Hybrid, Electric or Hydrogen?

There is now an updated page on hydrogen vs battery electric cars, and this page is being refocused to be more specific on the option of hybrids.

It seems most who believe in hydrogen cars do not actually understand the reality of the technology, and that hydrogen powered cars are a form of electric cars. This post looks at technologies changing the auto industry, the pros and cons of Hydrogen, Battery Electric, current Hybrids, and even Hydrogen Hybrids.

Contents:

  • Hydrogen
    • Background
    • The Case Against
    • The Case For
  • Battery Electric
    • The Case For Plug In Hybrids
    • The Case Against
    • On Balance
  • Plug In Hybrid
    • Non-plugin
    • The case for
    • The case against
  • Hydrogen Hybrid
    • what and why?
    • an answer to range anxiety?
      • long range, fast refuel
    • fuel costs/ fuel storage costs
    • refuelling stations: the elephant in the room
    • on balance
  • Conclusion

The Case For Hydrogen. – more on 0+h

Low Weight: The key benefit of hydrogen is that the stored energy is much lighter that any alternative. The video highlighiting the problems of using hydrogen, quotes the difference at over 200x the stored energy per kg compared to batteries. That is a huge difference, and results in hydrogen being a viable option where the difference in the weight of stored energy is suffiently important, the cost of electricty is extremely low, or a combination of these two factors. Clearly, for aeroplanes, that weight difference for the amount of energy required for a flight could easily the cost of the extra energy needed to extract and liquify hydrogen and other inefficiencies.

Fast Refueling. While conventially battery recharging can take hours and even over a day in some cases, refueling using hydrogen is similar in time to current refueling with petrolleum, diesel fuel or avgas.

On Balance: Hydrogen

The case for hydrogen requires extremely cost (and environmentally friendly) electricity supply, or an extremely high cost penalty for the weight of penalty of other methods of storing electricity, or a combination of both factors. It is not clear where these factors combine, but this is further examined in ‘hydrogen hybrid’ below, after considering the arguments for and against other alternatives.

Battery Electric

The Case For Battery Electric

Efficiency: Conventional batteries are highly efficient, and the entire pathway from energy supply to electric propulsion is the most efficient system available.

Charging at home: Convential batteries are simple to charge anywhere there is time and electricity. This allows for charging at home using the well established and efficient utility electicty grid. It has even been suggested ‘off peak’ charging of EVs cpould improve grid utilisation and potentially even lower electricty pricing per kw/h to homes.

Best Solution for Predominant use case: For many people, battery electric provides the optimum solution with lost cost and convenient refuelling for almost their entire use of a car, even with short range batteries. Longer range batteries are only needed by most people for very rare long road trips.

The Case Against Battery Electric.

Road Trips (Charging away from home): Charging when parked other than at home is a challenge, but one with a variety of solutions. The biggest challenge is charging during a journey. There are recharging stations, but the time to recharge means these stations would need an enourmouse number of bays to service the same number of vehicles currently serviced at petrol/diesel fuel pumps. Consider a current fuel stop with, for example, 8 busy pumps. If the same number of vehicles are to be refuelled, and it takes ten times as long per vehicle, then 80 ‘pumps’ would be required. Currently it can take over 20 times as long per vehicle, even with the fastest recharging, and distance per refuel is lower, so vehicles need ‘refuelling’ more often.

Range: With charging during a journey problematic, range becomes extremely important. But range comes at a cost in terms of weight. While fossil fuelled or hydrogen fuelled vehicles have carry capacity for long journeys, a large battery is heavy, and just as heavy even when not charged. A common car usage pattern would be 9 out of 10 days requiring only 50km range, and the maximum available range (for example for an electric vehicle say 400km) would only be needed less than 1 day in 30. Despite only being needed 1 day in 30, a vehicle will typically need to provide for that maximum range. This means the extra battery weight to provide the rarely needed extra 450km of range needed must be carried as ‘dead weight’ or ‘insurance’ 9 days out of 10. This ‘rarely needed’ range has a negative impact on efficiency.

Range Anxiety: Anxiety is where the worry or stress felt is beyond the level appropriate for a problem or possible problem. While balancing actual range against weight is a real problem, there is also ‘range anxiety’ is disproportionate fear of insufficient range. Imagine you had always only been able to charge your mobile phone once per week, and then were given typical new mobile, that requires charging at least every two days, and in practice most people charge every day. Switching to an Electric Vehicle is a similar change, as most people refuel internal combustion cars about once per week, so they need range for an entire week, which charging an Electric Vehicle at home is like charging a phone so enough range for two days would normally be adequate. We have been trained by past habits to need more range do to the refuelling process and the change can create anxiety. There is a real problem for infrequent long trips, and an imagined problem on normal days.

On Balance: Battery Electric

Perfect for every day use, but with question marks for the rarer days kilometres (or miles) travelled with exceed 2/3 of vehicle range- or around 250km (or 150 miles) for long range battery electric cars, and shorter trips for shorter range vehicles.

