Audi future energies
Audi future energies
Anyone planning for future sustainable mobility first needs to adopt a new and broader perspective. For example, Audi no longer just considers the CO2 emitted while driving. Rather, it analyzes the entire life cycle of a car – from its development and production to the phase of customer use and finally recycling.
A central issue in this comprehensive analysis relates to the origins of the types of energy used to drive vehicles. In the case of electrically powered cars, for example, environmental impact is only really improved if the electricity they consume was generated from renewable resources. Following this idea to its logical conclusion, it becomes clear that the focus must shift towards new types of fuels.
This realization has motivated Audi to pursue two courses of action. Firstly, the brand with the four rings is actively engaged in projects with third parties involved in the sustainable production of electricity. Secondly, Audi is the world’s first carmaker to become directly involved in the development and production of renewable fuels that do not rely on biomass. Audi is addressing the entire range of drive technologies here, and the future fuels are called Audi e-power, Audi e-hydrogen, Audi e-gas, Audi e-ethanol and Audi e-diesel.
The first step is the Audi e-gas project, in which the Ingolstadt company is producing an entire chain of sustainable fuels. They begin with wind, water and carbon dioxide sourced from a biogas plant. The end products are renewably generated eco-electricity (Audi e-power), hydrogen (Audi e-hydrogen) and synthetic methane (Audi e-gas) which can power vehicles like the new A3 Sportback TCNG that will launch in 2013.
Over the mid-term, Audi also wants to create options for replacing liquid fuels by innovative renewable fuels that are no longer energy crop-based and do not compete directly with food production.
Right now, the brand is working with a specialist partner from the USA to produce synthetic ethanol (Audi e-ethanol) and synthetic diesel (Audi e-diesel).
The Audi e-gas project
The Audi e-gas facility that is currently being built in Werlte in the Emsland region will be operated with renewable electricity (e.g. from wind energy and solar energy). Expansion into the area of renewable energies is increasing the share of volatile energy sources – sometimes there is a surplus of electricity while at other times a shortage exists. The facility with its electrical power consumption of about 6,000 kW will preferably draw electricity whenever there is an electrical surplus. Then the facility could serve as a means for long-term storage of renewable energies, and this would solve one of the central problems of the transition to new energy sources.
The first step involves converting the electricity to produce renewably generated hydrogen by electrolysis – Audi e-hydrogen – which will be the fuel used to power future cars with fuel cell drive systems such as the Audi Q5 HFC technology platform. In this car, two high-pressure cylinders store the hydrogen under 700 bar pressure; a polymer electrolyte membrane fuel cell (PEM), which produces 98 kW, supplies the energy for the electric drive. Two electric motors output a system power of 90 kW and 420 Nm (309.78 lb-ft) of torque.
However, the infrastructure needed to supply hydrogen is lacking today. Audi is solving this problem by adding another innovative process step: combining hydrogen with CO2 in a methanation system (downstream of electrolysis) to synthesize renewable methane – Audi e-gas. This natural gas substitute can be locally fed into the natural gas network to store the energy.
The Audi e-gas facility in Werlte, which Audi is now constructing with system builder SolarFuel, will be the world’s first facility to convert renewable electricity and CO2 into a synthetic natural gas that can be fed into the natural gas network on an industrial scale.
The Audi facility obtains its CO2 from a biogas plant. The input material for the biogas plant is not energy crop plants, rather it is organic waste. This avoids any sort of competition with food production. The CO2 is a waste product of the biogas plant that would otherwise be released into the atmosphere. The Audi e-gas facility uses the CO2 as a feedstock for the fuel. This makes Audi e-gas a climate-neutral fuel – when it is combusted in the engine, the amount of CO2 emitted is precisely the amount consumed by the e-gas facility beforehand.
