Technology 299 days ago

Many Alternatives, but No Solution

Alternative Energy Concepts for Individual Mobility Promise Much and Keep Little. What will be Left in the End?

The automotive industry has been experimenting for decades with alternative drive concepts for reducing greenhouse gases and lowering particulate emissions. From LPG and CNG, through FCEV and PHEV to FFV. What do all these abbreviations tell us? That we really don't have to remember the full names, as we won't be bothering ourselves with these technologies for long? Or that the industry has plenty of alternatives but no solution to the pressing problems of individual mobility? Auto mobility is stuck in a dead end with lots of side alleys that lead nowhere. Industry and politics know this, but nobody wants to address this delicate topic - due to fear of damaging a strong brand, due to fear of an electoral debacle, due to fear that we will have to admit our own technological inadequacy.

If we compare current drive concepts, we quickly establish that the zero-emissions car is not far removed from the notion of a sugar-free donut. Here, too, sugar-free does not mean "zero calories", to the same extent that zero emissions does not mean environmentally friendly.

What are the promises made by alternative fuels and can they keep them?

LPG (Liquefied Petroleum Gas) is a fossil energy carrier that occurs as a by-product of refining crude oil and natural gas. LPG is a mixture of propane and butane and is stored under pressure (2-8 bar at ambient temperature). LPG has been established in most European countries since the 1980s. Due to its lower taxation, LPG has a cost benefit over petrol and diesel, which is why it enjoys greater popularity during times of rising petrol prices.

LPG is more environmentally friendly than gasoline in its combustion. Depending on the ratio of propane to butane, a vehicle has around 15 percent fewer CO2 emissions running on LPG than on petrol.

CNG enjoys tax benefits (depending on the country) and has been used increasingly in recent years for powering vehicles. It is stored, transported and filled either as Compressed Natural Gas (CNG) - compressed to around 200 bar - or as Liquefied Natural Gas (LNG), where the natural gas is liquefied through cooling to around 160°C and kept in liquid form through storage in pressure vessels.

Natural gas consists largely of methane, which is more environmentally friendly than petrol in its combustion. Compared with burning petrol, the CO2 emissions of vehicles running on natural gas can be reduced by around five to 25 percent. Liquefaction is an elaborate process that uses up around ten to 25 percent of the gas' energy content.

Greenhouse gases for internal combustion engines

Greenhouse gases for internal combustion engines

LPG, CNG and LNG are all fossil fuels, the extraction, transport, processing and combustion of which releases greenhouse gases and CO2. Aside from the fact that these fuels are not sustainable, they are therefore also not environmentally friendly. Vehicles able to run on CNG and LNG are also more technically complex and thus more expensive. Plus, there are concerns regarding the risk of explosion in the event of accidents and restrictions in their use in places such as parking garages, domestic garages and ferries. Compared with conventional fossil fuels, their transport and storage are more technically complex and therefore more expensive.

(Photo: European Community)

With the EU's guidelines on renewable energies (>), the decision was taken in 2008 to increase significantly the proportion of biofuels, such as bioenthanol or biodiesel, in traffic applications to at least ten percent by 2020. The EU would like to increase its independence from oil-exporting nations and is keen to promote ethanol as an environmentally friendly and sustainable alternative to fossil fuels. But a study carried out by the London-based "Institute for European Environmental Policy" (IEEP) comes to a very different conclusion. (>) The study assumes that the production of biofuels will necessitate conversion of massive swathes of land worldwide into additional farmland - something not taken into account by the proponents of biofuels. The study reckons up to 69,000 square kilometres of forest, meadow and swampland would have to be converted into agricultural land in order to meet the EU's target. This equates to twice the surface area of Belgium. Enormous monocultures would be created, leading to the release of up to 56 million tonnes of greenhouse gases every year. It would be an ecological disaster.

On average, one hectare of corn yields around nine tonnes. This can be used to produce either 3700 litres of bio-ethanol (>), enough to fill up 50 cars once or to feed 50 people for a year.

The argument that only a small percentage of the cereal harvest in the EU is used for biofuels is pitted against the fact that the EU cannot cover its biodiesel needs alone and thus exports the problem by importing more than half of its raw plant material from countries like Brazil and Indonesia.

Overall, the use of biofuels - depending on location and the type of plant, as well as production processes and process energy - achieves CO2 reduction of between zero and 50 percent.

