تجزیه و تحلیل سناریوی انرژی اقتصادی از سوخت های جایگزین برای حمل و نقل شخصی با استفاده از مدل مارکال چند منطقه ای جهانی (GMM)

This paper deals with the long-term prospects of alternative fuels in global personal transport. It aims at assessing key drivers and key bottlenecks for their deployment, focusing particularly on the role of biofuels and hydrogen in meeting climate policy objectives. The analysis is pursued using the Global Multi-regional MARKAL model (GMM), a perfect foresight “bottom-up” model of the global energy system with a detailed representation of alternative fuel chains, linked to the Model for the Assessment of Greenhouse Gas Induced Climate Change (MAGICC). The analysis shows that biofuels are limited by the regional availability of low-cost biomass, but can be important for meeting mild climate policy targets. If policy-makers intend to pursue more stringent climate policy, then hydrogen becomes a competitive option. However, the analysis finds that the use of hydrogen in personal transport is restricted to very stringent climate policy, as only such policy provides enough incentive to build up the required delivery infrastructure. An analysis of costs additionally shows that “keeping the hydrogen option open” does not take considerable investments compared to the investment needs in the power sector within the next decades, but allows the use of hydrogen for the pursuit of stringent climate policy in the second half of the century.

Global primary energy consumption in the year 2005 was almost 480 EJ, up from 229 EJ in the year 1971 [1]. Historically, this has been supplied primarily by fossil fuels, namely coal, oil and natural gas, which today account for approximately 81% of total primary energy supply, despite some growth in nuclear and renewables. According to the International Energy Agency (IEA) [1] as well as the US Energy Information Administration (EIA) [2], a continuation of current trends is likely to increase global primary energy demand to approximately 740 EJ by the year 2030, driven by strong growth in China and India and despite the impact of a number of policy measures expected to be taken in OECD countries.1 The transport sector – and in particular personal transport – plays a pivotal role in these energy consumption trends, mainly due to two key factors. First and foremost, it relies almost entirely on one fossil resource alone, i.e. petroleum and its products. Petroleum supplies 95% of the total energy used by world transport [3], and this high reliance on petroleum fuels translates into high CO2 emissions as a result of the combustion process. The transport sector produced about 6.3 GtCO2 emissions in 2005, or 23% of global energy-related CO2 emissions [4], and the total amount of transport-related CO2 emissions has more than doubled over the past almost 40 years (2.8 GtCO2 in 1971). The problem of CO2 emissions from transport is likely to increase in the future as a result of the second key problem in transportation: the global demand for transport is projected to increase strongly in the decades to come as a result of economic development and growth [2] and [5]. Much of the growth is anticipated to take place in the developing world, notably in growing economies such as China, India or Brazil. Goldman Sachs expects China and India to emerge as the world's leading car markets, overtaking the United States in 20 (China) to 30 (India) years [6]; whereas the IEA projects that China will overtake the United States as the largest car market in the world even sooner, by 2015 [1]. The described developments are very likely to exacerbate the impacts on global climate change, as suggested by the latest report of the Intergovernmental Panel on Climate Change (IPCC) [7]. As a consequence, responding to the challenge of satisfying increased demand for energy and mobility, while at the same time combating climate change and maintaining and improving current levels of energy security, is high on the agenda of policy-makers. As a means for tackling this challenge, alternative fuels such as hydrogen and biofuels have been advocated as potential substitutes for petroleum fuels in personal transport, but there is still a considerable need for an understanding of drivers and bottlenecks for their deployment. This paper aims at contributing to this understanding by looking into two key questions: - What is the impact of pursuing different climate policy targets on the prospects of alternative fuels for reducing global CO2 emissions from personal transport? - What are key drivers and key bottlenecks for the deployment of alternative fuels, in particular for hydrogen? The analysis is pursued using the Global Multi-regional MARKAL model (GMM), which depicts the global energy system as a whole recognising that although transport will need to play a pivotal role, energy system efforts will be needed to fully address climate change mitigation. GMM and its model features are introduced in Section 2. Section 3 presents the baseline scenario, which provides important insights regarding the extent of the challenge, and a frame of reference against which the impacts of climate policy can be assessed. In Section 4, the implications of pursuing different climate policy targets on the role of alternative fuels in personal transport are analysed. The analysis is complemented by a discussion of the sources of hydrogen production for selected scenarios, where hydrogen market penetration takes place, as well as an analysis of hydrogen delivery infrastructure as a potential bottleneck for hydrogen market penetration. Finally, Section 5 derives conclusions and policy implications.

