英国光伏电站
Hydrogen’s role in easing solar curtailmentOctober 24, 2022
Curtailment is a rising threat to solar PV, exacerbated by antiquated grids and a power system in transition. But green hydrogen electrolysis is emerging as a potential solution to the problem, taking excess solar and converting it into hydrogen for either long-duration storage or use by other industries, writes Alissa Tripp, senior research and commercial analyst at Octopus Hydrogen.
削减发电（弃光）对光伏发电是一个日益增加的威胁，并被不可预见的电网和电力系统转型放大。但是绿色氢逐渐成为一个潜在的问题解决方案，使用多余的光伏发电并转换为氢能，作为长期保存或者被其它行业使用，章鱼氢能公司高级研究和商业分析师Alissa Tripp写到。
As the UK charts a course towards net zero, renewable power from wind and solar farms will increasingly weigh on an antiquated grid until the system is transformed into one that can handle significant volumes of intermittent generation.
随着英国谋划净零方针，风能和太阳能等可再生能源发电将逐渐增加，直到系统转变到能接纳大量的间歇发电机组。
To date, curtailment has been a key tool for managing grid constraints and locational issues around generation. However, developers such as Octopus Hydrogen are driving forward the nascent green hydrogen market and presenting a potential solution to these problems. Here we explore how electrolysers co-located with solar installations can be mutually beneficial as we transition towards a zero-carbon grid.
至今，削减发电作为一个关键的工具来管理电网网络限制和当地发电问题。然而，章鱼氢能公司等开发商零正朝着氢能市场，并且提供一个潜在的解决新能源限制的方案。当我们朝着一个零碳电网转变时，我们探索制氢如何与光伏安装共存并可以相互受益。
The role for green hydrogen
氢能的角色
Electrolysis is the process of using electricity to split water into hydrogen and oxygen. If low-carbon or renewable electricity is used then the hydrogen produced is considered green. With current technology it takes roughly 60kWh to produce 1kg of green hydrogen, but when it’s used in a fuel cell it achieves roughly 30kWh out. This round-trip efficiency means green hydrogen isn’t suitable for all applications; it makes much more commercial sense to electrify sectors such as cars and domestic heating, for example.
电解是利用电将水分解成氢气和氧气的过程。如果是低碳或者可再生能源发的电被用来制氢，则认为是绿色的。现有的技术下大约需要60度电能制成1千克绿色氢能，但是当它作为燃料时可以达到30度电的输出；例如在汽车和家庭取暖更具商业意义。
However, green hydrogen plays a key role in many countries’ decarbonisation plans. Its benefits can be particularly felt in hard-to-abate sectors such as heavy goods vehicles (HGV) and out-of-town bus routes, where the weight of lithium-ion batteries rules out electrification. Aviation and shipping are other sectors where green hydrogen fuel replacement is being explored, and in heavy industry such as steel production green hydrogen is a promising replacement for coking coal.
然而，绿色氢能在很多国家的去碳化发展计划中起到一个关键作用。这样使得高减排难度的部门，比如重型货车和郊区公交线路获益非常，这些部门因锂电池的重量而弃电。航空和航运，绿色氢能正在被开发应用，并且在钢铁生产等重工业里面绿色氢能是一个有希望的煤炭替代品。
How does an electrolyser benefit a solar farm?
电解制氢如何有益于光伏电站？
When embarking on a green hydrogen project, developers must decide on the renewable power source. Co-location with wind produces more green hydrogen than with solar due to higher load factors, but in the UK that likely means production in Scotland. This introduces higher logistics costs to move the gas south, and potentially also higher development costs due to the terrain and isolation of some Scottish wind farms.
当开始一个绿色氢能项目时，开发商需要确定可再生电力的来源。与风电更过的共存，是因为风电比光伏发电有更高的荷载因子，但是在英国这样可能意味着在苏格兰生产（英国将近45%的风能位于苏格兰）。这需要较高的物流成本来向南部运送氢气，并且因为一些苏格兰风电场的地形和位置偏远的开发成本。
Solar already tends to be located in the south of the UK close to where demand is likely to emerge, resulting in more attractive logistics costs. Both wind and solar co-location require generation forecasting, but it’s easier to have an idea of the shape of solar generation in an upcoming week than it is for wind. This lends itself to scheduling of gas production. However, for a project to go live it must be beneficial to both the electrolyser and solar developer – which begs the question: what value can an electrolyser add to a solar farm?
