Main Page

Welcome to the explain xkcd wiki!

We have collaboratively explained 6 xkcd comics, and only 2943 (100%) remain. Add yours while there's a chance!

Latest comic

Go to this comic explanation

|< < Prev Comic #2948 (June 19, 2024)

Electric vs Gas

Title text: An idling gas engine may be annoyingly loud, but that's the price you pay for having WAY less torque available at a standstill.

Explanation

This explanation may be incomplete or incorrect: Created by a HYDROGEN INTERNAL COMBUSTION ENGINE RUNNING A GENERATOR. Do NOT delete this tag too soon.

Internal combustion engines (ICE) are the most common technology used to propel motor vehicles. In US vernacular, the most common motor fuel is known as "gasoline", or "gas" for short, leading to these engines being referred to as "gas engines". Gasoline is a product of petroleum refinement, leading to the name "petrol" being used in other dialects. (The word "gasoline" does not actually refer to a gas, but derives from the brand-name fuel "Cazeline" or "Cazelline" sold by a man called John Cassell, and "Petrol" has also been a registered brand name for another business's motor-fuel product.)

Electric motors would seem the more obvious method for propelling a vehicle, and as early as 1885 were an actual form of motor car engine with which the fledgling internal combustion engine had to compete. Despite this early popularity, over most of the 20th century electric motors were sidelined in everyday car design, as supplying the electricity was considered to be impractical for most forms of transportation. Modern forms are rapidly rising in popularity, and now constitute 18% of all global vehicle sales. Randall has long been a strong proponent of electric vehicles.

In this strip, White Hat claims to be comparing the pros and cons of electric motors and gas engines. The joke is that every point he makes goes in favor of electric motors. Despite it being posed as a dilemma, it may be very clear which side of the debate White Hat is promoting. On the other hand, it may indicate that one of the things we might consider a pro in electric motors (the instantaneous power now available, exceeding that of many non-electric engines) he would consider a problem — perhaps more accurately, a problem with the drivers of such vehicles — recklessly using the enhanced capabilities to accelerate to high speeds at all opportunities, whether safe to do so or not.

The strip offers the following points in favor of electric motors:

• "Cleaner and more efficient". Internal combustion engines produce and vent harmful combustion products and toxic chemicals, while electric motors produce no emission byproducts at the point of use. The efficiency of both gas and electric motors vary, but the typical ICE vehicle in the US converts around 25% of available energy into motion, while the typical electric vehicle is in the neighborhood of 80%. It should be noted that all of this refers to the motors only, and ignores how the fuel and electricity are produced, or the wider environmental impact of the vehicle. Even when considering inefficiencies in the source production and transmission and storage and release of energy, battery-driven electric vehicles are generally more efficient than internal combustion propelled vehicles[1].

• "More powerful". Electric motors are able to deliver a lot of power from a small motor if an ample energy supply is available, and can do so 'on demand', often far quicker than a fuel-powered engine that has to put its power through a gearbox in order to service a wide range of road velocities, from standstill to the eventual top speed. Due to battery limitations, short or partial runtime use cases (such as dragsters, hand tools, yard tools, toys and electric scooters) net the most benefit from the small size of a high-powered electric motor.

• "Annoyingly loud". Internal combustion engines, by their nature, produce significant noise. Despite noise attenuation measures such as mufflers, they contribute significantly to urban noise. Properly designed electric motors are nearly silent. In particular, turbo-charger blow-off valves make particular noises that are completely lacking in an all-electric vehicle being driven at a similar performance level. This might legitimately be considered a problem, though, when everyone is used to a rapidly approaching vehicle providing a very noisy warning of its approach. EV makers have sometimes added fake ICE noises to appeal to older drivers, and in the U.S. and some other countries, EVs are required to have warning sounds at low speeds for pedestrian safety.

• "WAY less torque available at standstill". Internal combustion engines need to continually operate within a specific range of rotational speeds, which means that a complex system of transmission gearing is needed to convert this motion into the specific speeds needed at the wheels. When starting from a standstill, this means that torque must be applied to the wheels relatively gradually to avoid stalling the engine. In addition, when a vehicle is standing still, the motor is typically idling at (very) low speed and must be sped up before it produces significant acceleration. Electric motors, in contrast, generally produce their peak torque when at a standstill. This results in electric vehicles having significantly better acceleration and engine responsiveness. Again, this could cause a legitimate problem with drivers changing from ICE to electric motors, because the new cars accelerate more than the driver is used to and provide different feedback. The audible clues of gear changes, whether from automatic or manual systems, are part and parcel of what many people have grown up with and come to rely on in anticipating what might need paying attention to.

The strip offers no points in favor of internal combustion (gas) motors, even those framed as if they were such.

