We outline a realistic energy transition roadmap for Italy, in which the whole energy demand is met by electricity generated by low cost renewable energy technologies, namely solar photovoltaic, wind and hydroelectric power. We assess the amount of extra power and storage capacity to be installed along with costs, return on investment and payback time. Based on cost, renewable nature and scalability, storage in energy dense polysaccharides enzymatically synthesized from carbon dioxide, water and surplus electricity is proposed to meet the significant storage requirements.