Asphalt used on road surfaces are byproducts from fossil fuel. With the ultimate goal of eliminating the use of fossil fuel to combat climate change, are there any good alternatives for road surfaces? I don’t think I’ve ever heard of a viable replacement of asphalt in the works, or even a plan to replace it in any environmental discussions before. At least, not enough for me to notice.
Extented question would be: what are some products derived from fossil fuel that are used in everyday life, but still lack viable alternatives you don’t see enough discussions about?
Bioasphalts can be made from all sorts of non-petroleun renewable resources, including food wastes and sewerage effluent: https://en.m.wikipedia.org/wiki/Bioasphalt
I think the main challenge now will be determining the ideal mix of ingredients that best suit the purpose of the asphalt.
Good to know! Thanks!
Also another factor is heavy vehicles. I don’t have the article or video, but I remember hearing that a majority of road damage comes from heavy vehicles. I believe the video was also comparing roads to Rome roads where it wasn’t that they were built better (although volcanic ash did help) it’s that horses and people are way less heavy than the 3,000+lb vehicles we have going almost 24/7.
Less road damage would mean less containments/pollution and less need for repair. So the future might be seeing more public transit and more rail transit for materials/products which would mean wherever we need to add more road or re do sections we would replace it with the greener option or potential normal asphalt since it wouldn’t need to be touched for another 20,30,40+ years.
that a majority of road damage comes from heavy vehicles
Specifically, wear and tear on the road surface scales with the fourth power of vehicle weight.
As a worked example, this means that if we compare a 3-ton cargo van and a 1½-ton sedan, the cargo van weighs twice as much as the sedan, but it does sixteen times as much damage to the road.
Axle load, actually. In theory a 1.5-ton car with two axles and a 3-ton truck with four equally loaded axles would cause the same amount of damage. A 1-ton unicycle would cause more damage than the truck.
Note, though, that this is a rule of thumb. A 50-ton tank is still a 50-ton tank even if you manage to make it have fifty tiny axles. But for fairly average motor vehicles under fairly average conditions it’s close enough to be useful for planning.
As with all equations in civil engineering, it’s not really derived from physics so much as it’s the curve that best fits the data.
It’s kind of interesting in that way, because it’s an implicit declaration that when shit gets really heavy (pun intended), we trust empirical observations more than we trust our own theories of how things work.
I think it’s a great example of coming back to the roots of science in measurement, as a practical humility we must take seriously because everything civil engineers do is high stakes.
Surely that’s damage-per-axle? So it’d be two 1.5-ton cars to match the trucks 4 axles
It could be, but I wouldn’t assume that it is.
I remember when calculating bridge wear, we were discussing the truck arriving on the bridge in terms of impact. It could be the damage somehow comes mostly from the first wheels to encounter the material.
Wow, it makes sense but definitely not good at all
Climate change isn’t caused by just using fossil fuels to make a product, it’s caused by burning fossil fuels releasing greenhouse gasses, (primarily carbon dioxide and methane), into the environment.
Asphalt is a problematic material, but not so much because it’s made from oil. It’s problematic because we burn fossil fuels to harvest the raw crude and to generate the energy needed to refine crude into asphalt. The carbon in the asphalt itself remains sequestered there and doesn’t contribute to the greenhouse effect as long as it isn’t burned later.
If we figured out how to extract crude and generate the vast amount of energy needed to manufacture asphalt without actually burning fossil fuels we’d eliminate the vast majority of asphalt’s impact on climate change.
In fact it’s been shown in a lab that it’s possible to make asphalt from CO2. It’s currently cost prohibitive to do so, but in theory asphalt could be part of the solution to climate change.
Now Asphalt does have other environmental issues, like leaching toxic chemicals into the soil and water table and the fact that it’s usually black which absorbs more the sun’s radiation than almost anything else which would reflect more of the sun’s energy back out into space. But those problems aren’t necessarily solved by using non-petroleum based bioasphault, nor are they unsolvable with bitumen based asphalt.
About 20% of a barrel of oil gets made into products like plastics or foam, that’s not what’s causing climate change. What causing climate change is the 80% that gets refined and burned for cheep energy. So it’s less “Just stop oil” and more “Just stop burning oil”
That’s not to mention the reusability of asphalt:
Regarding the circular economy, the data from reporting countries showed that in such countries, 72% of the reclaimed asphalt available for the industry was re-used, 25% recycled and only 3% used on unknown applications or put to landfill.