Audi e-gas is an energy-rich fuel that is chemically identical to the fossil fuel methane, the primary constituent of natural gas, and it is excellently suited for powering internal combustion engines. According to forecasts, beginning in 2013 the facility in Werlte will produce about 1,000 metric tons (1102.31 US tons) of methane per year, and in the process it will chemically bond 2,800 metric tons (3086.47 US tons) of CO2. That amount of renewably generated Audi e-gas could power 1,500 Audi A3 Sportback TCNG vehicles for 15,000 kilometers (9320.57 miles) per year in CO2-neutral driving. In 2015, Audi plans to launch a second TCNG model on the market that is based on the A4.
The German energy industry could also benefit from the conceptual approach of the Audi e-gas project over the mid-term, because it must address the open issue of how to store eco-electricity efficiently and independent of location. When a lot of sea breeze is blowing, electrical overcapacities could be converted to Audi e-gas and be stored in the public gas network – with its 217 Terrawatt-hours of energy capacity, it is by far the largest energy storage network in Germany. If desired, it would be possible to convert the energy from the gas network back into electricity at any time.
The potential of electricity-gas coupling to store large amounts of wind or solar energy can provide tremendous impetus to renewable energies. The Audi e-gas project could easily be implemented in any countries in which natural gas networks exist.
The Audi A3 Sportback TCNG
The Audi A3 Sportback TCNG represents the most advanced level of natural gas powered technology in all aspects, beginning with storage of the fuel. Its two pressure tanks, placed under the cargo space floor, each hold about eight kilograms (17.64 lb) of natural gas.
In keeping with Audi’s ultra lightweight design principle, polymer composite pressure tanks are used. They store gas at pressures of up to 200 bar and weigh around 70 percent less than conventional natural gas tanks – each tank is some 27 kilograms (59.52 lb) lighter. Their structure consists of a new type of matrix. The inner layer consists of gas-impermeable polyamide polymer, while a second layer of carbon fiber reinforced polymer (CFRP) gives the tank its extremely high strength; a third layer of glass fiber reinforced polymer (GFRP) provides rugged protection against damage from the outside. A high-strength epoxy resin is the adhesive which is used to join the CFRP and GFRP materials.
A second highlight of the Audi A3 Sportback TCNG is its electronic gas pressure regulator. This compact and lightweight component reduces the high pressure of the gas flowing from the cylinders down to around five to nine bar in two stages. It ensures that the right pressure is always present in the gas rail and at the injector valves – low pressure for efficient driving in the lower speed range, and higher when the driver calls for more power and torque. If the pressure in the tank drops below around ten bar, the engine management system automatically switches over to gasoline operation. The Audi A3 Sportback TCNG is bivalent; despite the engine being optimized for natural gas operation, it offers the same power and torque values when gasoline is used.
The car can cover over 400 km (248.55 miles) in natural gas mode and, if necessary, another 780 km (484.67 miles) with gasoline. This adds up to a total driving range equivalent to that of an Audi A3 TDI. Two indicators in the instrument cluster inform the driver of fuel tank levels at a glance. The filler necks are placed under a common fuel door.
The engine is based on the newly developed 1.4 TFSI. Key modifications relate to the cylinder head and turbocharging; the injection system and catalytic converter are specially configured for natural gas operation as well. With 81 kW (110 hp) and 200 Nm (147.51 lb-ft) of torque, the A3 Sportback TCNG accelerates to a top speed of over 190 km/h (118.06 mph). The five-door premium compact car embodies Audi’s full technological expertise. The ultra lightweight design technology gives it a low weight, and it sets new standards in its segment in terms of its infotainment and driver assistance systems.
The highly efficient Audi A3 Sportback TCNG consumes a mere 3.6 kg (7.94 lb) per 100 km of natural gas or Audi e-gas – the fuel that is created in the Audi e-gas project. With either fuel, CO2 tailpipe emissions are less than 100 grams per km (160.93 g/mile). The greenhouse gas balance is even more attractive in a well-to-wheel analysis that accounts for all factors from the fuel source to the car’s wheels. When the A3 Sportback TCNG is powered by Audi e-gas, no more CO2 is released than was chemically input in its production beforehand – creating a closed loop. When the energy required to build the e-gas facility and wind power generators is included in a comprehensive analysis, CO2 emissions are still less than 30 grams per km (48.28 g/mile).
