Utilizing　renewable　energy　sources　such　as　wind　and　photovoltaic　to　identify　cost-effective　decarbonization　pathways　for　coastal　receiving-end　power　systems　is　one　of　the　core　challenges　in　achieving　the　goals　of＇carbon　emission　peak　and　carbon　neutrality＇of　China.　By　analyzing　the　techno-economic　differences　between　hydrogen-ammonia　storage　and　existing　energy　storage　technologies　(such　as　electrochemical　and　compressed　air　energy　storage),　a　multi-year　expansion　planning　model　for　power　systems　incorporating　cofiring　coupled　hydrogen-ammonia　energy　storage　under　temporal　decarbonization　constraints　is　established,　and　the　techno-economic　feasibility　of　achieving　low-cost　decarbonization　within　the　power　system　is　explored.　The　actual　data　are　selected　from　Guangdong　power　grid　of　China　for　case　study.　The　results　demonstrate　that,　under　increasingly　stringent　carbon　reduction　constraints,　it　is　necessary　to　progressively　achieve　decarbonization　targets　through　technical　pathways,　such　as　the　newly　added　wind　and　photovoltaic　storage,　the　transition　from　coal　to　gas　in　thermal　power　planning　modes,　and　the　newly　added　hydrogen-ammonia　energy　storage　(including　hydrogen　cofiring　in　gas　turbines,　ammonia　cofiring　in　coal-fired　plants,　and　ammonia　decomposition).　Compared　with　a　decarbonization　mode　relying　solely　on　lithium-ion　battery　peak　shaving,　the　introduction　of　cofiring　coupled　hydrogen-ammonia　energy　storage　technology　can　avoid　overloading　excessive　wind　and　photovoltaic　storage　capacity,　thus　significantly　reducing　the　wind　and　photovoltaic　curtailment　rates.　This　approach　not　only　achieves　intensive　resource　utilization,　but　also　further　reduces　the　decarbonization　cost　of　hydrogen-ammonia　energy　storage　through　the　reuse　of　existing　thermal　power　generation　infrastructure.　Therefore,　the　use　of　hydrogen-ammonia　energy　storage　technology　for　power　system　decarbonization　presents　a　scalable　and　economically　feasible　decarbonization　pathway.　©　2025　Automation　of　Electric　Power　Systems　Press.　All　rights　reserved.