蓝氢（英文版）.pdf

ALEX ZAPANTIS General Manager, Commercial APRIL 2021 BLUE HYDROGENBLUE HYDROGEN 2 Acknowledgements This research was overseen by an Advisory Committee of eminent individuals from government, academia and industry with deep expertise across technology, policy, economics and finance relevant to climate change. The guidance of the Advisory Committee has been invaluable in developing this work. Thanks are also due to the Center for Global Energy Policy at Columbia University SIPA for their review and input to this report. Advisory Committee for the Circular Carbon Economy: Keystone to Global Sustainability Series Mr. Brad Page, CEO, Global Carbon Capture Remove. Remove includes measures which remove CO 2 from atmosphere or prevent it from entering the atmosphere after it has been produced such as carbon capture and storage (CCS) at industrial and energy facilities, bio-energy with CCS (BECCS), Direct Air Capture (DAC) with geological storage, and afforestation. This report explores the potential contribution of blue hydrogen, which has very low life-cycle CO 2 emissions, to climate mitigation. Blue hydrogen produced from fossil fuels with carbon capture and storage (CCS) can contribute to the Reduce dimension of the CCE by displacing the use of unabated fossil fuels in industrial and energy applications. Hydrogen produced from biomass with CCS can also contribute to the Remove dimension of the CCE as it has negative life-cycle emissionsBLUE HYDROGEN 5 Near-zero emissions hydrogen (clean hydrogen) has the potential to make a significant contribution to emissions reduction in the power generation, transportation, and industrial sectors. Hydrogen can be burned in turbines or used in fuel cells to generate electricity, can be used in fuel cells to power electric vehicles, as a source of domestic and industrial heat, and as a feedstock for industrial processes. Hydrogen may also be used to store excess energy generated by intermittent renewable electricity sources when supply exceeds demand, albeit with significant losses. The virtue of hydrogen is that it produces zero carbon emissions at the point of use. Currently approximately 120Mt of hydrogen is produced annually; around 75Mt of pure hydrogen with the remainder being mixed with other gases, predominantly carbon monoxide (CO) in syngas (synthesis gas). The pure hydrogen is used mostly in refining (39Mt) and ammonia production (33Mt). Less than 0.01Mt of pure hydrogen is used in fuel cell electric vehicles. The syngas containing the remaining 45Mt of hydrogen is used mostly in methanol production (14Mt), direct reduction iron making and other industrial processes including as a source of high-heat (IEA 2019; International Energy Agency (IEA) 2020 2020a). Approximately 98% of current hydrogen production is from the reformation of methane or the gasification of coal or similar materials of fossil-fuel origin (eg petcoke or ashphaltene). Only about 1% of hydrogen production from fossil fuels includes carbon capture and storage (CCS). Approximately 1.9% of hydrogen is produced as a bi-product of chlorine and caustic soda production. The International Energy Agency (IEA) estimates that less than 0.4% of hydrogen is produced by the electrolysis of water powered by renewable electricity. Approximately 98% of global hydrogen production is emissions intense, emitting around 830Mtpa of CO 2 (IEA 2019; Global CCS Institute 2020). Low emission production methods for hydrogen available today include steam methane reformation (SMR), autothermal reformation of methane (ATR), or coal gasification; each with carbon capture and storage (CCS), and electrolysis of water powered by near zero emissions electricity such as renewable generation or nuclear power. Production of clean hydrogen from biomass through anaerobic digestion, fermentation, gasification or pyrolysis (all with CCS) are at earlier stages of commercialization. Production from biomass with CCS is attractive as it would deliver negative emissions, although it would compete with other sources of demand for biomass (International Energy Agency (IEA) 2020 2020a). Figure 2. shows estimates of the emission intensity of various hydrogen production pathways. The production pathways with the highest emissions are coal gasification without CCS, and electrolysis using power supplied by fossil generators; in this example, natural gas combined cycle generation (NGCC). Both have an emissions intensity of approximately 22kgCO 2 /kgH2. Further, using electricity from a power grid to increase the utilisation of renewable powered electrolysers will also produce high emissions hydrogen, unless