In March 2005, firmus energy was formally awarded supply and distribution licenses for the development of a natural gas network outside greater Belfast.

To date firmus energy has developed its network to Ahoghill, Antrim, Armagh, Ballyclare, Ballymena, Ballymoney, Banbridge, Bessbrook, Broughshane, Bushmills, Coleraine, Craigavon, Cullybackey, Derry~Londonderry, Laurelvale, Limavady, Lurgan, Maghaberry, Magheralin, Moira, Newbuildings, Newry, Portadown, Portstewart, Tandragee, Warrenpoint.

It also supplies natural gas in Greater Belfast to approx 60,000 business and domestic customers. Having been awarded a licence to supply electricity in 2009, firmus energy was the first supplier to offer 'dual fuel' energy contracts in Northern Ireland and currently supplies power to large industrial customers.

Today, 111,000+ homes and businesses across Northern Ireland are already enjoying the comfort and convenience of natural gas and lower fuel bills from firmus energy.