Decoupled Electrolysis for the Production of Zero-Carbon Hydrogen

为了从水的电解中大规模生产绿色氢，必须开发与间歇性可再生能源发电更兼容的新型电解槽。这是因为现有的电解槽存在两个主要缺陷，这阻碍了它们采用可再生能源驱动的绿色氢气生产。首先，现有的电解槽不能有效地处理间歇性的电力输入。根据定义，可再生能源是间歇性的（有时太阳发光，有时不发光，当它发光时，它在地面上的强度是不断变化的）。例如，如果直接连接到太阳能电池板，传统的电解槽将以恒定的启停模式运行。这加速了电解槽中昂贵部件的降解，也导致电解氢和氧产物的危险混合物的产生。因此，传统的电解槽需要重要的电源管理设备，以便使用可再生能源输入安全工作。如果没有这样的电源管理系统，传统的电解槽在直接与可再生能源耦合时将产生危险的氢和氧混合物，这是迄今为止实现由可再生能源驱动的氢生产经济的主要障碍。传统系统的第二个主要缺点是操作和维护成本高。最先进的电解槽包含昂贵的膜，试图将氢和氧产物分离，但这些膜在运行过程中迅速降解，必须定期更换。这为电解槽的长期运行增加了相当大的成本和复杂性。在这个提案中，我们将以“解耦电解”的概念为基础，开发一个可以直接使用太阳能电解水的系统。解耦电解方法有可能解决两个关键问题，阻止更多的电解用于绿色制氢。事实上，在我们的初步结果中，我们已经表明，在传统电解槽产生危险的氢和氧混合物的情况下，解耦电解允许有效和安全地使用可再生能源的电力输入特征。相比之下，解耦系统产生的气体在混合气体含量方面完全在规定的限制范围内。我们还能够证明，与传统系统相比，在解耦系统中膜降解显著减少，这表明解耦电解槽应该比传统的“耦合”电解槽需要更少的停机时间和更低的维护成本。这两个特点都有望使电解水生产绿色氢更加实用和具有成本效益。通过利用解耦电解的能力，使氢气和氧气在不同的地方、不同的时间和不同的速率发生，而这些速率彼此之间并不相连，我们的目标是在这个项目中展示在阳光驱动的压力下生产纯氢。这将为未来扩大这些系统的规模打开大门，以安全高效地生产由可再生能源驱动的零碳氢。

In order to produce green hydrogen at scale from the electrolysis of water, new electrolysers that are more compatible with intermittent renewably-generated power must be developed. This is because existing electrolysers suffer from two key drawbacks which hampers their adoption for green hydrogen production driven by renewable power sources. Firstly, existing electrolysers do not handle intermittent power inputs effectively. Renewable power sources are by definition intermittent (sometimes the sun shines, and sometimes it doesn't, and when it is shining its intensity on the ground is constantly varying). If connected directly to a solar panel for example, a conventional electrolyser would be operating in constant stop-start mode. This accelerates the degradation of expensive components in the electrolyser and also leads to the production of dangerous mixtures of the hydrogen and oxygen products of electrolysis. As such, conventional electrolysers require significant power management apparatus in order to work safely using renewable power inputs. Without such power management systems, conventional electrolysers would produce dangerous mixtures of hydrogen and oxygen when coupled directly to renewable power sources, which hitherto has been a major barrier to the realisation of a hydrogen production economy driven by renewable power. The second major drawback of conventional systems is their high operational and maintenance costs. State-of-the-art electrolysers contain expensive membranes to try and keep the hydrogen and oxygen products separate, but these degrade rapidly during operation and must be replaced regularly. This adds considerable cost and complexity to long-term electrolyser operation.In this proposal, we will build on the concept of "decoupled electrolysis" to develop a system that can use solar power directly for the electrolysis of water. A decoupled electrolysis approach has the potential to solve both of the key issues preventing greater uptake of electrolysis for green hydrogen production. Indeed, in our preliminary results, we have shown that decoupled electrolysis allows the effective and safe use of power inputs characteristic of renewable sources under conditions where a conventional electrolyser produced a hazardous mixture of hydrogen and oxygen. In contrast, the gases produced by the decoupled system were well within regulatory limits in terms of mixed gas content. We were also able to show that membrane degradation was significantly reduced in a decoupled system relative to a conventional system, suggesting that decoupled electrolysers should require less downtime and incur lower maintenance costs than conventional "coupled" electrolysers. Both of these features could be expected to make electrolysis of water to produce green hydrogen significantly more practical and cost-effective. By leveraging the ability of decoupled electrolysis to allow hydrogen and oxygen generation to take place in separate places, at separate times and at rates that are not connected to each other, we aim in this project to demonstrate the production of pure hydrogen at pressure driven by sunlight. This will open the door to future scale-up of these systems for safe and efficient production of zero-carbon hydrogen driven by renewables.