentum in private transport. In public transport, too, more and more operators are turning to e-vehicles, as recent figures from the umbrella organization of European vehicle manufacturers (ACEA) show. Based on bus registration figures, the association reported that sales of electric buses in the European Union increased by 18.4 percent in 2020 compared to 2019. The share of diesel engines, on the other hand, decreased by almost ten percent (source: “ACEA buses by fuel type full-year 2020,” 30 March 2021).

“Overall, the total European market for electric buses was more than 2,000 vehicles last year. And the trend is clearly upward. We expect half of all new city buses to be alternatively powered by 2025.”

– Rudi Kuchta, Head Business Unit Bus

Despite the rising eBus numbers, diesel buses are still by far the most common on EU roads. According to ACEA, there were a total of more than 690,000 buses in 2019, with an average age of 11.7 years – 94.5 percent of which were powered by diesel, and 0.6 percent purely electric (source: ACEA Report “Vehicles in use Europe,” January 2021). “The figures and our experience show that electromobility is on the rise. At the same time, they also make clear what great potential it still holds. Replacing diesel buses with outdated technology with modern electric buses will help enormously to reduce CO2 emissions,” says Kuchta, adding, “This is a key building block in tackling climate change.” After all, with an annual mileage of 50,000 to 60,000 kilometers and a consumption of 36 to 49 liters per 100 kilometers, which varies depending on use, topography and vehicle variant, an eBus traveling with zero local emissions can save around 60 to 80 tons of CO2 per year – compared to a diesel bus and assuming the current electricity mix.

The bus is already considered the most environmentally friendly and economical means of transport. However, local public transport operators and municipalities have it in their own hands to cut CO2 emissions even more and thus contribute to climate protection. The European Union has also recognized this and passed the Clean Vehicle Directive. This provides for binding emission standards in municipal fleets – the legislation has been in force since August 2021. Cities must thus set their course for emission-free mobility. The goal: to move from “low emission” to “no emission.”

“More and more public transport companies have understood this and are relying only on battery-powered city buses for new purchases. Or they are setting clear time targets for converting the entire fleet to zero-emission drives,” says Kuchta. One example is Verkehrsbetriebe Hamburg-Holstein (VHH), which has been procuring only locally emission-free, battery-powered buses since 2020. The goal is to convert the entire bus fleet to zero-emission drives as far as possible by 2030.

In order to provide transport companies with the best possible support on their way to zero-emission mobility, the company offers an overall concept that brings together holistic eMobility consulting and tailored, forward-looking solutions. Because for MAN, too, the future of urban mobility is electric. “We are convinced that electromobility is the key technology for commercial vehicle transport of the future. For this reason, we are constantly driving technologies and progress forward together with our customers,” says Rudi Kuchta. The focus here is on the MAN Lion’s City E – and thus the all-electric solution for public transport.

For months now, the MAN Lion’s City E has been demonstrating in more and more cities throughout Europe how excellently it masters urban traffic and how easily it can be integrated into existing processes. During an MAN eBus test drive that took place in Munich in May of this year, it also cracked the 550-kilometer mark under realistic everyday conditions with just one battery charge. “The issue of range plays an essential role for our customers.

After all, on lines that were previously served by a single vehicle with an internal combustion engine, only one electric vehicle will be on the road in the future. During the MAN Efficiency Run, our eBus impressively demonstrated how suitable electric mobility already is for everyday use,” says Kuchta. Even with a realistic range of “only” 400 kilometers in regular operation, the bus could cover 98 percent of the routes served by MAN customers without intermediate charging. And it would then be charged in the depot – with the advantage that operators would not have to invest in additional charging infrastructure in the city area.

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News Processing Technologies Water & Waste Water

WPL wastewater technology is selected by major logistics hub

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Technology from water recycling specialist WPL, a WCS Group company, was selected by DP World London Gateway to provide enhanced ammonia removal to protect sensitive waters in the Thames Estuary. 

DP World London Gateway is a smart logistics center on the north bank of the Thames in Thurrock, Essex, 25 miles from central London. The water recycling specialist will supply a bespoke treatment plant for a new freestanding warehouse for 150 office workers, currently under construction at the logistics center. The plant will be able to handle a flow of 7.5 m3/d for 100 population equivalents.

The treatment plant will discharge into an environmentally sensitive swale that empties into the Thames Estuary and must meet the Environment Agency’s stringent standards of 15:15:03 mg/l for ammonia and suspended solids.  The water specialist will provide an underground HiPAF (High Performance Aerated Filter) system for ammonia removal, as well as a metering unit and sand filter to further improve the final effluent in accordance with site-specific permit requirements. The design also includes a small pumping system due to the depth of the incoming effluent and a pumped backflow chamber.

Dominic Hamblin, WPL’s technical director, said, “DP London Gateway is a key logistics hub and we are pleased to be able to deliver this environmental solution on site on its behalf.

“WPL’s modular HiPAF product range meets the stringent European standards for permitting wastewater without the use of chemicals. The technology is regularly used by UK water utilities and is a good choice for sensitive sites such as marshes, which are shallow and not heavily diluted.

“The HiPAF’s compact design allows it to be installed in locations where space is at a premium, such as a busy commercial area. In addition, our sand filters are designed to remove excess suspended solids and biological oxygen demand when permit standards are above what would normally be expected from a biological process. 

“Once operational, the plant will provide robust wastewater treatment while being quiet, visually unobtrusive and easy to maintain. WPL’s wastewater treatment plant is being built by Readie Construction. Construction is scheduled to begin before the end of 2021 and is expected to take 12 weeks.

“DP World London Gateway is a high-profile site surrounded by sensitive water bodies. We are therefore pleased to be working with WPL to install on-site wastewater treatment for the new warehouse building.”  

– Giuseppe Orlando, Project Manager 

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