Climate-neutral powertrain for the long haul
This is information supplied by Bosch, and as always it includes some really useful information. My personal view is that hydrogen is the future for heavy vehicles but not necesarily for cars – see what you think.
Electromobility is picking up more and more speed. It is an important element in reducing CO2 emissions from traffic. But how economical is it to operate heavy-duty trucks with 40-ton payloads over long distances using only battery-electric power? Given the battery weight, long charging times, and limited range of today’s technology, electric powertrains aren’t the first choice for heavy trucks. Nevertheless, even 40-ton trucks will be able to travel more than a thousand kilometres in all-electric mode in the near future. The key to this is the Bosch fuel-cell powertrain. When powered with hydrogen produced using renewable energy, this powertrain enables the climate-neutral transportation of goods and commodities. Bosch is taking the first step in this direction by developing the fuel-cell powertrain primarily with a focus on trucks, and the company plans to start production in 2022–2023. Once they have become established in trucks, Bosch fuel-cell powertrains will then increasingly find their way into passenger cars – rightly making them an integral part of tomorrow’s powertrain portfolio.
Seven reasons why fuel cells and hydrogen are crucial building blocks of tomorrow’s mobility:
1) Climate neutrality
In a fuel cell, hydrogen (H2) reacts with oxygen (O2) from the ambient air. The energy this reaction releases is converted into electricity, which is used for driving. Heat and pure water (H2O) are other products of the reaction. H2 is obtained using electrolysis, in which water is separated into hydrogen and oxygen with the aid of electricity. Generating this electricity from renewables makes the fuel-cell powertrain completely climate-neutral. Especially for large, heavy vehicles, fuel cells have a better carbon footprint than exclusively battery-electric powertrains if the CO2 emissions for production, operation, and disposal are added together. All that fuel-cell vehicles need in addition to their hydrogen tank is a much smaller battery for intermediate buffer storage. This greatly reduces their carbon footprint in production. “The advantages of the fuel cell really come into play in those areas where battery-electric powertrains don’t shine,” explains Dr. Uwe Gackstatter, president of the Bosch Powertrain Solutions division. “This means there’s no competition between fuel cells and batteries; instead, they complement each other perfectly.”
2) Potential applications
Hydrogen has a high energy density. One kilogram of hydrogen contains as much energy as 3.3 litres of diesel. To travel 100 kilometres, a passenger car needs only about one kilogram; a 40-ton truck needs a good seven kilograms. As with diesel or gasoline, it takes just a few minutes to fill an empty H 2 tank and continue the journey. “Fuel cells are the first choice for transporting larger loads for many kilometres every day,” Gackstatter says, summarizing the advantages. In the EU-funded H2Haul project, Bosch is currently working with other companies to build a small fleet of fuel-cell trucks and put them on the road. In addition to mobile applications, Bosch is developing fuel-cell stacks for stationary applications with solid-oxide fuel-cell (SOFC) technology. One intended use for them is as small, distributed power stations in cities, data canters, and charge points for electric vehicles. If the Paris climate action targets are to be met, in the future hydrogen will need to power not only cars and commercial vehicles, but also trains, aircraft, and ships. The energy and steel industries are also planning to make use of hydrogen.
One of the decisive factors for a powertrain’s eco-friendliness and profitability is its efficiency. This is around a quarter higher for fuel-cell vehicles than for vehicles with combustion engines. Employing recuperative braking further increases efficiency. Battery-electric vehicles, which can store electricity directly in the vehicle and use it for propulsion, are even more effective. However, since energy production and energy demand do not always coincide in time and location, electricity from wind and solar plants often remains unused because it cannot find a consumer and cannot be stored. This is where hydrogen comes into its own. The surplus electricity can be used to produce it in a decentralized way, ready for flexible storage and transportation.
