Home, Auto Repair Library, Auto Parts, Accessories, Tools, Manuals & Books, Car BLOG, Links, Index
If you drive a car, a truck or a SUV that runs on gasoline or diesel fuel, your engine’s exhaust contains various byproducts of combustion. The two biggest byproducts are carbon dioxide (CO2) and water vapor (H2O). You can’t see CO2 because it is an invisible gas but you can see droplets of condensed water vapor as steam coming out of your tailpipe when your engine is first started on a cold morning.
When gasoline, diesel fuel, alcohol, propane, natural gas, coal, wood or any other hydrocarbon is burned, it combines with oxygen to release thermal energy (heat) as well as CO2, H2O and small amounts of various other chemical byproducts including unburned hydrocarbons (HC), oxides of nitrogen (NOx), carbon monoxide (CO), sulfur dioxide (SO2) and soot or smoke.
CO2 and water vapor are generally considered to be “harmless” byproducts because they are nontoxic and do not cause air pollution or smog like the other byproducts of combustion do. Even so, scientists have ample evidence that CO2 is not exactly harmless because rising levels of CO2 in the atmosphere from burning fossil fuels is causing global warming and climate change. It is a well-established fact that CO2 is a potent greenhouse gas that heats up the atmosphere because of its ability to absorb and retain heat. The planet Venus is a perfect example of what happens when the atmosphere is literally full of CO2. It creates a runaway greenhouse effect that causes global temperatures to soar. The average surface temperature of Venus as measured by various space probes is 867 degrees F, which is hot enough to melt lead.
Things here on earth would never get that bad because out atmosphere is mostly nitrogen (78%), oxygen (21%) and only a small amount of CO2 (0.04%). Although that tiny amount of CO2 doesn’t seem like much, it does have a significant impact on heat retention in the atmosphere.
Whether the CO2 comes from a natural source such as a forest fire or volcano, or from burning gasoline in your car’s engine, it has the same atmospheric effect once it enters the atmosphere. To make matters worse, CO2 hangs around a long, long time (300 to 1,000 years according to NASA) before it is absorbed by the ocean, by plants or converted into limestone by natural processes.
Over time, the amount of CO2 in the atmosphere attributed to motor vehicles and other human activity has been rising (proven fact as monitored by scientists all over the world). CO2 levels have risen 50 percent over the past 200 years, and is now at a level of around 440 parts per million (ppm).
CO2 levels rise and fall with changing seasons as a result of plant growth, but today it is roughly TWICE the average concentration that has been recorded in geologic sediments and ice cores from over the past 800,000 years! So yes, rising CO2 levels is a big concern. It is not some liberal conspiracy theory that has been concocted to banish internal combustion engines and put the fossil fuels industries out of business. It is an existential threat that affects everybody on our planet. If we continue doing business as usual and make no changes to reduce our use of fossil fuels, we’re dooming future generations to a very uncertain existence. The steady rise in average global temperature is well documented, and we are seeing those effects now as record heat waves in some parts of the world, increased forest fires, record rainfalls and flooding, more violent hurricanes and tornadoes, and even droughts. It is creating wild and unpredictable weather changes all around the globe.
Rising levels of manmade CO2 are obviously a major concern these days, but what about H2O as a combustion byproduct of burning fossil fuels? This manmade water (which scientists refer to as “anthropogenic” water) is the exact same water that has been around for billions of years. Water is pretty durable stuff, capable of existing unchanged for literally tens or even hundreds of thousands of years when it is trapped in solid form as ice in a glacier or the polar ice caps.
Water covers about 71 percent of the earth’s surface if you add up all the land covered by oceans, lakes and rivers. All this surface water is being constantly recycled over and over again through the processes of evaporation, condensation and rain. Most rain water runs off and eventually returns to the sea, but some of it is absorbed by plant roots and is broken down by the process of photosynthesis to create glucose (sugar the plants use to grow) and oxygen (which we breathe).
A certain amount of water is also broken down in clouds by electrical activity and lightning. It’s a natural process that tears apart water molecules to create chemically reactive compounds such as ozone (O3), hydroxyl radical (OH) and hydroperoxyl radical (HO2). These chemicals react with other pollutants that may be in the air such as smoke, soot, nitrogen compounds, etc. to actually clean the atmosphere. It’s all a part of nature’s way of recycling and restoring balance.