Are biofuels an isolated solution? Perhaps, yes, but certainly not across the board as this would be simply casting out the devil with Beelzebub.

BMW i8 with eDrive hydrogen fuel-cell. Photo: BMW Group.
BMW i8 with eDrive hydrogen fuel-cell. (Photo: BMW Group)

In contrast to fossil fuels, hydrogen is not a primary energy, which means that energy must be used to produce hydrogen in the first place. This obviously means transmission losses, i.e. energy is lost. The benefit of hydrogen as an energy carrier is that it generates no harmful emissions and, in particular, no carbon dioxide. This calculation only works, however, if the hydrogen is generated using renewable energies. What makes it problematic is that hydrogen is currently produced almost exclusively with fossil-based primary energy sources. Thus hydrogen drive in the form of a fuel cell delivers no environmental benefits compared with the direct combustion of fossil energy carriers. Fuel-cell vehicles are classified as climate hostile and their environmentally friendly credentials are clearly denounced. (>) Furthermore, the energy density of hydrogen based on volume is very low (approx. 1/3 that of natural gas, but has more than twice its energy density based on mass). Storing an equivalent amount of energy calls for three-times the tank size or three times the pressure required for natural gas. In order to use it as a fuel, hydrogen is therefore highly compressed (to around 700 bar) or liquefied (-253 °C). Both of these processes are not only elaborate and with certain risks attached, they also require additional energy (compression approx. 12 percent. Liquefaction approx. 20 percent). As a result, hydrogen is not an efficient energy carrier. Added to that is the fact that the establishment of an adequate hydrogen refuelling infrastructure would require significant investment.

Building a hydrogen refuelling infrastructure is costly. The cost of constructing a single hydrogen fuel station is around 19 million euros. (>)

Hydrogen-powered fuel-cell vehicles themselves are also considerably more expensive than comparable vehicles with combustion engines. The technology for the mobile storage of hydrogen is expensive, as safeguards have to be in place against insulation losses that could lead to outgassing. And even then, there are still significant fuel losses. The half-full liquid hydrogen tank of the BMW Hydrogen7 empties itself in around nine days if left unused. (>)

Toyota Mirai fuel-cell vehicle. Photo: Toyota Deutschland GmbH.
Toyota Mirai fuel-cell vehicle. (Photo: Toyota Deutschland GmbH)

At the start of this year, Toyota unveiled its first fuel-cell vehicle in the shape of the Mirai - a mid-size fuel-cell vehicle at a price of 78,540 euros (Germany). (>)

Fuel cells contain the relatively expensive raw materials yttrium, platinum and palladium, which, from an environmental standpoint, cannot be extracted and processed on a sustainable basis.

Lithium-ion Batteries
Lithium-ion battery is the overall term used for batteries based on lithium compounds. Compared with other types of batteries, lithium-ion batteries have a high specific energy, but are sensitive to both deep discharge and overcharging. The problems surrounding the thermal collapse of lithium-ion batteries, which were responsible for fires in Tesla vehicles and Boeing 787 Dreamliners, are still very much an issue. Nevertheless, they are the preferred energy storage medium for electric mobility, as conventional nickel-cadmium and nickel-metal hydride batteries are too heavy, too toxic or too big.

The main benefit of electric vehicles relative to vehicles with combustion engines is most certainly the absence of local exhaust emissions. However, this does not mean that battery-powered electric vehicles are environmentally friendly.

Knee-jerk incentive programmes and political initiatives are therefore missing the target. Environmental politicians who promote the establishment of buying incentives, widespread installation of battery charging points and social benefits in order to bring forward the market introduction of electric drives are missing the point that today's electric vehicles are in no way environmentally neutral on-the-road. The primary energies and the raw materials used to produce the lithium-ion batteries certify modern electric vehicles as anything but environmentally neutral. If you take into account the entire lifecycle of a lithium-ion battery, the environmental risks - depending on the cell chemistry - become blatantly obvious in terms of both raw material extraction and recycling. (Handbook of Clean Energy Systems - Volume 5 Energy Storage, Edition: 2015). (>)

Spearheaded by incentive programmes, recent years have seen repeated and unsuccessful pushes for electric vehicles. But it's not only the high purchase price, the unfeasible reduction in maintenance costs and the above-average loss in value that are keeping many consumers from buying an electric vehicle.

(>) The range and charge duration problems of lithium-ion batteries are dulling enthusiasm for electric vehicles, and nothing is going to change as long as the performance of these vehicles remains unsuitable for everyday use.