Buyers of the Audi A3 Sportback TCNG will presumably obtain the e-gas at a public CNG refueling station via a certified ecological accounting method, similar to the method currently in existence for obtaining eco-electricity. When paying for the e-gas with a special fueling card, the transaction is centrally recorded, and the amount of e-gas purchased is debited from the amount of e-gas that the e-gas generating facility has fed into the natural gas network.
Audi e-diesel and Audi e-ethanol
The problem is very familiar: the combustion of conventional fuels based on petroleum releases carbon dioxide into the atmosphere. Current ethanol and diesel from renewable raw materials such as corn and rapeseed, generally achieve a better environmental balance, because the plants previously absorbed the CO2 that is released in combustion. But these fuel sources require costly processing and compete with food agriculture. Over the long term, they cannot be a solution in a world witnessing steady population growth.
A radically new solution is needed to produce fuels for future CO2-neutral mobility where the ‘feedstock’ for the fuel is entirely renewable. Audi is developing such a solution in a partnership with Joule, a US-based company producing fuels in a patented process that involves special microorganisms in a highly-scalable modular system.
The process is relatively simple: use the energy from the sun to convert CO2 and non-potable water into liquid fuels. At the heart of this process are photosynthetic microorganisms (each one of around three thousandths of a millimetre in diameter). However, instead of using photosynthesis to grow more cells, the microorganisms continuously produce fuel. The inputs for this process are sunlight; industrial waste CO2 from sources such as industrial plants and brackish or sea water. Critically, there is no need for agricultural land or fresh water.
The special microorganisms have been engineered to directly produce ethanol and diesel-range paraffinic alkanes – important components of diesel fuel – directly from the carbon dioxide. The fuel is secreted by these organisms, which is then separated from the water media and concentrated. No further manufacturing steps are required.
This technology makes Audi e-diesel and Audi e-ethanol come to life. For example, the e-ethanol project delivers a product with the same chemical properties as the bioethanol that is already established on the market, with the decisive advantage that it is produced without biomass. It will be used as a blend with fossil-fuel gasoline at percentages up to 85% in the case of vehicles able to use E85 fuel.
Along with the development of the Audi e-ethanol project, Audi is also working with Joule to produce a sustainable diesel fuel to support the Audi e-diesel project. A great strength of this product is its purity. In contrast to petroleum-based diesel, which is a mixture of a wide variety of organic compounds, this ‘drop-in’ fuel is free of sulfur and aromatics. Moreover, thanks to its high cetane number, a high-performance parameter, the fuel is very easy to ignite and its chemical composition permits unlimited blending with fossil-fuel diesel.
Audi e-diesel will result in a fuel that works seamlessly with existing Audi TDI clean diesel systems, posing no additional automotive engineering challenges.
Audi and Joule have commissioned a demonstration facility in the US state of New Mexico – in an unfertile region with a high level of annual sunlight. The facility is soon to begin operations with the production of sustainable ethanol. The productivity rates have shown decisive advantages over bioethanol. In addition, regions that are unsuitable for agriculture, e.g. desert regions, could be utilized for energy production.
The partnership between Audi and Joule has been in place since 2011. Joule has protected its technology with patents for which the brand with the four rings has acquired exclusive rights in the automotive field. Collaborative work includes technical support as well. Audi engineers with extensive know-how in the area of fuel and engine tests are helping to develop marketable fuels.
In April 2010, Audi joined the international consortium Desertec Industrial Initiative (Dii GmbH). Its long-term goal is to generate climate-friendly solar energy in the deserts of North Africa and the Middle East. Audi is the only automotive manufacturer in the world to be named an Associated Partner of the consortium; the brand is initially working on creating suitable conditions and building up infrastructure.