For a two car family, the case is very clear for one car to be electric. But for singles or one car families, there is a question over refuelling on those long trips.

Hybrids & Plug-In Hybrids

Non-plugin

Non plugin hybrids charge the battery using only enery from the fossil fuel Internal Combustion Engine(ICE). Ideally, the only energy used to charge the battery would otherwise be lost through braking. The ICE generates energy which is used to accelerate the car…and when then needs to slow down the car needs to ‘cancel’ that energy. This energy that must be ‘cancelled’ can be converted to heat by the brakes, or by using a generator as a brake, saved in a battery for reuse. Saving the energy which would otherwise be wasted, just makes sense and all cars will soon do this, so all cars will claim to be at least a ‘hybrid’ in this manner. All except electric vehicles, which also save unwanted energy this same way already. The gain in efficiency depends on how often the brakes might be applied and the generator used as a braking system. If a vehicle needs to frequently accelerates and then decelerates due to traffic, or red lights or other interruptions, then significant energy can be saved for reuse. On a good freeway, this potential ‘wastage’ should be minimal, but in a traffic jam, or with many traffic lights, the potential wastage is significant, so significant energy can be stored and used for future acceleration, reducing fossil fuel use.

But non-plugin hydbrids are still fully fossil fuel powered, with the electrical system simply improving efficiency. As such, this page is not really about these vehicles. They are a step to greater efficiency, but still the only energy source is fossil fuels, as all the electrical energy is generated by braking is recovering some of the energy generated from the fossil fuel by the internal combustion engine.

The case for Plug In Hybrids.

Internal Combustions to best cover long trips: The usage pattern discussed in ‘range’ under ‘the case against battery electric’. A 50km range needed for almost every day, but a much longer range required to cover the rare need for a longer range. The advantage of the plug in hybrid is capablity for the infrequent longer range trips could be 700 or even 1,000 kms, a range not possible with any battery EV as of 2019, where over 400km range is rare, and beyond 500 not available. A further advantage is that refuelling a plug in hybrind on those longer trips is using current well established and high availability refuelling.

Electric for normal driving: The normal driving use case, that is almost every day for most consumers, can entirely be satisfied provided a plug-in hybrid is available with sufficient range for that use case. With vehicles now frequently having 50km range, and the ‘insurance’ of the ICE if the limit is reached, plug ins finally provide the possibility of practical every day electric motoring for many people.

The case against Plug in Hybrids

Limited ‘Pure Electrc Range’: To achieve the optimal result of electric power for days with regular distances travelled, the electric range must provide sufficient distance. In 2019, vehicles with pure electric range of 40-40kms are common, but previously distance were often inadequate. In fact, 50km range, while adequate for some, does not enable this to be viable electric travel for a significant number of others.

Poor ‘Pure Electric’ experience: In practice, the ideal mix of providing the normal trips as pure electric, and reserving the Internal Combustion Engine for long trips is often unattractive because the experience in pure electric mode is too compromised. Consider, for example, the Volvo XC60 T8. 235kW of gasoline power, and 65kW of electric power. Which engine is the priority? How good is the experience when driving in pure electric mode? A comparable pure electric vehicle, the Jaguar I-Pace, has more than 4.5 times the kW (295kW) and almost 3 times the torque of the T8 in pure electric mode. Despite a comparable price, only when the T8 is fully using both engines provide close to a similar experience.

Plug In Hybrid Identity Crisis: Is a plug in hybrid a part-time electric vehicle, or a performance boosted gasoline powered vehicle? Consider the Volvo XC60 T8. Underpowered in pure electric mode, but with sports car acceleration when using both gasoline and electric motors. While no SUV handles fully like a sports car, the cornering of the XC60 T8 is further compromised by the weight of the heavy battery. As a sports car, the T8 simply has a battery that is too large and too heavy for the role as a ‘sports SUV’, yet as a plug in hybrid, although the large battery provides the necessary range, the driving experience encourages use as primarily a gasoline powered car with extra power available from the electric power. The Volvo, and many other plug-in hybrids, are more comfortable as ‘sporty’ (or fast accelerating but heavy) gasoline powered vehicles with electric motors boost performance, rather than being suited to spending most regular commutes in ‘pure electric’ mode.

Poor Range: Given the great range available to conventional gasoline engines,

On Balance: Plug-In Hybrid

Not ranged extened electric vehicles. From online posts and reviews by owners, it is clear some consumers do buy plug in hybrids to use as electric vehicles in day to day usage, but most are not particularly fit for that purpose. Despite promoted electric only ranges, operation in electric only mode is most often disapointing and the engine data almost always reveals the gasoline engine is the primary power source for the vehicle. A complete internal combustion engine, gearbox, exhaust system, radiator and cooling system together with a fossil fuel tank is a lot of hardware to provide range extension.

Hydrogen Hybrid

Hydrogen hybrid, What and Why?

