This is a naïve but genuine question.. is shipping trash from the UK to Norway and then setting it on fire better for the environment than burying it? (Or, at the very least, is it better to burn trash than to extract and burn something else?)
"is shipping trash from the UK to Norway and then setting it on fire better for the environment than burying it?"
Definitely! Landfill takes up a lot of space. Yes, it's buried underground, but there is a risk that harmful toxins or chemicals can leak into the soil. Landfill gases can leak into the air. A lot of that rubbish will not decompose.
The UK has a landfill tax to discourage excess waste, but unlike Sweden and Norway, we have not come up with clever, forward-thinking solutions to tackle the problem.
One thing about shipping costs are that they're very low.
A number from oil tankers: the "freight cost" of shipping a supertanker's worth of oil halfway around the world works out to a few pennies per gallon -- 1% of the net cost, and an even smaller fraction of the energy content.
I don't know about the Swedish one but the Norwegian one in the other linked article says:
Oslo, a recycling-friendly place where roughly half the city and most of its schools are heated by burning garbage — household trash, industrial waste, even toxic and dangerous waste from hospitals and drug arrests — has a problem: it has literally run out of garbage to burn.
I live in a Swedish city, and I recently visited the local "garbage burning" power plant. It's not like the trash is just burned and the fumes released into the atmosphere, they pass through like 10-15 different types of filters removing and recycling different particles. The fumes that finally are released supposedly have a very negligible environmental impact. I'd link you some sources, but I got this information first-hand from the plant engineers, not sure where to look.
There exist a NOx tax (since 1992) for polluting the air with nitrogen oxides when burning garbage. But how much a furnace pollutes when doing that, not sure at all.
The amount of polluted nitrogen oxides to the level of produced energy unit has dropped some the last few years, but not much.
The general nitrogen oxide levels in Sweden has been reduced since the 90s according to this source
A number of WTE plants do a couple of things -- 1) biological / wet fraction goes to a digester for methane, which is either burned as additional fuel or sold to municipalities, 2) solid waste is burned, 3) ash from burning used for additional projects (road, train beds, etc).
Most also do cogeneration as well (energy + heat/steam distribution).
