A Framework for Comparing the Viability of Different Desalination Approaches

Key Points Most renewable powered desalination schemes are hybrids that displace fossil fuel power when renewable power is available. Their economic viability depends only on whether the renewable power source can generate electricity more cheaply than the fuels that it displaces. The framework used here by KAPSARC compares standalone plants that are powered only by renewable energy and therefore incorporate storage, either of input energy to allow the plant to run full time or of produced water to level out the production of an oversized plant. The commerciality of such approaches is a function of the relative costs of three elements: energy storage (electricity or heat); the cost of standby desalination capacity (including treated water storage); or the relative costs of renewable and conventional energy. Our research shows that, with the present state of technology, membrane plants are more cost-effective than thermal plants. It is also more cost-effective to oversize the desalination plant and store water on the back end than to store electric power on the front end. The best current configurations are only competitive if the opportunity cost of the avoided fuel consumption is more than $60/barrel of oil equivalent (BOE).

关键要点：绝大多数以可再生能源为动力的海水淡化方案均为混合型，可在可再生能源供应充足时替代化石燃料电力。此类方案的经济可行性取决于可再生能源发电成本是否低于其所替代的燃料成本。KAPSARC在本研究中采用的框架对比了仅由可再生能源供电的独立工厂，此类工厂需配备储能设施，以便全天候运行或平衡超大规模工厂的产出。此类方法的商业可行性取决于三个要素的相对成本：储能（电力或热能）；备用海水淡化产能成本（包括处理后的水存储）；以及可再生能源与传统能源的相对成本。我们的研究显示，在当前技术水平下，膜式工厂的成本效益优于热式工厂。此外，在末端存储淡水相较于前端存储电力而言，扩大海水淡化工厂的规模在经济上更为可行。目前最佳配置仅在避免燃料消耗的机会成本超过每桶60美元的石油当量（BOE）时具有竞争力。