HH-Gen: High performance green hydrogen generation from solar energy

2018年，IPCC得出结论，将全球变暖控制在2ºC以内需要到2030年将二氧化碳排放量在2010年的基础上减少25%，到2070年实现净零排放。氢是一种清洁能源解决方案，代表了防止灾难性气候变化所需的向可再生能源过渡的重要方面。由可再生能源生产的“绿色”氢可以解决关键的能源挑战。它为航空、长途运输、化工制造和钢铁等许多行业的脱碳提供了一条途径，在这些行业，减排具有挑战性。氢气在供应和使用方面都是一种多功能燃料，它可以长时间储存大量能量，并且可以长距离传输能量。它可以使可再生能源提供更大的贡献，并有可能缓解太阳能光伏（PV）和风能等可再生能源的可变输出问题。然而，从可再生能源生产氢气目前是昂贵的，全球90%的氢气生产来自化石燃料（所谓的“灰色”氢）。主要是天然气的蒸汽重整)。尽管从可再生电力中生产氢气的成本正在下降，但要使绿色氢气在成本上与其他替代品具有竞争力，还需要取得重大进展。FocalSun的技术旨在解决生产绿色氢的成本问题。为了实现这一目标，我们致力于消除太阳能制氢过程中的低效率问题。考虑一个连接到电网的大型太阳能电池板阵列，然后连接到电解槽上，通过电解水来产生氢气。有几个效率低下的地方：*光伏板的效率约为18-20%，通常是静态的，不跟踪太阳（这意味着效率实际上低于18-20%）。FocalSun采用双轴聚光太阳能光学系统与高效多结太阳能电池相结合，效率约为45%。结合热能回收，这可以导致超过80%的入射太阳能被捕获，作为制氢系统的一部分使用。*太阳能电池产生直流电，直流电被转换成交流电，通常传输几英里，然后再转换回直流电为电解槽供电。DC/AC和AC/DC转换消耗约5-10%的生产能量。FocalSun的设计使电解槽与太阳能发电系统位于同一位置，从而实现电能的直接耦合，从而消除了这些损失。该项目将解决这些效率问题，使绿色氢与灰色氢相比具有成本竞争力。此外，由于直接耦合配置需要一个紧凑的电解槽，这使我们能够开发高压电解槽，其中用于电解的水被压缩，因此氢在高压下直接产生，从而消除了压缩氢传输的泵送损失。给水加压所需的能量要比给氢气加压所需的能量少得多，因为水的体积变化要小得多。这代表了未来的研发方向，也是进一步降低绿色氢成本的途径。

In 2018, the IPCC concluded that limiting global warming to 2ºC requires a reduction in CO2 emissions of 25% by 2030 compared with 2010 levels, and to reach net zero by 2070\. Hydrogen is a clean-energy solution representing an important aspect of the transition to renewable energies required to prevent catastrophic climate change. "Green" hydrogen produced from renewable sources can address critical energy challenges. It offers a route to decarbonise many sectors such as aviation, long-haul transport, chemicals manufacture, and iron and steel, where it is challenging to reduce emissions. Hydrogen is a versatile fuel, both in terms of supply and use, which can store large quantities of energy for prolonged periods of time, and can transport energy over long distances. It can enable renewable energy resources to provide greater contribution, with potential to mitigate issues with variable output from renewables, such as solar photovoltaics (PV) and wind. However, producing hydrogen from renewable energy resources is currently expensive, and \>90% of global hydrogen production comes from fossil fuels (so-called "grey" hydrogen. mostly steam reforming of natural gas). Although the costs of producing hydrogen from renewable electricity are falling, significant advances are required in the state of the art so that green hydrogen becomes cost competitive with alternatives. FocalSun's technology aims to solve issues with the cost of production of green hydrogen. We seek to achieve this by focusing on eliminating inefficiencies in the processes used to produce hydrogen from solar energy. Consider a large array of solar panels connected to the grid, which is then connected to an electrolyser to generate hydrogen through electrolysis of water. There are several inefficiencies:* PV panels are around 18-20% efficient and typically static and do not track the sun (meaning efficiency is in reality less than 18-20%). FocalSun uses bi-axial concentrating solar optics in combination with high-efficiency multi-junction solar cells, which are ~45% efficient. In combination with thermal energy recovery, this can result in more than 80% of the incident solar energy being captured for use as part of a hydrogen production system.* Solar cells produce DC electricity, which is converted to AC, typically transmitted several miles, then converted back to DC to power the electrolyser. DC/AC and AC/DC conversion consumes around 5-10% of the produced energy. FocalSun is designed so that the electrolyser is co-located with the solar power system, enabling direct coupling of the electrical energy, eliminating these losses.This project will address these efficiencies to enable green hydrogen to become cost-competitive with grey hydrogen. Moreover, because the directly-coupled configuration requires a compact electrolyser, this enables us to develop high-pressure electrolysers, where the water used for electrolysis is compressed so that the hydrogen is directly produced at high pressure, thus eliminating the pumping losses to compress hydrogen for transmission. Pressurising water requires much less energy than pressuring hydrogen gas because the change in volume that occurs is far smaller. This represents a future R&D direction, and a pathway to further reducing the cost of green hydrogen.