Water is an essential element in life on earth. We can all agree on that. But is too much water possibly a bad thing? Flooding certainly is, as is a rising sea level that will eventually cover many small ocean islands and flood coastal plains.
World sea levels have been slowly rising since the 1880s (about 8 to 9 inches so far), but the rate of seal level rise is accelerating. As global warming increases the melting of glaciers and polar ice caps, all that runoff water is adding up rather quickly. Various climate models predict sea levels may rise anywhere from a couple of feet to as much as 8 or more feet by 2100. That seems like a long ways off, but keep in mind that much of southern Florida is less than 3 feet above sea level. There’s a lot of expensive real estate in Miami that might be underwater if such a scenario comes true.
Most of the rise in sea levels is not from a growing accumulation of manmade water but from melting glaciers and polar ice caps, so that isn’t the issue with burning fossil fuels. What is the issue is the potential affect additional water vapor from manmade sources may be having on local weather.
Scientists have documented the weather effects jet contrails (condensed water vapor at high altitude) can have on local temperatures and precipitation (some good, some bad). So how might water vapor from automotive exhausts in large urban areas affect the weather?
The amount of water in the atmosphere (which we call humidity) can vary greatly day-to-day depending on location, local weather conditions, time of day, the season and even solar activity. Clouds are the most obvious indicator of water suspended in the atmosphere. Clouds are nothing more than droplets of water vapor condensed around tiny particles of dust. Clouds reflect solar radiation and have a slight cooling effect during daylight hours. But clouds also retain heat and act like a blanket that prevents heat from radiating back out into space (fact: clear nights are cooler than when there is a cloud cover overhead).
Large urban areas with high density development and lots of concrete and parking lots are typically hotter and drier than surrounding rural areas that have open land, lots of vegetation and low density development. So cities do have their own weather effects.
An interesting consequence of this is that heat and moisture rising from the city can impact weather up to several hundred miles downwind from the city’s location. It may cause increased rainfall and flooding when other weather conditions are just right. So it is possible that water vapor from automotive exhausts and other uses of fossil fuels in a city may be having a weather effect.
As it turns out, water vapor is actually a much more potent greenhouse gas than CO2 because water is about 50 percent more efficient at absorbing and trapping heat than CO2. Consequently, a rising level of humidity in the atmosphere can have a really significant impact on temperature and weather The energy held by the water in clouds can react with wind and solar radiation to create storms, sometimes huge ones such as tornadoes and gigantic hurricanes that can cause severe damage. When a hurricane passes over warm ocean water, it picks up strength and can turn into a monster before it hits landfall. And when the atmosphere is super saturated with moisture, it produces rain, sometimes LOTS of rain and flooding.
Based on how weather works and how we are adding millions and billions of gallons of manmade water to the atmosphere by burning enormous amounts of fossil fuels, it’s obvious we are having an impact on the world around us. You can’t blame the changes on natural processes alone.
Burning one gallon of gasoline produces a little over one gallon of water vapor in the exhaust (1.033 gallons to be exact depending on the mix of hydrocarbons in the fuel and its octane rating). Water is formed when hydrogen atoms in the fuel combine with oxygen in a ratio of two-to-one to create H2O.
Now consider the following:
The average number of miles traveled yearly in the U.S. per vehicle was 14,263 in 2023.
The average fuel economy of the U.S. vehicle fleet (all cars, trucks & SUVs) was 26.4 mpg in 2023.
Do the math, and you see that the average vehicle in the U.S. burned about 540 gallons of gasoline in 2023, and produced about 558 gallons of water vapor out the tailpipe.
A key point to keep in mind here is that these 558 gallons of water is newly created manmade water that did not exist on our planet before the fuel was burned. It was created by driving your car. It did not come down from the heavens or seep up out of the bowels of the earth. It just blew out your tailpipe.
The U.S. burns about 378 million gallons of gasoline per day, so we are creating around 390 million gallons of manmade water every day. Multiply that by 365 days per year and you get 142,350,000,000 (142 BILLION) gallons of brand new water that is now part of the earth’s biosphere.