光伏电站也倾向于坐落在英国南部，靠近需求可能增加的地方，更多的有吸引力的物流成本。风能和光伏并存需要发电预测，但是在未来的一个星期有一个大致的光伏发电量预计要比风电更容易。然而，对于一个项目要生存必须同时有利于制氢和光伏发电，引出一个问题：制氢之于光伏的价值何在？
Overcoming network constraints
克服网络限制
Solar farms are often forgoing revenue due to active network management (ANM), where they agree to the local distribution network operator (DNO) controlling how much power they can output at certain times. This is known as curtailment, and is the option many solar developers opt for in the development phase because the alternative is reinforcing the local grid, which can be expensive and have a long lead time.
光伏发电经常弃光，是因为电网电量饱和，不需要更多电量，电网调度指令不接纳光伏发电和风力发电（基于电网安全等因素发电商需要接受电网调度指令进行发电），弃光多发生于电量需求量低的经济不发达的偏远地区。
The result of ANM is that during these times of curtailment solar farms will not be exporting as much energy as they are capable of, and because payment is on exported volume the solar farm’s revenue stream is reduced.
主动电网管理的结果是光伏发电将不能在可以发电的时间进行发电，进而向电网销售的电量减少收益下降。
Looking forwards, with an increasing number of intermittent generation connections, and particularly on local grids where a ‘last in, first out’ approach is used by DNOs to assign ANM connections, curtailment will increasingly eat into the potential revenue of solar farms. As solar farms are added to the grid and without systemic grid transformation, curtailment for these new developments could be anything from a few percent of expected annual export to tens of percent. ”
未来，将有一个逐渐增加的间歇性发电能源，特别是当地电网调度“后进先出”的电网管理原则，弃光现象将逐渐蚕食光伏电站的潜在收益。光伏发电接入电网，电网并没有系统转变，弃光对于开发商可能损失预计升高至10%的年度发电量。
“Electrolysers of 5 – 20MW scale provide an ideal complement to solar farms of up to 100MW, providing a much-welcome revenue stream for some of the power that would otherwise have been curtailed”
5至20兆瓦规模的电解制氢可以为100兆瓦光伏发电场提供一个理想的补充，提供了一个更受欢迎的营业收入，否则多余发电可能会被削减或者浪费掉。
This is where electrolysers can come in: electrolysers can be directly connected via a private wire to the solar farm, with a modest import grid connection to satisfy power demand at times when the solar isn’t generating. With well-planned commercial structuring the electrolyser can have no impact on the price the solar developer sells its exported power for; indeed, it could even provide more competitive pricing.
这是电解制氢可以进来，电解制氢可直接利用光伏电站发出来的电，当光伏电站不发电时利用电网的电也比较少。通过较好的商业结构，制氢可以不影响光伏开发商向电网售电，实际上，制氢甚至可以提供更加具有竞争的价格。
The behind-the-meter connection allows the electrolyser to use power that can’t be exported due to the ANM connection, i.e. curtailed power. This provides the solar farm with access to a pricing mechanism for its curtailed power, restoring some of the revenue stream lost to ANM. As curtailment is generally still a modest subset of total production this alone isn’t enough to make a solar project viable in the development phase. But it’s a helpful and non-negligible revenue stream that only increases in value as curtailment on the distribution grids increases. Solar farms are currently being commissioned without revenue for curtailed power, so this is pure upside for the solar developer.
售电电表后端连接（发电侧）可以利用电网不能消纳的电量制氢，比如被削减的弃光发电量。这样可以为光伏发电站提供一个消减电量的价格机制途径，恢复一部分由于电网管理而损失的收益。电量消减或者弃光仅仅是全部发电量的一个小部分，光伏电站单独制氢不足够令光伏项目在开发阶段具有可行性。但是仅在电网电量削减增加的时候是有用的和不可忽视的收益。光伏电站目前是未考虑电量消减的，光伏制氢是对光伏开发商的一个正推动。
Achieving the best balance
达到最佳平衡
The optimal configuration of solar and electrolyser is not to have them at the same capacity, but to scale back the electrolyser to best balance power from the solar and power from the grid. Take a 70MW solar farm as an example: if this was connected to a 70MW electrolyser then only during solar peak in summer would there be enough solar generation to come close to making use of the electrolyser capacity. The rest of the time the electrolyser would either be idle or drawing power from the grid, incurring expensive grid charges.