The analyses conducted in this paper explored the implications of different climate policy targets on cost-optimal fuel choices in personal transport. In addition, bottlenecks for their implementation were investigated, with a special focus on hydrogen. The analyses found that climate policy targets generally spur the deployment of hydrogen and biofuels. Biofuels are a particularly cost-effective option for meeting mild climate policy targets, consistent with findings of other authors such as Turton [45]. The results obtained here, however, indicate that there is no one optimal way of utilizing biomass. In a future sustainable energy system, biomass is likely to become an important energy carrier, and its importance is increasing with increasing climate policy targets. Biofuels can have a role in personal transport; but the degree of their utilization depends on the one hand on the availability of sustainable produced low-cost biomass, an issue which has been widely debated recently in the context of competition with agricultural land-uses for food production and increasing food prices, potentially induced by an increasing utilization of biofuels [46] and [47]. For some world regions, which lack abundant and cheap biomass resources, an increased utilization may also result in an increased need for biofuels imports. On the other hand, the extent to which biofuels can become a competitive option for transport is linked to whether and when hydrogen can be developed as a transportation fuel. The present analysis suggests that the scarce biomass resources are better utilized to reduce CO2 emissions in electricity and heat production under the assumptions applied here, and similar to observations of other authors [48] and [49]. In such scenarios, biofuels are found to act as bridging option until hydrogen fuel cells become competitive in personal transport. Hydrogen production was found to react strongly to climate policy targets, and the more stringent the target, the more hydrogen is deployed. The analysis with GMM looked closely into hydrogen production technologies and infrastructures for hydrogen delivery. It was found that one key to the deployment of hydrogen in the first place is the availability of low- or zero-emissions technologies for hydrogen production, and coal gasification with carbon capture and storage (and electricity co-production) was identified as a highly promising technology in this regard, along with nuclear hydrogen production and wind power parks dedicated to hydrogen production via electrolysis. The other key to a successful deployment of hydrogen is the build-up of a network for hydrogen delivery. An analysis of minimum investment levels for hydrogen infrastructures along with a maximum number of installations per decade showed that the possibility to quickly expand large-scale hydrogen distribution networks is a pre-requisite for hydrogen deployment. It was found that limitations to the rate at which a hydrogen distribution network can be constructed may be a bottleneck for hydrogen deployment and may prevent market penetration of hydrogen fuel cells. Very stringent climate policy, however, was found to promote alternative hydrogen production and delivery modes, in particular forecourt hydrogen, thereby facilitating the deployment of fuel cells in personal transport. Any limitation to the deployment of hydrogen delivery networks, however, leads to higher overall energy system cost. The analyses pursued in this paper have identified technology and fuel options that are cost-optimal to meet the climate policy targets and explored barriers to their implementation. Throughout all scenarios, it was found that alternative fuels can play a role in future transport to a greater or lesser extent, depending on the scenario investigated. Clearly, however, there is a considerable degree of uncertainty involved in such an assessment, and technology breakthrough not considered in this analysis such as in cost and performance of batteries could alter the picture in favour of other fuels, i.e. electricity. Moreover, there are many more obstacles to overcome for the deployment of clean alternative fuels in transport than those being investigated here, and policy targets do not necessarily induce the changes that are desired by policy-makers. By way of an example [50] review experiences with US legislation during the 1990s and discuss why the Energy Policy Act of 1992, which established a goal for alternative fuel use of 10% by the year 2000, and 30% by 2010, did not achieve the desired outcome. The developments of alternative fuel use have by far fallen short of these targets, despite significant financial and policy investments. The authors identify several reasons for this development, among others a chicken-or-egg problem with the development of a