In the deserts of the Middle East and North Africa alone, the sun radiates an energy equivalent to about 630,000 TWh over the course of a year – which is 30 times the total amount of electricity generated worldwide in 2010. It has been calculated that solar-thermal generating plants operating in the earth’s most sun-intensive regions could meet current global electrical requirements with an operating area of 83,000 square kilometers (34,046 square miles) – approximately the land area of Austria.
The industry initiative has set a goal of supplying most electrical needs for North African countries and the Middle East and a smaller share for Europe from solar and wind power. Audi sees great potential for sustainable energy supplies in this project.
The brand with the four rings wants to use a portion of the electricity from the Desertec project to manufacture and drive its e-tron vehicles. If necessary, excess generating capacity from solar plants could be stored in the natural gas network – based on the principle of electricity-gas coupling that will be implemented in the Audi e-gas project in Werlte starting in 2013. Another Audi e-power strategy is to partner with companies that produce components for solar-thermal power plants – a technology that enables flexible electrical production.
Life cycle assessment
Audi keeps a close eye on environmental factors even during the development of vehicles. An assessment is made of each model’s environmental impact over all phases of its life cycle – development and production of the vehicle, recycling and – the most important factor – its operating phase. It is here in particular that the lightweight and efficient Audi models play out their strengths, especially when they are powered by renewable fuels that Audi is driving for the future.
This environmental footprint, also known as an eco-balance or life cycle assessment (LCA), analyzes the environmental effects of a product over the course of its entire life cycle. It serves to quantitatively assess such environmental aspects as greenhouse gas emissions (including CO2), energy consumption, acidification and summer smog. In generating its life cycle assessments, Audi applies a standardized process that conforms to the international ISO 14040 series of standards.
Today, the general public is very critically evaluating cars based on their fuel economy. Audi is taking an even longer view and is no longer simply concerned with CO2 emissions that escape from the exhaust system while driving. Rather, all aspects are considered: the procurement of raw materials, production of individual parts and their composition, and the energy flows in production facilities, recycling and the operating phase.
In its production area, Audi strictly adheres to the principle of sustainability. Large building roofs are equipped with photovoltaic systems. Many efficiency and energy recovery technologies are at work at plants in Ingolstadt and Neckarsulm; both production sites make use of district heating distribution systems on a large scale. Car trains to the port of Emden are powered by sustainably produced electricity, and recycling efforts have been exemplary for many years now – every Audi is 95 percent recyclable.
The customer use phase is crucial to the environmental balance of a vehicle, since about 80 percent of emissions occur in this phase. Large improvements can be realized by optimizing vehicle weight, increasing drive efficiency and in producing fuels and electricity.
This is where Audi’s strengths play a crucial role – in ultra-lightweight design, efficient drive systems and future renewable fuels. In the new Audi A3 – which has been made up to 80 kg (176.37 lb) lighter than the previous model, depending on the engine version – greenhouse gas emissions have been reduced by up to nine percent (in the 1.4 TFSI). For the first time at Audi, the A3 is being equipped with a new drive version – a natural gas engine. The TCNG model can be powered by Audi e-gas, the first representative of Audi e-fuels that achieve an even better environmental balance. When the A3 Sportback TCNG is powered by
The weight of the Audi A6 was also trimmed by up to 80 kg (176.37 lb) – its body consists of over 20 percent aluminum. Although initial production of this lightweight material requires a higher energy input than steel sheet metal, improved fuel economy overcompensates for this effect after just a short number of miles driven. In the A6 3.0 TDI quattro with S tronic, the bottom line on greenhouse gas emissions is a 13 percent reduction, which represents a seven metric ton (7.72 US ton) reduction in CO2 equivalents.
At the end of a vehicle’s life, the aluminum components can be recycled with low energy input and no compromises in quality. The ASF body contains 38 percent secondary aluminum – a prime example of eco-friendly lightweight design as Audi understands it.
The equipment, data, and prices specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.