Thank you for the very detailed answer!
Asphalt is a problematic material, but not so much because it’s made from oil. It’s problematic because we burn fossil fuels to harvest the raw crude and to generate the energy needed to refine crude into asphalt. The carbon in the asphalt itself remains sequestered there and doesn’t contribute to the greenhouse effect as long as it isn’t burned later.
Not to mention the lighter fractions will include things like gasoline, and once you have gasoline it’s oh-so-tempting to burn it.
Honestly I doubt the emissions just from heating it in a fractionating tower are all that significant themselves, even if they’re not using renewables to do it.
Asphalt is really highly recycled (though I’m sure at a high energy cost), so at least we have that going for us.
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It currently takes about 3 to 6 cubic meters of gas to make 1 ton of asphalt. It doesn’t really matter if that’s new or recycled, and doesn’t include mining and transporting the materials.
I do like the brick roads they often have in places like the Netherlands. Example
Not sure how they compare in environmental impact though.
Aren’t brick roads bumpy to drive on? It may be fine to put in housing areas where cars drive slow normally, but I imagine it would be a pain in the ass (literally, lol) and dangerous to drive on on high speed roads.
Sure, you wouldn’t put them on highways. But I’d like to have less of those anyway. They’re decent for cycling or driving at lower speeds.
dunno if I’d call it decent. bumps will wear out suspension components prematurely, meaning they’ll have to be replaced more often. so more metal and rubber being produced. is it enough to make brick not worth it? idk. also worth noting that asphalt is far grippier than brick. more grip = safer
I think you really overestimate the bumpiness of those kind of roads. They’re not like medieval cobbleroads.
We have all kinds in my city: Medieval cobblestone, brick roads and asphalt. As a cyclist I have to tell you that I hate all kinds of brick roads that I have encountered. Even when they’re not the horrible middle age version, they will often get deformed by roots or depression of the ground quite rapidly, making them even more bumpy. For this reason I think, I saw in Sweden in an otherwise bricky city center that they had a narrow asphalt lane on the side of the road for cyclists. I was just amazed that someone would spend that much thought into what’s great for cyclists. As a cyclist I really love asphalt :D
Let’s be real here. Asphalt is the result of tens of thousands of years of human decision making, all of it heavily invested in finding the best solution to each problem.
they will often get deformed by roots or depression of the ground quite rapidly
That’s true, but more of a maintenance issue IMO. Brick roads do have the advantage that workers can just take some of the bricks out, fix whatever is wrong underneath and put the same bricks back on. Can’t really do that with asphalt, which will eventually deform as well.
Asphalt is almost a liquid when it’s hot. That’s a significant advantage in application.
I think you underestimate how small differences have large results when we’re talking about nationwide or population-wide issues. If there are a million cars on the road and this change makes suspensions wear 5% faster, then every X years (however long it would usually take for them to wear) there are an extra 50,000 cars needing replacements. That’s not an insignificant amount. Scale that up to larger countries that have tens or hundreds of millions of cars and the result gets even larger.
Small differences make large impacts. 1.5°C average global warming is having disastrous effects on the environment and our capacity to thrive. COVID-19 has a Case Fatality Rate of around 1% (depending on country) and it has caused nearly 7 million deaths - more than the amount of Jewish people murdered in the Holocaust and similar to the Holodomor.
Holocaust total was 12 million, of which 6 million were Jews.
Cheers for the correction - I’ve edited my comment.
I actually know from watching Formula E, that in order to make their indoor/outdoor track in an exhibition center in London race viable, and would still be able to operate normally after the race, they developed a way to add grip on concrete floors without the use of asphalt.
Article link
YouTube video from Chain Bear on how they made the trackEdit: Link format
Bumpier = slower = safer.
Slower = driving less distance = less wear and tear.
how is slower less distance
Time is a limited resource
Consider the fact that you’re unlikely to make a trip to the other side of the world if it weren’t for the fact that airplanes exist and they cover the distance very fast.
Higher speeds enable different trips to happen - the speed changes the types and distances of transportation that happen.
Slower = less transportation happening
Cars are the least efficient means of transporting people and make all other means of transporting less efficient. Less cars = more transportation happening.
