The official list of energysuplliers can be found on the site of Brugel.

https://www.brugel.brussels/acces_rapide/les-acteurs-du-marche-10/liste-des-fournisseurs-28

EDF Luminus

http://edfluminus.edf.com/

Electrabel

http://www.electrabel.be

Eneco Belgium

http://www.eneco.be

Energie 2030

http://www.energie2030.be/

Lampiris

http://www.lampiris.be

OCTA+ Energie SA

http://www.octaplus.be

Essent Belgium

http://www.essent.be

E.ON Belgium

http://www.eon-benelux.be

Nuon Belgium

http://www.nuon.be

EDF Belgium

http://www.edfbelgium.be

Trianel (electricity)

http://www.trianel.com

Distrigas (gas)

http://www.distrigas.be

GDF Suez (gas)

www.gdfsuez.com/

Elexys

http://www.elexys.be/

Scholt Energy Control (electricity)

http://www.scholt.be

Gas Natural Europe (gas)

http://www.gasnatural.com