IEA：要避免气候变化带来的最坏后果，全球能源系统必须大幅减少排放

2020-10-08　 　

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国际能源署（IEA）2020年版能源技术展望指出，要避免气候变化带来的最坏后果，全球能源系统必须大幅减少排放。能源供应、转化和使用都必须实现激进的变革。实现能源和气候目标需要大幅增加可再生能源技术开发和应用，明天需要的可再生能源技术取决于今天的创新。电力不能解决全部经济的去碳化。电力和重工业等行业现有资产的排放挑战最大。市场在动用资金和促进创新上至关重要，但不能凭此就能实现净零排放，政府需要发挥决定性作用。






2020年版能源技术展望评估了现有能源基础设施的存量在剩余生命周期内（2019-2070年）的二氧化碳排放总量。根据这份报告，世界范围内使用的能源生产、运输和消费设施如果不提前退役或者加上减排设备的话，从现在到2070年累计碳排放近7500亿吨，将耗尽联合国的温升不超过2°C目标所剩余的二氧化碳预算。因此，如何处理现有的能源和碳排放的基础设施对于实现巴黎协定的气候承诺至关重要。






具体来看，现有能源相关基础设施累积排放的大部分预计将来自来自电力（55%）和重工业（26%）行业，交通运输占11%左右（其中三分之二来自公路运输），建筑业占3%。电力行业约80%的预期累积排放量将来自煤电厂。到2050年，现有燃煤电厂的年排放量将达到59亿吨，接近当前水平的70%。到2070年，约75%的电力部门累计排放量是与亚洲煤电厂相关，仅中国就占了近50%的累积二氧化碳排放量。




现有能源设施的在未来的碳排放与其寿命相关。以发电领域为例，在美国，现有煤电厂平均年龄超过40年，欧洲约35年，而大多数亚洲国家低于20年，在中国才13年。中国大约50%的现有火电在过去10年内投运，85%的容量在过去的20年里投运。在目前全球2100吉瓦的现有燃煤发电装机容量（外加167吉瓦在建容量）中，到2050年仍有1440吉瓦继续运行，其中900吉瓦在中国。相比之下，燃气发电厂寿命较短。现有的全球1800吉瓦燃气发电装机中（外加在建的110吉瓦），到2050年只有350吉瓦仍在继续运行。工业是现有基础设施排放的另一个主要碳排放源。由于能源密集度高，化石燃料在能源使用中所占的比重很大，而且生产设备相对较长的使用寿命。预期的1960亿吨工业累积排放量中，钢铁和水泥子行业各占30%左右，化工子行业约占15%，制造业和其他部门占25%。
  
报告英文执行摘要如下：       
Executive Summary
Achieving our energy and climate goals demands a dramatic scaling up of clean energy technologies


To avoid the worst consequences of climate change, the global energy system must rapidly reduce its emissions. Calls to reduce global greenhouse gas emissions are growing louder every year, but emissions remain at unsustainably high levels. International climate goals call for emissions to peak as soon as possible and then decline rapidly to reach net-zero in the second half of this century. The vast majority of global CO2 emissions come from the energy sector, making clear the need for a cleaner energy system. Global CO2 emissions are set to fall in 2020 because of the Covid-19 crisis, but without structural changes to the energy system, this decline will be only temporary.  


Achieving net-zero emissions requires a radical transformation in the way we supply, transform and use energy. The rapid growth of wind, solar and electric cars has shown the potential of new clean energy technologies to bring down emissions. Net-zero emissions will require these technologies to be deployed on a far greater scale, in tandem with the development and massive rollout of many other clean energy solutions that are currently at an earlier stage of development, such as numerous applications of hydrogen and carbon capture. The IEA’s Sustainable Development Scenario – a roadmap for meeting international climate and energy goals – brings the global energy system to net-zero emissions by 2070, incorporating aspects of behavioural change alongside a profound transformation in energy system technology and infrastructure.  
This report analyses over 800 technology options to examine what would need to happen for the world to reach net-zero emissions by 2050. The report focuses primarily on the Sustainable Development Scenario, but it also includes a complementary Faster Innovation Case that explores the technology implications of reaching net-zero emissions globally by 2050. The analysis seeks to assess the challenges and opportunities associated with a rapid, clean energy transition. The report covers all areas of the energy system, from fuel transformation and power generation to aviation and steel production.


