Saudi Aramco eyes 2019 commercial operation at its giant syngas-fired Jazan power plant and linked refinery. But a lack of related infrastructure and threats from Houthi rebels over the nearby border with Yemen could yet throw the plans off track.

Saudi Aramco this week announced an agreement to form a joint venture with US industrial gases firm Air Products and Saudi private-sector firm Acwa Power to operate an integrated gasification combined cycle (IGCC) power plant at Jazan in the...