[rbanffy]

Considering the advances of renewables, both solar and in/off-shore wind, do we really need fusion?

Most of the issues with current fission are political ("spent" fuel can be reprocessed) and economic (these beasts are insanely expensive to build and operate safely) and we haven't even touched MSR's and Thorium. I get fusion would be beautiful, but it has its problems too (heavy neutron bombardment will eventually turn the reactor into a pile of hot nuclear waste - or, at best, MSR fuel) and we may need to face the simple fact our technology isn't up to that challenge just yet.

Although stellarators may offer some shortcuts.

Maybe we'll need fusion for multi-generation starships supposed to operate for many centuries on a closed loop system, but that need seems a bit too far into the future for us to concern ourselves too much with it. Solar should be fine up to Mars and compact fission should be enough up to the Oort cloud.

[lmm]

Renewables can't provide power where it's needed, and largely can't provide reliable baseline power (hydroelectric being the exception, but it causes huge environmental damage in terms of both direct flooding and disruption to downstream ecosystems).

Fission could power us for 100-200 years at current consumption rates - substantially less if consumption continues to grow. It's not time to panic yet, but we can't afford not to be doing fusion research.

[rbanffy]

> can't provide power where it's needed

I grew up with energy generated by a mix of hydro from 800km away and nuclear from 200km. An off-shore wind farm could be built anywhere between 100 and 250km from my city. In-shore wind, if distributed and connected, can provide a lot of reliable with little need for constant hydro or nuclear.

Also, hydro can be rather helpful in other aspects - it can be a store of drinking water, fisheries and agriculture. The environmental impact is, of course, huge, buy far more benign than the current fashion of fossils. Plus, if you are really clever, you can use it to host carbon-fixating algae you can bury to remove a lot of carbon from the atmosphere.

Mind you that fission's environmental impact is not restricted to those rare occasions when everything goes bad and the reactor melts down. Mining for fissiles is not exactly environment friendly.

And while local photovoltaic may have some nasty industrial processes involved, solar-thermal doesn't. It also provides a nice and smooth generation pattern that can cover for baseline generation.

[lmm]

> I grew up with energy generated by a mix of hydro from 800km away and nuclear from 200km.

Impressive, but those grids aren't cheap, and their maintenance is only getting more expensive with modern safety standards and labour costs.

> Also, hydro can be rather helpful in other aspects - it can be a store of drinking water, fisheries and agriculture. The environmental impact is, of course, huge, buy far more benign than the current fashion of fossils.

Anything but coal is progress, sure. But hydro is still damaging enough that it's well worth replacing.

> Mind you that fission's environmental impact is not restricted to those rare occasions when everything goes bad and the reactor melts down. Mining for fissiles is not exactly environment friendly.

The fuel density of fissiles is so high that that's not really an issue though - the amount of fuel mining needed is tiny.

> And while local photovoltaic may have some nasty industrial processes involved, solar-thermal doesn't. It also provides a nice and smooth generation pattern that can cover for baseline generation.

Solar-thermal has potential, but it still has some time/storage issues (yes it doesn't go to zero immediately at dusk, but it's not entirely aligned with demand either, and e.g. seasons are a big issue further from the equator) and location issues.

Ultimately while conventional renewables will be part of the mix - maybe a big part - it's hard to imagine we won't have cases where we need reliable, consistent power in a specific arbitrary location, and nuclear is really the only viable clean power source that can offer that. Maybe storage tech will improve to the point where that's no longer the case, but we can't rely on that - at least, not the extent of closing off nuclear research. The cost of the likes of ITER is a drop in the bucket compared to the world's total energy expenditure.

[graphitezepp]

Not to sound like a fossil shill, but I want to agree with "anything but coal is progress" and suggest that natural gas, done sufficiently cleanly and only for demand curve smoothing, could be part of a 'good enough' solution in the near future.