It should be noted that White Hat is deliberately confining his arguments to electric vs gas motors rather than electric or gas-powered vehicles. Doing so ignores the basic reason why internal combustion vehicles have long dominated transportation: hydrocarbon fuels are a very dense and fairly easy to handle form of energy storage. Providing electrical power to a moving vehicle requires either that the vehicle remain in contact with a power line, like a train does, or a high-capacity battery and the ability to recharge that battery in a reasonable amount of time. More popular in the USA is a hybrid system, where a combustion engine provides at least some of the power to an electric motor, which was impractical until comparatively recently. Other methods, such as hydrogen fuel cells (a form of "combustion" that can be used more directly to form electricity), have been proposed, but remain niche, due to various barriers to adoption, or experimental. In the EU, the sale of new ICE cars is banned from 2035 in an effort to move to EVs.

A more comprehensive comparison would include the cons of electric vehicles, including:

• Higher cost of purchase (primarily due to the cost of batteries and, in the USA, now a 100% tariff on Chinese EVs), although partially offset by lower costs of operation
• Long charging times compared to refilling a gas tank (there are some approaches which mitigate this by operating either very high powered chargers or a battery swap model, rather than charging in-car, but these are not widely adopted)
• Relatively limited range ([100-400 miles per charge](https://ev-database.org/compare/electric-vehicle-longest-range) as of 2024)
• Shortened range in hot weather and significantly shortened range in cold weather (although ICE vehicles also have this problem)
• Limited charging infrastructure in some places (although ICE vehicles also have this problem)
• Higher vehicle weight, and resulting higher particulate emissions (from tires and while braking, although recuperation reduces the need for braking)
• Reliance on various mineral and metal extraction industries in the building of batteries
• Issues disposing of/recycling batteries at end of life
• Increased demand on electricity production

Advancing technologies, political policies and economic realities may change how serious these cons are, but they currently remain genuine issues.

Other pros of electric vehicles aren't mentioned

• Lower costs of operation (partially offset by higher costs of purchase)
• Can "fill" them at home or while parked without having to stay with them (partially negates the "long charging times" con)
• Higher reliability
• Significantly lower total particulate emissions
• Lower maintenance and repair costs
• Lower dependence on fossil fuel industry
• Lower carbon footprint

Future economic and political policies may make fueling and maintenance of gas powered personal vehicles an issue. If in 10 years 100% of vehicles sold are electric, then after the average 12 year vehicle lifespan of fuel vehicles has ended it may be that legacy fuel stations are harder to find (and recharging stations easier) in comparison to the other type. At the 20-year mark, most gasoline-fueled cars will be gone and the economic value of providing ubiquitously available fuel to a dwindling number of cherished hold-out 'classic' vehicles will have forced the supply chains to pivot. Maintenance for such cars may become an art of the past and finding a specialized mechanic may be necessary. (As, until recently, it would have been difficult to find an independent EV-qualified mechanic.)

Transcript

[White Hat, with his palm raised, is talking to Cueball.]

White Hat: Electric motors and gas engines each have their pros and cons.

White Hat: On one hand, electric motors are cleaner and more efficient. On the other hand, electric motors are more powerful.

White Hat: So it's hard to say which is better overall.

Is this out of date? .

New here?

Last 7 days (Top 10)

Rank Score Pages Changes Username 1 21 18 20 TheusafBOT 2 16 11 17 Erik Angus Nelson 3 13 7 16 Psychoticpotato 4 10 6 11 Asdf 5 8 3 10 ProphetZarquon 6 7 3 7 Elektrizikekswerk 7 7 3 7 Beanie 8 7 4 6 Maplestrip 9 6 4 5 Usb-rave 10 5 1 5 NiceGuy1

Lots of people contribute to make this wiki a success. Many of the recent contributors, listed above, have just joined. You can do it too! Create your account here.

You can read a brief introduction about this wiki at explain xkcd. Feel free to sign up for an account and contribute to the wiki! We need explanations for comics, characters, themes, memes and everything in between. If it is referenced in an xkcd web comic, it should be here.

• If you're new to wikis like this, take a look at these help pages describing how to navigate the wiki, and how to edit pages.

• Discussion about various parts of the wiki is going on at Explain XKCD:Community portal. Share your 2¢!

• List of all comics contains a complete table of all xkcd comics so far and the corresponding explanations. The missing explanations are listed here. Feel free to help out by creating them! Here's how.

Rules

Don't be a jerk. There are a lot of comics that don't have set in stone explanations; feel free to put multiple interpretations in the wiki page for each comic.

If you want to talk about a specific comic, use its discussion page.

Please only submit material directly related to —and helping everyone better understand— xkcd... and of course only submit material that can legally be posted (and freely edited.) Off-topic or other inappropriate content is subject to removal or modification at admin discretion, and users who repeatedly post such content will be blocked.

If you need assistance from an admin, post a message to the Admin requests board.