The cost of green hydrogen will come down considerably when production capacities are expanded, and the price of electricity generated from renewables declines. The Hydrogen Council, an association of over 90 international companies, expects costs for many hydrogen applications to fall by half in the next ten years – making them competitive with other technologies. Bosch is currently working with the startup Powercell to develop the stack, the core of the fuel cell, and make it market-ready, with manufacturing to follow. The goal is a high-performance solution that can be manufactured at low cost. “In the medium term, using a vehicle with a fuel cell won’t be more expensive than using one with a conventional powertrain,” Gackstatter says.
Today’s network of hydrogen filling stations doesn’t offer complete coverage, but the roughly 180 hydrogen filling stations in Europe are already sufficient for some important transport routes. Companies in many countries are cooperating to push ahead with the expansion, often supported by state subsidies. In Germany, too, politicians have recognized the important role of hydrogen in decarbonizing the economy and have anchored it in the National Hydrogen Strategy. For example, the H 2 Mobility joint venture will have built around 100 publicly accessible filling stations in Germany by the end of 2020, while the EU-funded H2Haul project is working not only on trucks but also on the filling stations required on its planned routes. Japan, China, and South Korea also have comprehensive support programs.
The use of gaseous hydrogen in vehicles is safe and no more hazardous than other automotive fuels or batteries. Hydrogen tanks do not pose an increased risk of explosion. It is true that H 2 burns in combination with oxygen and that a mixture of the two beyond a certain ratio is explosive. But hydrogen is about 14 times lighter than air and therefore extremely volatile. For example, any H 2 that escapes from a vehicle tank will rise faster than it can react with the ambient oxygen. In a fire test conducted on a fuel-cell car by U.S. researchers in 2003, there was a flash fire, but it quickly went out again. The vehicle remained largely undamaged.
Hydrogen production is a proven and technologically straightforward process. This means it can be ramped up quickly to meet higher demand. In addition, fuel cells have now reached the necessary technological maturity for their commercialization and widespread use. According to the Hydrogen Council, the hydrogen economy can become competitive in the next ten years, provided there is sufficient investment and political will. “The time for entry into the hydrogen economy is now,” Gackstatter says.
Special offer available for pre-order: Advanced Automotive Fault Diagnosis 5th Ed. By Tom Denton
Ideal for technicians and students, along with 25 new real-life case studies, this fifth edition includes new content on diagnostic tools and equipment: VCDS, decade boxes, scanners, pass through, sensor simulators, break out boxes, multimeter updates for HV use, and more. It explains the fundamentals of vehicle systems and components, and it examines diagnostic principles and the latest techniques. Diagnostics is an essential part of a technician’s work, and as automotive systems become increasingly complex there is a greater need for these skills.
Chapters: 1. Introduction 2. Diagnostic technique 3. Tools and equipment 4. Sensors, actuators and oscilloscope diagnostics 5. On-board diagnostics 6. Engine systems 7. Chassis systems 8. Electrical systems 9. Transmission systems 10. Case studies
Pedestrians obscured from view by vehicles, cyclists passing in front of the car, buses that suddenly approach: negotiating city traffic can quickly become a difficult task. Of all things, it could be streetlights that make urban traffic safer and provide automated vehicles with an overview of the traffic situation. This was the subject of the MEC-View research project. The project required streetlights to be fitted with video and lidar sensors, which then used advanced cellular technology to provide vehicles with critical information in real time, allowing them to detect obstacles – whether other cars, bicycles, or pedestrians – quickly and reliably. After more than three years of development, the project is now ready to present its findings. Partners in the project, which received 5.5 million euros in funding from the German Federal Ministry for Economic Affairs and Energy (BMWi), were Bosch, the consortium leader, together with Mercedes-Benz, Nokia, Osram, TomTom, IT Designers, and the universities of Duisburg-Essen and Ulm. The project’s associated partner was the city of Ulm, which for the past three years has been the testing ground for the sensors on the streetlights and the connectivity technology. The insights gained in the project will now be used to further develop automotive technology, automated driving, and cellular technology. In addition, the infrastructure the project has built up will now be available for further research projects to use.
