Thanks for these hints, Andrew.

Inspired by your location data quality checking, I have just sent all ~12000 EPER addresses in parallel to Google, Yahoo and MapQuest Geocoding APIs, via a simple shell script. I am now trying to get the best out of the geocoded locations. Gecoding seems to work fine in many West-European countries. As expected: the results a somewhat more fuzzy in Eastern Europe.

There are also some nitty gritty details like the geocoded location and original EPER location are both correct, although there is a distance of 100 km between them: the address in EPER refers to some company headquarter, whereas the EPER coordinate refers to a remote factory, waste dump, or whatever site (which is the actual source of the emissions, rather than their office building).