Are there any green alternatives to asphalt in development?

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.

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”

Asphalt is really highly recycled (though I'm sure at a high energy cost), so at least we have that going for us.

I do like the brick roads they often have in places like the Netherlands. Example

Not sure how they compare in environmental impact though.

Trains

Brick.

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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

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.

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.

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.

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.

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 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."

The ground up corpses of the recently deceased.

Solar Roadways has been trying to make it work for a while, but I think they will end up being a project better geared for driveways or parking lots or bicycle highways rather than replacing asphalt roads, just based on the enormous amount of issues they've had in the past in trying to shield and protect the lighting elements.

It could still do a lot of good even in the more limited applications, though, so I'm still hoping for their eventual success, even if it ends up being on a smaller scale than what their initial goal was.