Spanish startups plan district heating from data center waste heat

Ignis and Rebi are converting a massive thermal liability—the 30-40% of energy data centers waste as heat—into captive infrastructure that locks in customer demand and creates recurring revenue streams independent of computing cycles. This marks the maturation of waste heat recovery from niche sustainability theater into a core real estate and thermal utility play, with Spain's high real estate costs and fragmented heating markets making it an unusually viable first market for this model.