PDF Publication Title:
Text from PDF Page: 047
Both alkaline and PEM electrolyser systems have been certified to provide primary reserves (i.e. the most rapid, short term grid service) (IRENA, 2019b; thyssenkrupp, 2020), therefore highlighting how flexibility is more of a design issue related to balance of plant components and sizing. Many small modular stacks, for example, each one with its own rectifier, make a significantly more flexible electrolyser plant than a single large stack with single rectifier, regardless of stack technology. In terms of hydrogen storage, hydrogen in a gaseous form can be stored in two favoured approaches: pressurised steel tanks and underground reservoirs. Hydrogen can also be liquefied. This would deliver about 75% higher energy density than gaseous hydrogen stored at 700 bar, while requiring the equivalent of 25%-30% of the energy contained in the hydrogen. Promising developments in large scale facilities show energy consumption as low as 6 kWh/kg of hydrogen (Walnum et al., 2013). Underground storage of hydrogen using, for instance, salt caverns is considered to be the most appropriate solution to store hydrogen on a large scale. This method comprises some interesting storage characteristics, such as low investment costs, high sealing potential, and low cushion gas requirement (Ozarslan, 2012). Salt caverns typically allow storing hydrogen from 100 bar up to 275 bar. Hydrogen storage at output pressure from the electrolyser is useful, if the objective is to maximise flexibility, as mechanical compression can limit the speed at which electrolyser output can change. The use of pressurised electrolysers (e.g. 30 bar, achievable with both alkaline and PEM technologies today), in combination with a buffer to decouple the electrolyser operating regime from the compressor operating regime, helps to prevent the compressor from becoming the bottleneck for the flexibility of the electrolysis facility as a whole. As far as the ability of electrolysers to provide flexibility to the power system, this can be achieved at multiple time scales. A mapping of system services (IRENA, 2020f) is provided in Figure 16. Except for the provision of inertia, electrolyser facilities can provide all system services, if designed with this in mind. While PEM might eventually be more effective than alkaline for fast frequency response (FFR), batteries are clearly more efficient and effective in providing fast response to system operator’s signals and can quickly saturate such a market, which makes any additional cost incurred for designing electrolyser facilities capable of providing FFR questionable in terms of potential return. For the remaining services, all electrolyser technologies can provide them effectively without technical challenges, provided they are designed with grid service provision in mind. The electrolyser stack is fast enough to follow fluctuations from wind and solar. The limitation arises from the surrounding equipment. Seasonal rather than short-term may be hydrogen’s highest value Where hydrogen has a significant role to play in terms of flexibility provision in future decarbonised power systems is in long duration storage and system adequacy. The seasonality of solar, wind and hydropower resources can provide challenges in terms of adequacy – if not every year, at least in unusual weather years (e.g. dry years, or years with extended periods of low wind). Hydrogen from renewable power can be stored cost effectively – for example, in salt caverns – and can be used for power generation in these particular periods (Diesendorf and Elliston, 2018). Notably, if hydrogen-to-power is performed using gas turbines or internal combustion engines, hydrogen can then also contribute to the provision of system inertia (unlike fuel cells). Based on IRENA analysis, in the Transforming Energy Scenario (TES) of the Global Renewables Outlook a significant capacity of electrolysers will be deployed by 2050. IRENA developed a global power system model based on this scenario that includes electrolysers as purchasers that buy electricity when it is most affordable, with the objective of producing hydrogen. In the 2050 TES scenario, renewables will supply 86% of total electricity, with solar and wind alone providing over SCALING UP ELECTROLYSERS TO MEET THE 1.5°C CLIMATE GOAL 47PDF Image | GREEN HYDROGEN SCALING UP ELECTROLYSERS
PDF Search Title:
GREEN HYDROGEN SCALING UP ELECTROLYSERSOriginal File Name Searched:
IRENA_Green_hydrogen_cost_2020.pdfDIY PDF Search: Google It | Yahoo | Bing
Salgenx Redox Flow Battery Technology: Power up your energy storage game with Salgenx Salt Water Battery. With its advanced technology, the flow battery provides reliable, scalable, and sustainable energy storage for utility-scale projects. Upgrade to a Salgenx flow battery today and take control of your energy future.
| CONTACT TEL: 608-238-6001 Email: greg@salgenx.com | RSS | AMP |