Decoupled Electrolysis for the Production of Zero-Carbon Hydrogen

为了从电解水中规模化地生产绿色氢气，必须开发出与间歇可再生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关键缺陷，这两个缺陷阻碍了它们在可再生能源驱动的绿色氢气生产中的采用。首先，现有的电解槽不能有效地处理间歇性电力输入。根据定义，可再生能源是间歇性的(有时阳光灿烂，有时不阳光，当阳光照射时，其在地面上的强度不断变化)。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停机-启动模式运行。这会加速电解槽中昂贵组件的降解，还会导致电解氢和氧产品的危险混合物的产生。因此，传统的电解槽需要大量的电源管理设备，以便使用可再生电源输入来安全地工作。如果没有这样的电力管理系统，传统电解槽在直接连接到可再生能源时将产生危险的氢气和氧气混合物，这到目前为止一直是实现由可再生能源驱动的氢气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较高。最先进的电解槽包含昂贵的膜，试图保持氢和氧产品的分离，但这些膜在操作过程中会迅速降解，必须定期更换。这给电解槽的长期运行增加了相当大的成本和复杂性。在这项建议中，我们将建立在“分离电解”的概念上，开发一种可以直接利用太阳能电解水的系统。分离的电解方法有可能解决阻止更多电解用于绿色氢气生产的两个关键问题。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气和氧气混合物的条件下，分离电解允许有效和安全地使用具有可再生能源特性的电力输入。相比之下，去耦合系统产生的气体在混合气体含量方面完全在监管范围之内。我们还能够证明，与传统系统相比，去耦合系统中的膜降解显著减少，这表明去耦合电解槽所需的停机时间和维护成本应该比传统的“耦合”电解槽更低。这两个特点都有望使电解水生产绿色氢气变得更加实用和经济。通过利用去耦合电解的能力，使氢气和氧气的产生在不同的地点、不同的时间和不同的速度发生，我们在这个项目中的目标是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气。

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.