Not if people need to go to every point on the map, throughout the whole road grid.
But I think we can consolidate vehicles a bit.
Something like electric bikes or segways or scooters for the last mile helps cover the entire grid.
And we could have double the number of buses, maybe with demand-based scaling of bus lines (no doubt they already do this but I bet it’s on the scale of months instead of hours).
But those other forms of transport don’t provide privacy, and we really like the privacy of a car.
The turbo lift from star trek is a cool idea. Just a room you stand in that takes you wherever. That provides some privacy.
I think more fundamental than the logistical aspects of it, the main hurdle is that sense of owning the space you’re traveling in. In my car I’ve got a thousand little tweaks I’ve made.
Maybe each person could have a vehicle configuration that gets loaded up into the generic shared vehicles, so when they get in it feels like theirs, has all the same things ready.
…No they are very smooth. I think you are thinking of cobblestones.
Hmm, I may have. I admit I have never driven on brick roads before (cobblestone roads yes), so more input on people’s experience and long term observations with these would be great.
Do you think it’s viable in situations like high speed driving? Other potential problems?
Netherlands and Australia use brick in places where we want cars to slow down. Drivers automatically slow their speeds on brick roads. They’re fine to cycle on.
Drivers automatically slow their speeds on brick roads.
Why? Is it not smooth enough to drive fast on?
There’s more rumbling, which makes it feel faster.
That just means it feels uncomfortable and dangerous to drive fast on because it rumbles more, so they slow down.
which makes it feel faster.
I don’t think that’s how it works…
Cars should be banned.
Trains
I mean, I’m all for more public transportation (seriously, wtf America?). But in reality, there is still a need for public roads for things like buses in places where subway stations aren’t viable, and also for logistics (construction materials, mail, Amazon deliveries, your Uber eats, etc.)
don’t forget emergency services
Right, that’s pretty important too!
what about buses? or do we build trainstations all over the cities?
Look at a tram station map of the Melbourne metro area.
Look at railway maps in Tokyo
Or if you are too lazy to search, https://youtu.be/3NfUAO_KjQA
Here is an alternative Piped link(s):
https://piped.video/3NfUAO_KjQA
Piped is a privacy-respecting open-source alternative frontend to YouTube.
I’m open-source; check me out at GitHub.
You forget that many people live in areas where passenger rail infrastructure is not economically (or practically) viable. I, for one, pity the grain truck that has to drive over an unpaved road.
Wooden cart.
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What about brick?
While it’s not a full replacement the raw materials making up the road surface can be reduced. Here’s an example where books were recycled into the road surface - http://news.bbc.co.uk/1/hi/england/west_midlands/3330245.stm
Brick.
Yellow brick
What ruins the asphalt is the weight of vehicles, and in car-free places, you can see 30+ year old asphalt without potholes or cracks with only minor damage or repairs. If it weren’t for the sun making the asphalt pale, you wouldn’t know it isn’t a recently paved street.
By reducing the number of cars in cities and towns in favour of bicycles and rail, and putting stricter restrictions on the weight of the vehicles, we can make asphalt last WAY longer.
Also, some modern asphalts are more durable than older ones, but I don’t know the specifics.
If we eliminate the use of fossil fuel to combat climate change, our agricultural output will drop enormously and a significant fraction of humanity will starve to death.
I think if you‘re driven to find non-fossil road pavement strategies, you should refocus your efforts on finding non-fossil sources of nitrogen for fertilizer.
Food is way more fundamental than roads, and it’s far more heavily reliant on fossil fuels.
Well this thread is a discussion on alternatives and what you think are not talked about enough, so thanks for informing about fertilizers. I certainly didn’t know that they were also reliant on fossil fuel.
Your logic doesn’t make sense. Reducing the use of fossil fuels in other things leaves more for use of growing food.
You mean the atmosphere which is nitrogen rich?
No, they mean the Haber process that requires energy-intensive (can mass-solar do it?) hydrogen to convert nitrogen back into ammonia.
This is all do able without fossil fuels. I don’t understand the atmosphere and water is all you need as electrolysis can formulate hydrogen. Ignoring the catalysts and materials for electrolysis it still only requires 2 things to go through the chemical processes. Do not take lobbying and the fact that this world relies on capitalism to continue to exist to make something like this near impossible. You wouldn’t ever need fossil fuels for this and I ignore energy requirements because of something I refuse to talk about.