[resf]

Hydroelectric power, like geothermal, is only applicable if the geography permits it. It is also a potential WMD, so you'd better hope the area where you are building your dam is either not near a population center or is (geo)politically stable.

[XorNot]

Fission, developed, could power us for another 10,000 years if we actually wanted it to. We simply haven't been building up the industrial base to make that possible.

[atemerev]

If we want electric cars (and stop burning fuel in general), we need a lot of cheap electricity (like, 100x more generation than today, 10x cheaper). Photovoltaics is not environmentally friendly. Wind power is not scalable. Only next-gen nuclear and fusion fit the bill.

That said, ITER is not a good approach. Way too expensive, not scalable. It is good as a research project, but we need scalable and cheaper solutions.

[rbanffy]

> 100x more generation than today, 10x cheaper

Or we can rethink our use of cars. I drive one about once per week. The rest of my transportation needs are neatly provided by electric light rail.

We can also tax fossil-burning cars and their fuels according to their environment impact (like "we'll be all dead in a century"). That alone would make electric cars a lot more attractive.

About that, for most of my adult life my cars ran on sugarcane ethanol, which has a pretty close to zero carbon footptint. Plus, if the refining ops were more efficient and didn't burn the refuge to power the operation, it'd have a substantial negative carbon footprint.

[sergiosgc]

The problem with the "saving energy" argument is that it goes against our behaviour in all of recorded History. Mankind has always used more and more energy, and that use of more energy is entirely justified, as it has given us increasing quality of life. Quality of life translates to more than extra comfort. It means new purposes, new goals, new horizons.

If, apart from civilization de-evolution, we never lowered per-capita energy consumption in ~10k years, I have very little faith we can do it now.

[candiodari]

> Or we can rethink our use of cars. I drive one about once per week. The rest of my transportation needs are neatly provided by electric light rail.

How do you deal with doing groceries ? I have to do groceries for 5 people, have to actually cook for them about 14x a week, at, let's say, 150gr of food per person per meal, at 50% waste to allow for actual cooking, so let's say 150gr * 14 * (1/(1-50%))= 5 kilogram, plus stuff to drink. Humans drink about 1.5 liter per day. So all in all, I need the ability to carry some 25-40kg easily. How do I do that using light rail ?

Note: going twice, by itself, increases the cost of groceries due to economies of scale. Going 5 times increases it by a lot, ignoring the lost time. Also, let's not pretend 12x1.5 liter bottles are easy to carry on light rail, even if it's just that and nothing else.

Also light rail, at least in Sydney and London (ie. the metro), only connects places that are ridiculously expensive to rent, and to top that off, light rail is only a little cheaper than a car compared to using a car by myself. With 5 people, they are ridiculously more expensive than using a car. Compared to using a nice secondhand car and traveling 30 times a week (20 of which are simply dropping the kids off at school), the price difference is so high that we cannot discuss using light rail for this.

So how can you claim that this is a solution ? When you're 20 and alone, perhaps. When you have a family, the financial difference is off the scale.

Come to think of it, once I turn 60 or so, is this still your suggestion ? Because then it'll be physically impossible for me to do it at all without a car, just for 2 people.

Personally, I think public transport is effectively a failure. The only function it has is to allow rich middle classers to travel in for their job from the suburbs, taking the car for part of the way. Aside from that it's useful for going out and the like, but it cannot reasonably be a primary mode of transportation.

If it were up to me, I'd tear down public transport entirely and replace it with "uber rail cars". Replace all tracks with normal road, reserved for a government-run fast automated-cars-only network that get called on request using an app, with ride sharing. As soon as possible, make that a network for automated call cars that can actually drive to supermarkets, jobs, ... and use the extensive right of way that we have on rail to have essentially a better highway system. No more stations. No more horrible overcrowded-and-ill-ventilated-and-source-of-countless-infections trains (guess what industry I work in).

> sugarcane ethanol, which has a pretty close to zero carbon footptint.

