I'm about 30km outside Reykjavík, in Iceland.
And yes, earlier today, I was swimming in power plant wastewater.
Which is not something I'd usually recommend.
If you were at a coal-fired power plant,
well, even if you were just swimming in the water
that had been boiled to spin the turbines and then cooled back down again,
well, there are enough stories about coal ash contamination,
with arsenic and mercury and selenium, that it would not be safe.
For gas and nuclear plants,
as long as the water's treated on the way out,
you'd probably be fine? I think?
It's one of those things where I wouldn't want to chance it.
But that blue-white water is in the Blue Lagoon.
Now, the management there are very careful about how they phrase it.
They prefer to talk about the skin care and health benefits
that they claim come from the silica in the water, but...
yeah, it's geothermal power plant wastewater.
Okay, a quick diversion here: most cities in the world have a cold water mains supply.
There's a grid of cold water to all the houses and buildings,
and it's heated on-demand when it's needed in each building.
But Iceland is geologically active:
in parts of the country, there are high-pressure reservoirs of hot water
not too far underground, where underground rivers meet hot rocks.
In some places, those reservoirs break through and reach the surface naturally.
So near those places, it's economical to drill a borehole down into the ground
and capture the superheated, high-pressure steam and water that come back up.
There are two things you can do with that hot water and steam.
It's not drinkable, first of all,
it's filled with silica and other bits of dissolved rock,
but you can put it in a heat exchanger,
and use it to heat up fresh, clean cold water,
and then you can send the resulting clean hot water
down a pipeline to paying customers.
And this is one of those pipelines!
There is hot water speeding through this to Reykjavík.
It doesn't actually feel warm, if it did the pipe wouldn't be doing its job,
because the water only loses a couple of degrees over dozens of kilometres,
but yes, hot water speeding through that.
Icelandic cities have separate hot water and cold water grids.
If your home is connected to that grid you don't need a water heater.
So, okay, that's hot water. If you want electricity instead,
you can spin a turbine using the high-pressure steam that's coming up,
and generate clean power that way. Technically, you can do both,
but pipelines are expensive and there's a lot of hot water around here,
so often it's just electricity or hot water.
Even a massive, industrial-size geothermal borehole will last a few decades
before it starts to run out of heat, and when that happens,
you can just open another one a few kilometres away.
The old one will get back up to temperature sooner or later,
the Earth is not going to run out of heat.
Which means Iceland has a massive supply of hot water.
High up on a hill above Reykjavík, there's this beautiful building called Perlan.
It's got exhibitions about the natural wonders of Iceland
and a revolving restaurant and an observation deck.
But the big round things on the outside aren't part of the exhibitions:
they're the enormous hot water storage tanks that the building was built around.
Perlan is a water tower, just like any other you'd find around the world,
except it stores hot water.
There's so much of it that, while it's not free, it's very very cheap.
If your house is a bit too warm in winter in Iceland, you don't turn the heating down:
you just open a window and let some fresh air in.
Iceland also has quite a lot of fresh air.
When it's snowing, the pavements are heated up by hot water pipes underneath.
Last time I was here was in winter,
the lake behind City Hall was frozen over, the ice was strong enough to safely walk on.
In one corner, there's a pipe constantly pouring a bit hot water into that lake,
just so the ducks have somewhere to swim.
And yes, there are natural hot springs elsewhere in Iceland,
there are natural hot spring beaches elsewhere in the world,
but Reykjavík has an artificial hot water beach:
they just pump hot water into that lagoon to heat it up a bit.
There's a hot tub down there!
But this isn't power plant wastewater.
It's regular water, like you'd get out of the cold tap in your home,
just heated up in a heat exchanger by the high-pressure undrinkable water and steam
that comes up from the boreholes at the geothermal power plants.
The two never touch.
So there's one loose end here:
after that high-pressure steam comes up to the surface and gets used…
where does it go?
Well, once it's cooled down a bit, the geothermal plants
just dump the water out onto nearby rocks.
Those rocks are permeable, the water slowly sinks through them,
and over decades it will make its way back to where it came from.
Mostly.
When you're dumping that much water out, though,
it will tend to form pools and… lagoons.
Particularly when it's got a lot of silica in it.
And the story from there is simple:
someone went bathing in one of those pools, thought it helped their skin condition,
and a few decades of construction and marketing later
the Blue Lagoon is one of the "wonders of the world"
and they charge more than €30 for a basic ticket.
And I don't want to knock that too much!
Because yes, there is some research that says bathing in geothermal water like that
helps some skin conditions, and there is a big difference
between wild swimming in a mysterious hot-water pool
and bathing in a well-regulated geothermal spa
that gives you a towel and offers in-water massages.
But if you feel like being cynical, then yes,
that is power plant wastewater.
Whew.
Iceland is beautiful.
Bit wet. But beautiful.