Bird’s-eye beats worm’s eye
Reaching up to six meters in height, streetlights tower above road traffic. They have a precise bird’s eye view of developments at busy intersections, say – and it is knowledge like this that automated vehicles will need in the future. While a vehicle’s sensor systems – cameras, radar, and lidar sensors – give it precise 360-degree vision, the view from the ground – from the vehicle alone – is not always sufficient for it to see a pedestrian currently obscured by a truck, a vehicle emerging from a concealed entrance, or a cyclist approaching from behind and changing lanes quickly. “Because the vehicle itself cannot see around corners or through walls, we use the streetlight sensors to extend the vehicle sensors’ field of view,” says Dr. Rüdiger Walter Henn, who heads the MEC-View project at the consortium leader Bosch. The project partners have developed the corresponding hardware and software for this purpose; the system processes the images and signals from the infrastructure sensors, combines them with high-resolution digital maps (HD maps), and transmits them to the vehicle over the air. There, the data merges with the vehicle’s own sensor information to create an accurate picture of the situation, including all relevant road users.
Wireless data transmission
Advanced cellular technology makes extremely low-latency transmission of sensor information possible. While the MEC-View project used LTE mobile communications technology with an optimized configuration for this purpose, in the new 5G communications standard, real-time data transmission is a basic function. The core task of latency-optimized mobile communications is not only the virtually instantaneous wireless transmission of data, but also the processing of that data as close to the source as possible. This task is performed by special computers, known as mobile edge computing servers (or MEC servers for short), which are integrated directly into the cellular network. They combine the streetlight sensor data with data from a vehicle’s surround sensors and highly accurate digital maps. From this, they generate a model of the surroundings that includes all available information about the current traffic situation, and make this model available to vehicles over the air. In the future, facilities such as the city traffic control centers could be equipped with such servers, so that they can share the data with all vehicles, regardless of manufacturer, and other road users.
Seamlessly merging with trafic
In Ulm, the project partners have been testing the interaction of automated vehicle prototypes and infrastructure sensors in real traffic conditions since 2018. One intersection in the Lehr district of Ulm is notorious for its lack of good all-round visibility. The streetlights there were equipped with sensors to help automated vehicles negotiate the intersection. Vehicles approaching the difficult intersection from a side road have to merge onto the main road. Thanks to the newly developed technology, the automated prototype now recognizes road users early on and can adapt its driving strategy accordingly. As a result, the vehicle targets gaps in the traffic on the main road and merges seamlessly, without stopping. Such a development will make urban traffic not only safer, but also more fluid. The infrastructure built up during the project will remain in Ulm, where it will be available for use by subsequent research projects.
Project website with the findings: www.mec-view.de
Mercedes-AMG is implementing electric exhaust gas turbochargers in its next vehicle generation. The turbocharger features an electronically controlled electric motor which drives the compressor wheel before the wheel takes over the exhaust gas flow.
Electric exhaust gas turbocharger from Mercedes-AMG
The electric exhaust gas turbocharger was developed in partnership with Garrett Motion. The technology comes from Formula 1 and is intended to combine the benefits of a small turbocharger with fast response times that achieves relatively low peak performance and of a large turbocharger with high peak performance but delayed responses.
A slim electric motor measuring around 4 cm is integrated directly on the charger shaft between the turbine wheel on the exhaust side and the compressor wheel on the fresh-air side. The electronically controlled electric motor drives the compressor wheel before the wheel takes over the exhaust gas flow, which significantly improves responsiveness even at idle speeds and across the entire engine-speed range. The turbocharger is powered by a 48-volt on-board electrical system and can achieve speeds of up to 170,000 rpm, which enables a very high air flow rate. Along with the electric motor and power electronics, the turbocharger is connected to the combustion engine’s cooling circuit.