The Tesla Gigafactory will allegedly start building batteries for up to 500,000 vehicles starting 2020. This would equate to around 0.5 percent of new vehicles registered every year worldwide.
The Tesla Gigafactory will allegedly start building batteries for up to 500,000 vehicles starting 2020. This would equate to around 0.5 percent of new vehicles registered every year worldwide.

Cost is another factor. Higher production volumes have brought about a double-digit price drop per kWh for lithium-ion batteries in recent years, placing them currently around the 265 euro per kWh mark. However, a 60 kWh battery like the one in the Tesla S still costs around 15,900 euros - just for the battery itself, without its associated systems. Raw material costs account for roughly 70 percent of the battery price.

Construction of a suitable charging infrastructure has to account for compatibility with the different battery and charging systems from the respective manufacturers of electric cars. A single public charging station comes in at around 25,000 to 50,000 euros. These are infrastructure costs that must be borne by the general public. Drivers themselves pay a further 800 to 2,500 euros for their own domestic charging station, while drivers of electric cars who have to use public parking spaces will have to compete for charging stations.

Manufacturers currently guarantee battery life of around five years or from 50,000 to 100,000 km. According to literature, around 5,000 cycles can be achieved with a capacity loss of 20 percent, which means the expected life of the battery is roughly eight years. (>) The key factor impacting battery lifespan, however, is charging - powerful charging currents, such as those required for rapid charging (<30 min), shorten battery life enormously.

Industry and politics know that lithium-ion batteries are not the be-all and end-all. Research is ongoing worldwide into a new generation of electricity storage media. Industry focus is more on optimising performance then the environmental aspect. All future concepts are based on lithium compounds. However, if demand grows, this raw material could become scarce as soon as 2050.

nanoFlowcell Holdings Ltd has therefore adopted a totally different approach, conducting research into a battery solution for mobile use that permits complete flexibility, performs effectively in everyday use and is also 100 percent environmentally neutral.

Flow Cells
Flow cells have been used for many years for energy storage in solar and wind energy installations. Due to their low energy density and the physical dimensions of the cells themselves, flow cells were previously unsuitable for mobile applications - such as electric vehicles.

Over many years of research work, nanoFlowcell Holdings Ltd has developed a compact flow cell that has an energy density many times higher than conventional fuel cells. At its core is an electrolyte compound with an energy capacity comparable to that of modern lithium-ion batteries. The electrolyte liquid, named bi-ION, comprises metallic salts in an aqueous solution and is harmful neither to health nor the environment. Moreover it is neither combustible nor explosive. In combination with the cell itself - the nanoFlowcell - the system produces an output of 600 Wh per litre of electrolyte liquid. Modern electric cars could drive 200 km/h on it and would still have a range of more than 1000 kilometres. It is a zero-emissions and sustainable source of energy.

Industrial production costs for the nanoFlowcell stand at an estimated 600 euros. By selecting the ideal energy storage medium, electric vehicles could therefore not only save weight, but also cost significantly less. A car driven by nanoFlowcell is also less expensive to maintain than one powered by fossil fuels and other alternative fuels. One litre of bi-ION equates to roughly 600 Wh and could be made for around 0.10 euros.

Refuelling the QUANTiNO test vehicle with bi-ION electrolyte liquid.
Refuelling the QUANTiNO test vehicle with bi-ION electrolyte liquid.

Due to its product characteristics, there are no special requirements for the transportation and storage of the electrolyte liquids. Modifications to the existing refuelling infrastructure would also be inexpensive (as described by Simon Árpád Funke and Martin Wietschel in ("Assessment of the construction of charging infrastructure for redox-flow-battery-based electric mobility"). (>) Drivers will not have to relearn anything and will be able to fill up a nanoFlowcell vehicle just like a conventional petrol or diesel-powered car in a little more than four minutes.

Plus, flow cells have minimal self-discharging, no memory effect and, in the case of bi-ION, the electrolyte liquid has an almost infinite shelf life.

The nanoFlowcell based on flow cell technology represents a new generation of energy storage, characterised by the optimisation of performance and environmental factors. nanoFlowcell shows how uncompromising electric mobility can work, how it can be attractive to consumers without the need for incentives and can be implemented by manufacturers economically and at no additional cost to the general public.

Characteristics of the various drive systems (1 = very good. 5 = very bad)

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