Obviously, American’s are not the only ones who drive cars so we have to consider how much new manmade water is being created by ALL the cars and trucks in the world. In 2023, the world car population reached a record 1.5 BILLION vehicles. Most of the recent growth has come from increased vehicle production and ownership in China, India, Mexico, Brazil and South Africa. New car sales in China were 30 million in 2023, TWICE the number of new cars produced and sold in the U.S.
The U.S. vehicle population accounts for only about one fifth of the world’s vehicle population, so we have to multiply the 142 billion gallons of water produced in the U.S. by five to estimate how much manmade water the entire planet is creating. It turns out to be 710 BILLION gallons!
But that’s not all of the manmade water that is being created. We also have to add in all the water vapor that is being released by residential, commercial, industrial, aviation, shipping and other human activities, which accounts for two-thirds of the total. So multiply the H2O from cars by 3 and we end up with over TWO TRILLION gallons of new manmade water.
Scientists estimate the world’s oceans contain 352 quintillion gallons of water. One quintillion is a million trillions. All those zeros are hard to comprehend, but it tells me the amount of water produced by cars, trucks, SUVs and all the other manmade uses of hydrocarbon fuels is literally a drop in the overall bucket.
Does this mean there’s really nothing to worry about? Is all this new manmade water that is being dumped into the atmosphere daily by human activity having no significant impact on the planet’s weather?
The answer is unknown. There is evidence that suggests it may be affecting local weather and contributing to much of the weird weather we have been experiencing in recent years.
The states with the highest vehicle registrations in the U.S. are California (31 million), Texas (23 million) and Florida (19 million), which happen to be the same states that have been experiencing record rainfalls, flooding and unusually severe storms in recent years. Is there a possible cause and effect relationship here that deserves closer investigation? Maybe there is.
More research is obviously needed to determine if water vapor from vehicles and other human activities is affecting weather, global warming and climate change.
The point of this article is to raise awareness that continuing to use fossil fuels in motor vehicles is affecting our planet, and it will only get worse as the world’s vehicle population (and human population) continue to grow. I’m not pushing any political agenda or promoting wacko conspiracy theories here. I’m just looking at the facts and the reality of how vehicles are affecting the world around us.
Most of the world’s scientific community and forward thinking political leaders have come to the same conclusion that fossil fuels are having multiple negative effects on our planet and that one way to mitigate and maybe even reverse some of the changes that have already occurred is to transition away from fossil fuels to “green” energy and electric vehicles.
EVs don’t burn hydrocarbons so there is no exhaust, no combustion byproducts, no CO2, no water vapor or other pollutants to be concerned about. Of course, this assumes the EV battery is charged with electricity from wind, solar, hydroelectric, geothermal or nuclear power generation. If the electricity comes from a coal or natural gas fired power plant, there’s still combustion byproducts being released into the atmosphere, but less emissions overall because EVs use their energy much more efficiently than internal combustion powered vehicles. ICE vehicles waste nearly two-thirds of the fuel they burn.
The world’s vehicle manufacturers are all investing heavily in the transition to electric cars, trucks and SUVs. It’s not just a domestic trend. It’s a worldwide movement, and sadly one that America is trailing behind instead of leading.
I'm a lifelong ICE guy and have earned much of my living writing about engine rebuilding, diagnosis and repair, plus many high performance articles. I love racing and the rumble of a big V* with a hot cam. But when an obviously superior new technology comes along (EVs I'm talking about), it's time for the internal combustion engine to fade into history and to move forward with a better, more efficient, quieter, cleaner (and faster) means of transportation.
More and more new EV models are being launched and built each year, and EV sales are rising although not as fast as many had hoped because of high prices, battery technology that is still evolving and improving, and a shortfall in public charging infrastructure. I do not yet own an EV, but I likely will in the near future. Within a decade or less, EVs should be outselling ICE vehicles as battery technology advances and prices become more affordable for the masses.
Will transitioning to EVs as a primary means of personal transportation eliminate all of our concerns about CO2 and manmade H20 affecting global warming, climate change and extreme weather events? Nobody knows for sure, but it should reduce our impact on the balance of nature when it comes to the weather.
Related Articles:
Click Here to See More Carley Automotive Technical Articles