refuelling infrastructure. More significantly, however, the industry with a significant stake in petroleum fuels and vehicle technologies responded by implementing significant improvements for conventional fuels and vehicles, thus delivering significant emission reductions and weakening the policy argument. Moreover, alternative fuels failed to develop out of niche market applications into the mainstream, despite heavy government support. Such experiences show the extent of the challenge facing biofuels as well as hydrogen. It is not only technology development, such as achieving low-cost fuel cells with US$ 50/kW that are needed to make new technologies economically viable. It is also an appropriate policy environment that is required to facilitate a switch to alternative fuels, together with industry involvement, e.g. public private partnerships, particularly given the large investment needs discussed in this paper. One key lesson from past experiences is that promoting the adoption of alternative fuels in transport is an effort that requires involving all stakeholders; otherwise, existing infrastructure lock-ins are hard to break and replace. A good example for such a collaborative effort is the development of a hydrogen-fuelled economy in Iceland, where several industrial players are collaborating with academia and policy-makers to gain experiences with the application of hydrogen fuel cells in buses and with the development of a hydrogen infrastructure. Such projects represent precisely the type of niche applications that are needed to develop hydrogen further, similar to what was found in the above analysis. The findings of the analyses in this paper support the notion that policy-makers need to work on two fronts at a time if they intend to deal with the energy system challenges associated with climate change. First, they need to provide the required RD&D programmes to support the development of biofuels as a transition fuel in personal transport. Additionally, an appropriate regulatory framework could help increasing the share of biofuels in transport, e.g. by invoking minimum shares of biofuels in transport as recently done in the European Union for the year 2020 [51], or by setting a minimum standard for biofuels blends into conventional fuels.12 Such policy action could support overcoming existing infrastructure lock-ins in transport fuel supply and gain experiences with the deployment of alternative fuels. In addition, policy-makers need to further support research on hydrogen and fuel cells, particularly through the implementation of demonstration projects. Technologies that require particular attention in this light appear to be hydrogen fuel cells, both for mobile and stationary applications; and hydrogen production technologies, in particular involving gasification, but also electrolytic hydrogen production which could entail spillover effects on a more widespread use of renewable energies in the electricity sector by providing storage capacity to intermittent resources.13 Ideally, such research projects are realized as efforts involving all the various stakeholders involved, ranging from industry to academia and politics, but also consumers for gaining insights into the implications of hydrogen use in daily applications and the satisfaction of consumers with the “commodity hydrogen”. Early involvement of all stakeholders allows minimizing the risk of failure when it comes to the actual market introduction of hydrogen in the transport sector. A combination of such policy measures addressing both biofuels and hydrogen simultaneously can help spur the use of biofuels as a transition fuel until the feasibility of reducing hydrogen fuel cell costs is better understood and first experiences with hydrogen on a pilot project level have been gained. In any case, hydrogen appears likely to be a long-term option for transport under the assumptions in our analysis, as it represents a radical departure from today's transport fuel chains, and there is still a considerable need for RD&D and an analysis of the potential of individual technologies, in particular fuel cells. However, facilitating hydrogen requires efforts today: the analysis presented here showed that for realizing stringent climate policy targets, investment needs for gaining experiences with hydrogen production technologies and setting up pilot projects with an appropriate hydrogen supply infrastructure are high. Nevertheless, the scale of the effort over the next 50 years is small compared to the additional investment needs required in the power sector, and would allow us to “keep the hydrogen option open” for the second half of the century, thus potentially allowing future generations to reduce CO2 emissions drastically and satisfy transport demand in a more sustainable manner than today.