It’s about return on energy. Fossil fuels return 20x what you invest it’s essentially free energy.
(edit: roughly, this translates to how many people are free to do things with the work of one, if every person lives alone, it’s 1, if each person has a personal slave/robot, it’s around 2, we want to stay well above 2. Modern society has 19 people doing all sorts of non-survival things for each one farming and collecting resources because fossil is so “cheap”)
Renewables can reach 5-10 at best, which is not so bad (medieval was around 1.3, pre-industrial with slavery was around 1.8), so you can do it, but it will have to reshape society, which will be fine, if we know what we’re doing or can at least imagine what we are aiming for to avoid disappointment. It’s hard to be utopian going backwards.
This whole debate started with carbon footprints and carbon pricong, because I believe that creating a market can help the less virtuous among us to use their greed to help solve the problem of public consent in a consumerist society without devolving into a dictatorship.
But yea, let’s aim for that energy return of say… 7 and try to imagine what such a society would look like. A return to slower shipping by sail again…more solar boilers for all hot water…solar desalination…peak-solar hydrogen for fertilizers and airplanes…more compact cities with mass transit and bikes, lots of working from home, more fixing things DIY…a return from cities to the countryside and decentralisation would help, but only if those communities were more self-sustained and local, with 2x more power to farming, mining and wind/solar communities (meaning potentially smaller countries)…now I could describe all the potential setbacks of all of those points, but I won’t, because this is solarpunk and we need more imagining of what things are going to be like when we succeed…not so much the year 500 :)
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Modern farm fertilizers are all made with ammonia which is produced with natural gas. Apparently Yara,a Norwegian company, is trying to replace the fossil fuel with solar power. Source
Of course you could also use manure or compost as fertilizer, but only some of the few small farmers would probably be willing to since it is harder and therefore more costly.
Hmm. Well, the obvious choice would be some kind of tar. Someone mentioned that oil extraction is not as bad if you don’t burn it, too. What about a plastic blend?
Extended question: One thing I think of is all the various chemical building blocks that go into synthetic things, like drugs. As I understand it, right now we pull up crude, and then repeatedly process it until we’ve split it into 1000s of individual component molecules. Pick a chemical, go to the “production” section of the Wikipedia, click on a component and repeat; you’ll probably find one.
There’s approaches to making individual building blocks green ways, but I don’t think there’s a fallback for cases where a specific commodity chemical has no alternative. What we really need is a way to make a similar blend of things from pyrolysis of biomass. I assume somebody is working on it.
Roads wear. Plastic dust getting spread everywhere is probably a bad thing.
That’s true, but AFAIK asphalt roads don’t tend to produce a fine dust (rather, the tires and mufflers do), so there should be some kind of plastic resin that would wear a similar way.
Then we’ve got big chunks of plastic everywhere.
Trouble is that kind of gradual wear pretty much guarantees the material is coming off in tiny chunks that are basically dust.
Hmm. Usually when I see roads break, it’s more of a disintegration into chunks situation. I really though I watched a video where they vacuumed up dust from alongside a road.
If microplastics are going to be made, that is kind of an issue. Maybe it’s still worth it, or maybe we have to pick an alternative. I guess worst case we could just go to all gravel roads, and it would be slow but you would get there.
That’s a great solution actually, you should de-emphasize cars and put in more trains and infrastructure for local individualized personal vehicles like bikes, ebikes, electric scooters, and even pedestrians.
Aren’t bike paths usually asphalt too? They definitely are where I live.
Rail would work I guess, and mass transit is better than personal cars for any number of reasons, but we’d have to put in a lot of rail and abandon all the significant road infrastructure built up. I’ve mostly stanned buses in the past for that reason.
They can be anything, even asphalt. Concrete, gravel, dirt.
Bikes won’t wear asphalt or anything else as fast as a high speed multi ton vehicle will though.
Kind of a brain dead question. We have much bigger sources of pollution and Asphalt is heavily recycled. We don’t have to replace everything that uses oil, just the heaviest offenders.
The ground up corpses of the recently deceased.
The green alternative to Asphalt existed before Asphalt in the form of Rail Roads. “Green Asphalt” also exists and is currently used for walking trails and biking trails, though it consists of recycled plastic and rubber, so technically it isn’t “asphalt.”