Electricity cannot decarbonise entire economies alone


Hydrogen extends electricity’s reach. On top of the surging demand for electricity from across different parts of the economy, a large amount of additional generation is needed for low-carbon hydrogen. The global capacity of electrolysers, which produce hydrogen from water and electricity, expands to 3 300 GW in the Sustainable Development Scenario, from 0.2 GW today. In order to produce the low-carbon hydrogen required to reach net-zero emissions, these electrolysers would consume twice the amount of electricity the People’s Republic of China generates today. This hydrogen forms a bridge between the power sector and industries where the direct use of electricity would be challenging, such as in the production of steel from iron ore or fuelling large ships. 


Carbon capture and bioenergy play multifaceted roles. Capturing CO2 emissions in order to use them sustainably or store them (known as CCUS)1 is a crucial technology for reaching net-zero emissions. In the Sustainable Development Scenario, CCUS is employed in the production of synthetic lowcarbon fuels and to remove CO2 from the atmosphere. It is also vital for producing some of the low-carbon hydrogen that is needed to reach net-zero emissions, mostly in regions with low-cost natural gas resources and available CO2 storage. At the same time, the use of modern bioenergy triples from today’s levels. It is used to directly replace fossil fuels (e.g. biofuels for transport) or to offset emissions indirectly through its combined use with CCUS. 
A secure and sustainable energy system with net-zero emissions results in a new generation of major fuels. The security of today’s global energy system is underpinned in large part by mature global markets in three key fuels – coal, oil and natural gas – which together account for about 70% of global final energy demand. Electricity, hydrogen, synthetic fuels and bioenergy end up accounting for a similar share of demand in the Sustainable Development Scenario as fossil fuels do today.


The clean energy technologies we will need tomorrow hinge on innovation today


Quicker progress towards net-zero emissions will depend on faster innovation in electrification, hydrogen, bioenergy and CCUS. Just over one‑third of the cumulative emissions reductions in the Sustainable Development Scenario stem from technologies that are not commercially available today. In the Faster Innovation Case, this share rises to half. Thirty-five percent of the additional decarbonisation efforts in the Faster Innovation Case come from increased electrification, with around 25% coming from CCUS, around 20% from bioenergy, and around 5% from hydrogen.


Long-distance transport and heavy industry are home to the hardest emissions to reduce. Energy efficiency, material efficiency and avoided transportation demand (e.g. substituting personal car travel with walking or cycling) all play an important role in reducing emissions in long-distance transport and heavy industries. But nearly 60% of cumulative emissions reductions for these sectors in the Sustainable Development Scenario come from technologies that are only at demonstration and prototype stages today. Hydrogen and CCUS account for around half of cumulative emissions reductions in the steel, cement and chemicals sectors. In the trucking, shipping and aviation sectors, the use of alternative fuels – hydrogen, synthetic fuels and biofuels – ranges between 55% and 80%. Highly competitive global markets, the long lifetime of existing assets, and rapidly increasing demand in certain areas further complicate efforts to reduce emissions in these challenging sectors. Fortunately, the engineering skills and knowledge these sectors possess today are an excellent starting point for commercialising the technologies required for tackling these challenges.


Emissions from existing assets are a pivotal challenge


Power and heavy industry together account for about 60% of emissions today from existing energy infrastructure, climbing to nearly 100% in 2050 if no action is taken.Reaching net-zero will depend on how we manage the emissions challenge presented by these sectors’ long-lasting assets, many of which were recently built in Asian economies and could operate for decades to come. The situation underscores the need for hydrogen and CCUS technologies. Ensuring that new clean energy technologies are available in time for key investment decisions will be critical. In heavy industries, for example, strategically timed investments could help avoid around 40% of cumulative emissions from existing infrastructure in these sectors.


CO2 emissions reductions in the energy sector in the Sustainable Development Scenario relative to the Stated Policies Scenario 






Governments will need to play the decisive role
While markets are vital for mobilising capital and catalysing innovation, they will not deliver net-zero emissions on their own. Governments have an outsized role to play in supporting transitions towards net-zero emissions. Long-term visions need to be backed up by detailed clean energy strategies involving measures that are tailored to local infrastructure and technology needs. Effective policy toolkits must address five core areas:
Tackle emissions from existing assets


Strengthen markets for technologies at an early stage of adoption


Develop and upgrade infrastructure that enables technology deployment


Boost support for research, development and demonstration


Expand international technology collaboration.


Economic stimulus measures in response to the Covid-19 crisis offer a key opportunity to take urgent action that could boost the economy while supporting clean energy and climate goals, including in the five areas above.
（部分中文内容引用自国际能源小数据微信公众号）


来源：中外能源经济观察
作者：IEA