It also has a 1.05 or so ROEI (or, more likely, <1, when you count full cycle) and is a gimmick. We can probably support a 1905 economy on it. We cannot support the current economy on it.

[rbanffy]

> How do I do that using light rail?

Doing groceries is one of the reasons I still have a car.

> Also, let's not pretend 12x1.5 liter bottles are easy to carry on light rail

Water is transported in pipes. This reduces my need to transport beverages substantially.

> I think public transport is effectively a failure

Most Europeans would disagree.

> It also has a 1.05 or so ROEI (or, more likely, <1, when you count full cycle)

Where did you get that number? Also keep in mind ethanol manufacturing from biomass can probably be very optimized. Sugarcane is just one case that yielded an enormous success in Brazil.

[candiodari]

> Water is transported in pipes. This reduces my need to transport beverages substantially.

They even come with free lead. Also they're government-owned, almost guaranteeing that if these pipes cause health issues (as they have in numerous examples, like Flint, Michigan) you won't get any restitution.

> Most Europeans would disagree.

I have lived in Europe. No they won't. Well, if you put it in those exact terms they might.

But the question asked here: "can public transport replace a car for you ?" would get a very strong "no" from most Europeans.

[aninhumer]

>How do you deal with doing groceries ?

Home delivery. It's far more efficient to have a single van going to a bunch of houses than to have a bunch of people take individual cars to the store and back. Supermarket delivery in the UK is already cheap and convenient, I don't see why it couldn't be similarly good elsewhere.

>Also light rail [...] only connects places that are ridiculously expensive to rent

I think that's largely a symptom of housing shortages in general. Decent public transport makes a property effectively equivalent to one closer to job centres, so it becomes more expensive. Build enough housing and that becomes less of a problem.

>If it were up to me, I'd tear down public transport entirely and replace it with "uber rail cars".

I definitely see the potential of self-driving taxis for public transport, but I don't see why you want to completely replace existing efficient infrastructure. Rather I think their role in future will be to provide last-mile connectivity for efficient public transport links. That way you still get the door-to-door transport, but with a more efficient backbone network.

[bewo001]

In the days before general car ownership, you had small shops in walking distance. They were no longer competitive once shopping centers near the highway could shift the cost of delivery to their car-owning customers.

[candiodari]

It was mostly employment costs and logistics cost (one big store is much cheaper than lots of small ones).

So sorry, but this option and home delivery too come at a significantly higher cost to me (about 2x for this one, about 1.3x for home delivery).

In both cases, I think having a car is cheaper. Definitely cheaper than going to local stores.

[ju-st]

> Photovoltaics is not environmentally friendly.

citation needed

[atemerev]

https://www.google.ch/amp/spectrum.ieee.org/green-tech/solar...

[Tade0]

It says that the dirtiest solar panels have a carbon footprint of ~70g/kWh.

Even in Germany or the US with their extremely high electricity consumption this amounts to 1 tonne of CO2 per capita annually - that's around the target footprint for sustainability.

For comparison coal has a footprint of ~880g/kWh and natural gas ~450g/kWh.

In short, solar panels are currently environmentally friendly.

[atemerev]

Carbon footprint is not the only metric of environmental damage.

[Tade0]

Every other kind of environmental damage(as long as it's containable) can be prevented or undone with enough energy, so as long as that's being done all we need to worry about is the energy ROI.

Solar panels, throughout their life cycle, produce much more energy than it is required to produce and recycle them in an environmentally friendly way.

[rbanffy]

Sure, but carbon is the gun pointed at our heads right now. I suggest paying attention to it.

[dahauns]

Two paragraphs in:

"The good news is that the industry could readily eliminate many of the damaging side effects that do exist."

[atemerev]

The bad news is that this is quite expensive and unsustainable without massive subsidies.

[rbanffy]

> massive subsidies.

That's what governments are for.