光伏和电解制氢最优的组合是各自容量不同，而是在平衡光伏发电和电网供电之间的最佳平衡。一个70MW光伏电站在夏季高峰期可以发出足够多的电量来电解制氢。剩余时间将从电网获取电量，昂贵的电网电价。
A more suitable alternative would be to connect a 10MW electrolyser to the 70MW solar farm via private wire, with a grid import connection of perhaps 2 – 4MW. The electrolyser would then draw the first 10MW of generation from the solar and the rest of its power from the grid. This results in the electrolyser using approximately 40% of the solar farm’s annual generation, with the remaining 60% exported to grid. Octopus Hydrogen has assessed alternative structures, such as a simple off-grid solar and electrolysis setup but concludes that this is the optimal configuration.
一个更加合适的方案是一个70兆瓦的光伏发电带动10兆瓦的电解制氢，并且2至4兆瓦的制氢从电网取电。第一个10兆瓦制氢用电首先使用光伏发电，其余的从电网取电。这样电解制氢用消耗大约40%的光伏年发电量，剩余60%的光伏发电向电网输出。章鱼制氢公司已经评估了另外的结构，比如作为一个离网的光伏发电站制氢，但是认为这是最佳组合。
It allows the solar developer to achieve maximal prices for power whilst preserving flexibility in how the electrolyser can be run.
光伏电解制氢使得光伏开发商获得发电最高价格的同时保持灵活性。
When it comes to utilisation of the electrolyser, it turns out that the best value is not achieved by running it at 100% and maximising the gas production. This is because the price of power is roughly two-thirds of the cost stack when it comes to producing green hydrogen. Power prices vary greatly by half hour just before delivery and it turns out that 40 – 50% average utilisation is the best way to run an electrolyser, turning it up in times of high wind and solar generation, and switching it off during expensive peak periods. Through winter the electrolyser will be drawing relatively more power from the grid than the solar farm, so it’s important to have an import connection that will suffice for the required level of hydrogen production.
光伏制氢的最佳价值不是100%运行和最大化氢气产量。这是因为售电的价格大约是光伏制氢的三分之二的成本。在输送之前半小时电价波动巨大，40%至50%的利用是运行电解制氢的最佳方式，在风电和光伏发电高峰期调大制氢，在电价高峰期停机。在冬季电解用电将从电网取电比光伏发电要多，所以有个电网接入连接来确保制氢生产所需的足够的电力是重要的。
光伏发电与电解制氢功率曲线图
An example electrolyser schedule for 10MW of electrolysis connected to 70MW of solar. The schedule is for an example April day and takes into account both expected renewable generation from the solar farm and forecast power prices for the day. Image: Octopus Hydrogen.
示例：70兆瓦光伏项目配套10兆瓦的计划。上表是四月的一天并且考虑了光伏预计发电和预计的电价。
Equipment and expertise
设备和专业知识
To paint a picture of the physical set up, a 10MW electrolyser and its associated kit would require about an acre of land, with enough space for an HGV turning circle. The main pieces of equipment required are an electrolyser with a water supply, a compressor to compress the gas to the required pressure for the offtaker, and either mobile or static storage. If offtakers are coming to the site to refuel directly then a refuelling unit will also be required, though this can be combined with the storage. Supply chain lead times can be up to 12 months, and the configuration of all this kit and the tailoring of it to specific solar projects requires a high level of engineering expertise.
10兆瓦电解制氢需要一英亩土地，和重型货车转弯场地。主要设备是有供水的电解槽、气体压缩机、移动或者静止的存储设施。如果运输车来到场地加氢还需要一个加氢装置。这也可以和储存结合起来。建设周期长达12个月，并且所有的设备和与光伏项目的匹配都需要一个高水平的工程专业知识。
The obstacles to achieving planning permission are not dissimilar to those faced by battery projects. However, unlike batteries, which overwhelmingly attain their revenue streams via ancillary services, a deeper knowledge of energy markets is required to make an electrolysis project viable. This is because the bulk of the returns made on an electrolyser depend on how effectively demand is shifted throughout the day, rather than in frequency response. Octopus Hydrogen has utilised its UK power expertise to build software that allows remote controlling and optimal scheduling of hydrogen production. This allows a hydrogen producer to minimise the cost of power and maximise the greenness of gas produced.
