Could Ireland survive without importing anything?

Ireland produces enough food especially dairy and meat to feed over 20 million people.

The amount of fish from our waters shipped to Spain and France we’d be ok for seafood

Nope. Because those industries are utterly dependent on imported grain, which the OP has said you can't do.

Edit: Reflecting on this, we have to appreciate that most Irish cattle are kept indoors for 3-4 months per year. Trying to feed the grass in fields during the cold weather would mean weight loss, illness and the fields being in utter mush from the weight of the cattle on wet ground. Without the imported grain and the ability to harvest silage with machinery, the risk is that many cattle and other animals would starve if the disruption lasted for a winter. A cull of a large number of the animals would reduce demand for feed and allow those cattle to be fed to other cattle, oh sorry we don't do that any more, to humans.

Sail boat, donkey and kart, like it was in the old days.

That is what would have to happen if we could not import fuel.

Sailboats

Rods

We'd all have to go shopping in Newry.

Vegans would die out.

Not necessarily a bad thing.

Not a chance. Ireland makes a lot of foodstuffs, but very little actual food.

Sure around here there's thousands of acres given to barley for whiskey .

No way would farmers be able to pivot and provide enough food for the population. Even if we could grow it, we don't have the resources to refine it and transport it.

Just for fun, read the book World War Z about a zombie apocalypse. Nothing to do with the movie. There's a chapter where society is trying to rebuild itself, but no one has even basic skills. There's a lovely bit where a cleaner becomes the supervisor of her former employer, because the employer used to be a digital marketer which is now a useless job

By horse and cart or by bicycle if you hav’nt. horse

Unless we have some way to stabilise the grid with asynchronous generation, very little of our electricity will be coming from Wind or Solar.

We have (at best) 10% of our gas needs coming from Corrib, the rest is imported. In an emergency, GNI will prioritise residential rather than industrial customers. Therefore 0% gas will go towards electricity production. Eirgrid currently has a system stability limit known as the SNSP which is set to 75% for non synchronous sources. That means that for every 1 MW of electricity produced, 25% of it will have to come from synchronous sources such as thermal or hydroelectric.

We have approximately 500 MW of run of river hydro and pumped storage, so in theory we could have 1.5 GW of wind or solar to complement it. But both hydro and pumped storage are energy limited and cannot run at peak output indefinitely. In summertime, unless it's particularly rainy, the hydros won't be able to run much at all. Pumped storage can only run while the reservoir is full, once it is empty, then you have to use your limited electricity to fill it again. In this case, you'd be using the 200 MW of hydro plus 600 MW of wind or solar. But again, if it's not raining, good luck...

Even with the amount of agricultural land we have and our low population density, we'd be just as fcuked as other countries. Societal breakdown would start within hours as thousands of idiots descended on supermakets to fight each other over white bread and toilet roll.

Yep, that's the seasons though.

Our winter is their summer, the alternative is no summer fruits in the off season, or we build vertical farms and grown everything in artificial conditions.

I saw a company selling 40 foot containers which contain everything needs to grow fodder for cattle. They're designed to be dropped in African countries. You feed water, seeds and liquid fertilizer in one side and get a constant feed of grass put the other. I was thinking would it work for human edible grasses too

A lot of NORAs oil is stored in the UK who will absolutely just seize it off us when we need it.

There's only so much seaweed for fertiliser; and there used to be actual killings over access to beaches and ownership of the seaweed thereon back in the old days (Victorian era mostly).

Plenty of the agri co-ops around the country started not as dairies, but as group buying schemes for artificial fertiliser due to the supply problems for natural fertilisers.

There's a reason why the potato was the staple crop in pre-famine Ireland — it's incredibly nutritious. Provided you eat the whole spud, skin and all, then with relatively modest quantities of bacon, salt and some leafy green such as cabbage you're got a pretty good diet. Plus, it stores well without refrigeration, so as long as you grow enough of them you can eat potatoes year-round.

Pre-famine, the Irish peasantry were noted for being surprisingly healthy and well-nourished, given their dire poverty. So, yeah, in the scenario painted by the OP we would likely default to a potato-dominated diet. Boiled potatoes, since that's the most fuel-efficient way of preparing them, and fuel would be at a premium. Pig-meat would be the dominant meat, since you can feed pigs on practically anything and they don't take up a lot of grazing land that could otherwise be used to grow potatoes. Plus, it cures well, which helps with storage. We'd be rearing sheep for wool (we won't be wearing cotton any more, obviously, and in this climate we can hardly go in the nip) and that would mean some lamb meat as well, but that would be mostly seasonal — lamb with the new potatoes. Various greens when in season. A smattering of other root vegetables for variety, and a modest amount of grain production for bread. Salt can be reclaimed from the sea but, alas, no pepper.

One factor not already mentioned is that, if we can't import anything, we have no use for foreign currency — ultimately, all you can do with foreign currency is buy stuff in foreign-land. And if we've no use for foreign currency then our export industries fold, because what's the point? This will free up a large workforce to weed the spud drills, which is good because it's all going to have to be done by hand.

Actually it seems to have changed - they have none in GB anymore; some in NI and other storage locations in Denmark, Spain, Sweden and the Netherlands

Used to be extensively in Wales; I'm guessing Brexit has been an issue.

But the stuff in NI is even shaky - during the extremely hard frosts in ~2010, the UK stopped us getting road salt from the NI salt mines despite pre-existing contracts to do so.

And stuff in Scandinavia or Spain may as well not exist if we aren't allowed access it.

Not too difficult to fix. The reason it stops working is a safety measure to ensure ESB technicians are not at risk from electricity going back to the grid when they're working on the lines. If you install a switch to take you off the grid or isolate a circuit, solar can work in a domestic setting when the grid goes down. Most people don't bother as it's not a major issue and when the power goes, it's generally for a couple of hours.

Does Ireland produce these switches in this hypothetical?

I was only giving a reason as to why most systems go offline when the grid is down, as some people might think it isn't fixable or it's a serious flaw. Obviously, you have an understanding of how solar works, but many people don't.

I already stated in a previous post that components would be a huge issue. Could we produce a switch? I think we could, or we could devise a rudimentary manual switching process. I have seen YouTube videos with very rudimentary switches that work - they're not as safe as would be required with current standards, but beggars can't be choosers. However, with components being an issue, once the inverters start to fail, having the ability to switch would be a moot point.

Cuba is about 36% larger than Ireland (109,880 km² v 70,280 km²) and its population is around double that of Ireland - in 1990 during the fall of the USSR, the population was 10.63 million versus 3.514 million in Ireland at that time.

I agree that it would be very difficult and you are spot on about a couple of bad harvests - with global warming, this is a very real possibility as proven by the last few summers.

I'm just hypothesising about a scenario, and I gave a very broad opinion that didn't take into account a lot of variables. I mentioned Cuba and NK as they have managed albeit with a lot of difficulty. One thing I have learned is that people usually adapt and figure out how to survive.