What? A plug in hybrid accepts two types of ‘fuel’, fluid (usually gasoline) and electricty. Now imagine instead a vehicle that accepts both hydrogen and electricity as fuels. Hydrogen requires a tank, much like gasoline, so from a fuel perspective this is similar to a plug in hybrid. However both hydrogen and battery electric cars use the same type of electric motor drive trains, so this vehicle would be a much simpler design. For the design, take a battery electric vehicle, reduce the size of the battery to provide only 50to 80km range, but then add a hydrogen fuel cell in place the larger orginal battery to add — perhaps another 800km of range. Total range of almost 900km (650 miles), yet it could still be lighter than a convential battery electric.

Why? The range could be mostly dictated by hydrogen for the fuel cell, providing the long range with low weight from hydrogen. The limited battery range, as with a plug in hybrid, is easily charged overnight by a home domestic powered charger and provides the range for a normal days drive. Unlike a plug in hybrid, in pure electric mode full power is available, and there is no internal combustion engine, radiator, grearbox and exhaust system acting as ‘dead weight’. The battery has been reduced to between 1/5 to 1/8 the battery size of the battery of a full battery electric car, so there is no super heavy battery capable of 400km range being carried around day after day, just to be ready for the rare day the extra range is needed. Most every days the range required will be 80km or 50km or less, and that is all the weight being carried, even though extended range can be ‘on tap’ through hydrogen. On almost every day this vehicle would be more efficient then either plug in hybrid or pure battery electric, and still have a potential range beyond either.

Hydrogen Hybrid: An answer to range anxiety?

Long Range: Remember that 200x the energy per unit weight! All ‘batteries’, including a fuel cell, are all about chemical reactions. The weight of the ingredients determines the weight of the battery. The ingredients for a hydrogen car are hydrogen and oxygen. In fact 8 parts (by weight) Oxygen and 1 part Hydrogen. So only 1/9 of the ingredients must be carried in the car, as the oxygen can be extracted from air. Plus, that 1/9 happens to be lightest element in the universe. So you can carry a huge range, at a very small weight penalty.

Fast Refuel: Unlike convential batteries where the ingredients are kept in the battery and the charge has to be applied to the battery as a reverse of discharge, filling with hydrogen like simply filling the battery with new ingredients. As fast and as simple as filling any fuel tank. So not only is the range long, the refuelling is fast.

Hydrogen hybrid: Fuel costs / Storage Cost

Fuel cost? Relative fuel cost is usually significant impacted by the fact that more electricity is required as a result of adding extracting and compressing/supercooling the hydrogen. But there are situations where renewal energy might otherwise go to waste, for example, in remote locations not connected to the electricity grid. Where supply is available from the grid, there will be a cost penalty. This cost penalty will be less significant when recharging ‘on trip’ where any charing station must collect revenues, so power will cost more than at home anyway. Plus, savings from not carrying the heavy battery all year should help offset the cost of any increasing in the premium electricity costs when on a long trip. After all, it still should be less expensive than gasoline.

Storage Cost? In any fuelling locations not connected to the grid, or with a connection unable to provide the current required for charging rapidly, electricity must be stored. The good news is hydrogen provides one of the lost possible costs for storing electricity. Every litre of hydrogen effectively is stored electricity, and all you need is tank to store it. Very attractive compared to a megabattery! If you have the ‘tank’ filled from solar or wind, the limit to what can be stored will often be determined by the size of storage.

Hydrogen Hybrid: Refuelling is the elephant in the room

The reason hydrogen power cars in any form are rare is the lack of hydrogen refueling. There are steps planned to address this, and if these plans succeed then the technology should be a winner: at least as a hybrid with battery electric. However, there will still be questions on cost, and there is a need for hydrogen to gain uptake in areas like aviation for any certainty over a refuel network. Weight of fuel is even more important in aviation industry, and if that did take up, aeroports and airstrips alone as refuelling would be sufficient for hybrid hydrogen.

On balance: Hydrogen Hybrid

Note, I am not aware of any hydrogen hybrid and invented the terminolgy myself. Clearly the big question is around Hydrogen is whether a fuelling network can be created. If you can obtain the hydrogen, this is the ultimate. A hydrogen hybrid is more cost effective than hydrogen alone, and would on require a smaller network of refuelling. With battery range covering the vast bulk of kilometres covered by the vehicles at a lower cost than possible with hydrogen, the impact of any price increase over battery is small, only applicable on long trips, and more than offsett by range and lower running costs when running on battery due to the smaller battery. If hydrogen does become available, then this is the best option of those currently being proposed.

Conclusion

Right now, to run electric the best choic pure battery electric vehicle. Plug-in hybrid currently available are lost in an identity crisis, and offer a sub optimal experience unless you plan to use fossil fuel as the main power source. Certainly all hybrids offer fuel savings compared to having the same performance without the hybrid, but the still run on fossil fuel.

Hydrogen could be used together with battery electric in future, given the established recharging network it is going to require a big step. Perhaps there is hydrogen in the future, but it does happen, it will still not make battery electric redundant.

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