[mrpopo]

Mandatory reminder that hydrogen as fuel for cars is an incredible waste of primary energy and will be for a long time.

A petrol car engine is inefficient due to constraints (small + no cooling source other than air).

An electric engine + battery is extremely efficient (the "downside" is you can't use the wasted energy to heat up the car in winter like an ICE).

An electric engine + hydrogen fuel tank brings back inefficiency, and you can't even reuse that wasted energy because most of this waste is electrolysis.

[samtho]

On the other hand, you can refill a pressurized hydrogen tank in seconds. Electricity itself is merely a mode of energy transmission. Energy storage has and will continue to be a huge innovation area as the current means of battery charging are either slow or low capacity. We’re getting really good at getting energy from the sun, and excess energy not consumed is wasted, so why not make hydrogen? Heck, why not have fuel stations in the middle of nowhere have a well (for water extraction) and an array of solar panels so the station can produce its own product to sell?

I can see a future where you can opt for a hydrogen fuel cell EV rather than a battery powered one. Efficiently using the hydrogen will be a non-issue if we are able to trivially produce a vast abundance of it.

It’s hard to say that an EV is just as good (for the consumer) as an ICE engine if I am taking a road trip and one of many fill-ups makes me wait for hours. There are these uncommon cars that opponents usually cite and are sometimes unfairly dismissed. I say this because we can and will make EV technology better and cheaper and I’m willing to bet money that hydrogen fuel cell in lieu of batteries will become a thing.

[mrpopo]

Solar power is 1.68% of the USA's primary energy mix in 2021. Wind is 3.89%, about 2.5% more than a decade ago, and the trend is not accelerating that fast.

It is not even 3 decades to 2050, which is the USA's target date for net zero carbon, so with conservative estimates primary energy from wind should increase by at least 10% per decade, so 4 times faster than last decade.

Where is the vast abundance of renewable energy that you are talking about? Now is not the time for deploying another massively wasteful technology just because some people want to go on road trips without taking a 30 min break (a recent EV fast charge does not take hours) every few hours.

[samtho]

I don’t think those extrapolations are totally fair. You’re assuming today’s technology is frozen, inflexible, and adoption is going to linear. If we have learned anything from the last decade it is that adoption curves are getting steeper.

If you recall from my original post, I said nothing about that hypothetical, abundant hydrogen being born from any particular source, but I did have solar in mind specifically. I personally think solar cells and panel arrays will get more efficient at producing power that we will eventually have a global excess. If we have grids producing renewable electricity when conditions allow, they can redirect some of the excess energy and use electrolysis to produce hydrogen creating energy reserves for when the power source is not available to them.

Hydrogen is still not super efficient because we have not even scratched the surface of optimizing it’s consumption. If we had concerted efforts towards that goal, we can get it to work for us in ways we never thought possible. I don’t think lugging around large batteries is the future, rather our fuel storage needs will be met by hydrogen tanks.

[mrpopo]

I'm not assuming linear adoption. I explicitly said that even if adoption was FOUR TIMES faster than now, the amount of renewable energy would barely reach the same amount of primary energy as we use now by 2050.

This is a optimistic scenario. Current trend is mostly linear. See:

Wind power generation, world: https://ourworldindata.org/grapher/wind-generation?tab=chart...

Solar power generation, world: https://ourworldindata.org/grapher/solar-energy-consumption?...

You can choose linear/log, it doesn't look exponential to me.

Add to this the fact that primary energy generation is increasing all over the world, so the share of renewables is increasing even less.

The target is 2050. There is no R&D that will get rid of electrolysis and Carnot cycles by then. Maybe by the end of the century if you want. But for the next 30 years, batteries will be in the lead.

[saveferris]

Some updated figures through 2021 Solar = 2.8% Wind = 9.2%

Total renewables = 20.1%, that includes hydro which may not be as renewable as we thought.

Just had this discussion but relative to why not re-invest in nuclear so we looked up the amount of nuclear energy (~20%).

Not sure if we are looking at different sources, they are counted differently, etc.

Source for this is; https://www.eia.gov/tools/faqs/faq.php?id=427&t=3

[mrpopo]

Your source is counting the share of electricity generation. My source[0] is counting the share of primary energy; including fuel, heating, etc. I believe the latter is more relevant for the current discussion (CO2 emissions and cars). Electricity is not even half of our primary energy use.

[0] https://ourworldindata.org/renewable-energy

[llampx]

> We’re getting really good at getting energy from the sun, and excess energy not consumed is wasted, so why not make hydrogen? Heck, why not have fuel stations in the middle of nowhere have a well (for water extraction) and an array of solar panels so the station can produce its own product to sell?

We are nowhere near being able to satisfy 100% of our energy demand with solar or even a renewables mix, except for a unicorn scenario in which we have high winds and a sunny sky at the same time. On top of that, it is extremely wasteful to use that energy to produce hydrogen and then pipe it around, compared to storing it in batteries - either portable ones like in cars or bigger house or grid-sized ones.

If we have excess solar energy, it would be great to make recharging your car free at that time, although I know that's a pipe dream due to the profit motive.

[hakfoo]

I always figured the solution was a cantenary or third rail style system on major highways.

The EV trickle-charges and uses direct grid current while driving in between cities, and then a 200km range at the endpoint of the journey is more than ample.

[tedk-42]

You think you have two good points (refill time + H2 generation from water) but really you have nothing.

Hydrogen might fill a gap to replace large vehicles like buses or trucks but not passenger vehicles.

[samtho]

Those are great points, actually and your comment provides so little detail that I begin to question the intentions behind it.

We have yet to design many vehicles around a hydrogen fuel cell and we have yet to really realize it’s full potential as a power source, dismissing it on these grounds is simply short-signed thinking.

We can extract this resource from a very abundant resource, water, which is huge. With only energy (from the grid or a micro-grid) and water as inputs, you can produce a substance that is able to store energy for later use who’s only byproduct is water.