获得规划许可的障碍与电池储能项目面临是一致的。然而，不同于电池全部通过辅助服务获得收益，电解制氢需要有一个能源市场更深的知识使得项目可行。这是因为电解制氢的主要收益依靠需求如何有效地在一天中轮换，而不是频率响应。章鱼氢能公司已经利用他们在用过的电力知识来建设可以远程控制和优化氢能生产的软件。这样使得氢能生产者最小化电力成本和最大化氢能生产的绿色。
Limits to retrofitting
改进限制
In terms of physical feasibility, it is perfectly possible for electrolysers to be retrofitted to existing solar developments, but in practice this is unlikely to happen due to the requirements of green hydrogen subsidies. One such subsidy comes from the Renewable Transport Fuel Obligation (RTFO), whereby certificates are awarded for green hydrogen sold into transport. Similar to the UK’s Renewable Obligation Certificates, these can be sold into the market of participants who must comply with the RTFO.
在可行性方面，电解制氢改进现有光伏开发限制是完美可行的，但是实际上由于绿色氢能的补贴要求这是不可能发生的。补贴来自于可再生运输燃料义务(Renewable Transport Fuel Obligation)，为向运输出售的绿色氢气授予补贴证书。类似于英国的可再生义务认证，证书可以卖给市场参与者，参与者必须服从RTFO。
This subsidy has an ‘additionality’ requirement on the power used in the electrolysis, dictating that it must be from new-build renewable connections. Curtailed power from existing farms does also qualify, but the level of curtailment most existing sites are subject to provides an insufficient load factor to make the commercials of an electrolyser project there stack up. Other subsidy schemes such as the Hydrogen Business Model also include additionality criteria as part of their assessment of applications, but it’s not a requirement.
这个补贴对电解用电有一个额外性要求，表明电解用电必须来自新建的可再生接入。现有项目的消减电量也符合，但是现有电站电量消减水平受制于提供一个不足的负荷因子来商业化制氢。另外的补贴，比如氢能商业模型同时包含额外性，不是必须的。
Solar to play a key role in green hydrogen production
光伏在氢能制造中起到关键角色
The UK’s plans for decarbonisation rely on building more and more wind and solar, which consequently comes with ever higher levels of curtailment. Electrolysers of 5 – 20MW scale provide an ideal complement to solar farms of up to 100MW, providing a much-welcome revenue stream for some of the power that would otherwise have been curtailed.
英国的去碳化计划依靠建设更多的风力和光伏发电，后果是更高的电力削减比例。5至20兆瓦规模的电解制氢可以为一个100兆瓦光伏发电站提供一个理想的补充，提供一个更加受欢迎的收入来源，否则一些电量将会被削减。
At the outset of the green hydrogen industry the combination of renewable generation location and offtaker demand will dictate where the projects are within the UK. As the market matures and logistics can be handled at scale it is likely that more production will come online abroad. In addition to locations being skewed towards demand hubs, places with an abundance of space and cheaper, more reliable renewable energy are strong contenders to become green hydrogen production hotspots, where electrolysers can be installed in the hundreds of megawatts.
在绿色氢产业的开端和可再生能源电站地点和氢能需求的结合将决定项目是在英国的什么地方。随着市场成熟和物流可以大规模处理，很可能更多的产量来自海外。除了位置在向靠近需求的地方布置，拥有大量空间、更加便宜和更加可靠的可再生能源都将成为绿色制氢的热门地点，电解制氢规模可达几百兆瓦。
Solar will play a key role in fuelling the production of green hydrogen. Though the benefit electrolysis can offer solar farms today mainly revolves around providing revenue for curtailed power, in the future green hydrogen will play a much more central role in the commercials of newbuild solar.
光伏将在绿色制氢中起到一个关键角色。尽管目前电解制氢可以为光伏发电站提供主要是围绕削减发电带来的收益，将来绿色制氢将在重建光伏场的经济中发挥一个更加核心的作用。
①原文链接：https://www.pv-tech.org/hydrogens-role-in-easing-solar-curtailment/
②氢动力汽车前景分析（二）：氢能源和氢基建 https://zhuanlan.zhihu.com/p/350422485
③Electrolysers https://www.iea.org/reports/electrolysers
④光伏制氢靠谱吗？ https://zhuanlan.zhihu.com/p/403273354
⑤光伏制氢-北极星太阳能光伏网 (bjx.com.cn) https://guangfu.bjx.com.cn/topics/guangfuzhiqing/
⑥宁夏回族自治区氢能产业发展规划 https://app.myzaker.com/news/article.php?pk=636f35a78e9f09621046efc8
⑦一文看懂什么是光伏制氢! https://www.kesolar.com/headline/165499.html
⑧英国可再生能源补贴政策：可再生能源义务、上网电价补贴、差价合同 https://news.bjx.com.cn/html/20171213/867255-1.shtml
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