تجزیه و تحلیل اقتصادی تولید هیدروژن از برق بادی ایجاد شده برای استفاده در برنامه های کاربردی حمل و نقل
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|28889||2011||9 صفحه PDF||سفارش دهید||7003 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Energy Policy, Volume 39, Issue 5, May 2011, Pages 2957–2965
Wind-generated electricity is often considered a particularly promising option for producing hydrogen from renewable energy sources. However, the economic performances of such systems generally remain unclear because of unspecified or favorable assumptions and operating conditions. The aim of this paper is to clarify these conditions by examining how the hydrogen produced is used. The analysis that has been conducted in the framework of the HyFrance 3 project concerns hydrogen for transport applications. Different technical systems are considered such as motorway hydrogen filling stations, Hythane®-fueled buses or second-generation biofuels production, which present contrasted hydrogen use characteristics. This analysis reveals considerable variations in hydrogen production costs depending on the demand profiles concerned, with the most favorable configurations being those in which storage systems are kept to a minimum.
While the prospects for developing hydrogen use in stationary applications should not be ignored, the main focus today is on the use of this energy carrier in mobile applications. Most studies that have looked into the development of hydrogen consider its use in transport applications and in the framework of ambitious climate policies (European Commission (EC), 2006; Protech-H2, 2009). In this type of context, producing hydrogen from zero-carbon sources would become a prerequisite, albeit not always sufficient on its own, implying important changes in the energy mix used to produce hydrogen beyond 2030: introduction of CO2 capture, the use of nuclear power and the gradual inclusion of higher proportions of renewable energy. Among these renewables, wind energy could play a key role since this is a sector that is growing rapidly and one in which performance is constantly improving. This growth could be further consolidated by the hydrogen sector through the development of storage systems to compensate for the intermittent nature of wind energy. Detailed analyses of the production of hydrogen from wind energy have been carried out over the last several years. While some of the results appear promising, generally speaking the associated costs are far higher than those entailed in producing hydrogen by methane reforming, and to a lesser extent, by coal gasification or water electrolysis using the existing electricity mix (International Energy Agency (IEA), 2005, Bartels et al., 2010 and Protech-H2, 2009). However, it is not always possible to analyze these published results because the assumptions are insufficiently explicit (HyWays, 2007) with regard to production and operating conditions. The aim of the present study, which was conducted in the framework of HyFrance3 (cf. Box 1), is to show that while results clearly depend on the technical and economic assumptions that are made, they also depend to a large degree on the hydrogen demand profiles concerned. While the most obvious case is that of meeting hydrogen demand for hydrogen-powered vehicles in motorway filling stations, we shall also examine more specific profiles that also involve the use of hydrogen as a fuel: a fleet of Hythane®-fueled buses (methane–hydrogen mixture) and a process for producing second-generation biofuels (BtL 2G). Finally, we also present results for a non-transport configuration involving the storage of wind-generated electricity in the form of hydrogen, the aim being to evaluate the interest in such a system in the context of intermittent electricity supply sources.
نتیجه گیری انگلیسی
Overall, the study has shown that the cost of producing hydrogen from wind-generated electricity varied widely depending on the configurations tested. While results quite naturally differed according to the assumptions made concerning the cost and performance of the system components (wind turbines, electrolyzers, hydrogen storage system, etc.), we also showed that costs could differ significantly depending on the demand profiles concerned. Thus, the most favorable costs were found for BtL 2G systems and Hythane® in which hydrogen was produced continuously by connecting the system to the grid, depending on the availability of the wind, without the need for an intermediate storage between production and usage: 4 €/kg, the contribution of wind energy to the production of H2 then accounting for 26%. On the other hand, in the classic case of supplying a filling station, the variability of demand was another factor to add to the variability of the resource, making it necessary to include expensive hydrogen storage facilities in the system and then leading to costs up to ca. 20 €/kg (ca. 7–11 €/kg when connected to the grid, and 50% H2 from wind energy). The wind only hydrogen production cost (“hydrogen when available”) is about 9 €/kg. Although this question has not been examined in the present study, it is clear that technological progress in hydrogen storage will be a key variable. Given the impact of storage volume on the cost of hydrogen production, future reductions in storage costs with the development of large geological storage facilities at wind farms or smaller storage systems near filling stations could lead to a significant drop in the cost of the hydrogen to the end-user. Grid connection, which also helps reduce storage costs by supplementing intermittent wind energy, has a considerable impact on hydrogen production costs. With continuity of supply, storage requirements are reduced (although they cannot be entirely dispensed with where demand is irregular) and the rate of use of electrolyzers can be maximized. In a configuration of this kind, production costs are relatively low (4 €/kg), comparable to usual SMR or grid-connected electrolysis production costs, but the hydrogen is not 100% renewable (26–50% from wind energy). And most importantly, this remains a textbook case, since at present there are no supply contracts enabling hydrogen producers to purchase low-priced electricity as and when necessary to make up for shortages of wind-generated energy. This was not included in our study, but an interesting complementary study would be to evaluate if (or not) the electric transmission system could find a benefit if this kind of contracts was developed. The question to know if it is easier to sell “intermittent electricity” than to buy it still remains open. Last, with the assumptions used in the study, storing electricity in the form of hydrogen is not an economically worthwhile method of compensating for intermittent power generation. The cost of producing the hydrogen and storing it and then converting it back to electricity is still far too high to justify an investment of this order: NPV always remains negative when considering peak/off-peak prices. Besides, there are other technical solutions currently available or under development to facilitate the insertion of intermittent energy into the mix (pumped storage plants, use of fleets of electric vehicles to store energy, remote control of demand, etc.). In current economic conditions, storing wind-generated electricity in the form of hydrogen is not of major interest. On the other hand, in certain conditions, wind-generated electricity could be a promising option for producing hydrogen for use as a fuel in the more general sense (H2, as well as BtL containing H2, and Hythane®).