the grid has an extremely low emissions intensity. If the grid has an emissions intensity equivalent to NGCC (400kg/MWh), and 63% of the power supplied to the electrolysers is from the grid (the remaining 37% being from dedicated renewable generation), the hydrogen produced will have an emissions intensity of approximately 14kgCO 2 / kgH2 this compares to approximately 9-10kgCO 2 / kgH2 for conventional SMR without CCS. A significant conclusion from this analysis is that electrolysers should never be powered by electricity from a grid supplied by fossil generation. Hydrogen produced by electrolysers will produce higher CO 2 emissions than conventional SMR without CCS unless the electricity supplying the electrolyser has an emission intensity of around 165kgCO 2 /MWh or less. 1 1.0 CURRENT PRODUCTION Bruce et al. 2018; International Renewable Energy Agency 2019; Hydrogen Council 2020) ALL COSTS IN USD PER KG OF HYDROGEN DEDICATED RENEWABLE ELECTRICITY SUPPL Y OTHERWISE CURTAILED RENEWABLE ELECTRICITY SUPPLY STEAM METHANE REFORMATION WITH CCS BLACK COAL GASIFICATION WITH CCS CSIRO 2018 3 $7.70 (35% capacity factor, electricity price 6c/kWh) $18.20 (10% capacity factor, electricity price 2c/kWh) $1.60 - $1.90 (Gas price is $8/GJ) $1.80 - $2.20 (Coal price is $3/ GJ) IEA 2020 $2.30 $6.60 4 (Low end is 57% capacity factor and electricity cost 2c/kWh. High end is 57% capacity factor and electricity cost 10c/kWh) N/A $1.40 $2.40 (Low end is gas price $3/GJ. High end is gas cost $9/GJ) $2.05 - $2.20 (Low end is coal price 43c/GJ. High end is coal cost $1.15/GJ) IRENA 2019 $2.70 $6.90 (Low end is wind; 48% capacity factor 26% capacity factor USD2.30/kg to USD7.70/kg of hydrogen. The largest contribution to that variation arises from the assumed utilisation of the electrolyser (ie, capacity factor of the dedicated renewable generation capacity), the price of electricity and the capex for the electrolyser which is predominantly a function of scale (larger are lower capex per unit production capacity).BLUE HYDROGEN 12 Figure 4. Simple average and range of estimated current cost of clean hydrogen production from recently published reports.(International Energy Agency (IEA) 2020 2020b)(International Renewable Energy Agency 2019) (Hydrogen Council 2020)(Bruce et al. 2018) (only one estimate of cost of curtailed renewable with electrolysis). SMR = steam methane reformation. CCS = carbon capture Naterer, Jaber Mehmeti et al. 2018). Hydrogen produced by electrolysis will only be clean if it is powered by renewable energy or nuclear power (see figure 2.). Renewable hydrogen requires sufficient land to host the wind and/or solar PV generation capacity whilst fossil hydrogen with CCS requires land for CO 2 pipelines and injection infrastructure. Fossil hydrogen with CCS also requires coal or gas and pore space for the geological storage of CO 2 . The AREH project in Australias remote north-west plans to produce 10 million tonnes per year of ammonia. This requires approximately 1.76Mtpa of hydrogen which will be produced by the electrolysis of water powered by a combined 23GW of solar PV and wind capacity, located on 5750km2 of land (The Asian Renewable Energy Hub 2020b). AREH benefits from excellent solar and wind resources that together will achieve an expected capacity factor of approximately 48%. AREH also benefits from the availability of abundant land with very low opportunity cost. This combination of resources, together with scale, could deliver near-zero emissions hydrogen, towards the lower end of costs for renewable hydrogen (see Figure 4.). Where abundant low-cost land or excellent renewable resources are not available, but coal or gas and pore space for geological storage of CO 2 is, clean hydrogen from gas or coal with CCS will be the best option. Compared to renewable hydrogen, clean hydrogen produced from gas or coal with CCS requires very modest amounts of land and electricity. For example, production of 1.76Mt of hydrogen (equivalent to one AREH project) from steam methane reformation with CCS would require approximately 14km2 of land, assuming a 500km CO 2 pipeline in a 20m wide corridor, 2km2 for the plant, and four CO 2 injection wells situated over a 2km2 area. Figure 8. compares resource requirements for renewable hydrogen based on the AREH project to the same quantity of hydrogen produced from gas or coal with CCS. 7.0 RESOURCE REQUIREMENTS FOR CLEAN H2 PRODUCTION 6 Total project area is 6,500km2 , including an additional 3GW of wind and solar PV capacity which will be dedicated to electricity production for exportBLUE HYDROGEN 19 Figure 8. Resources required for the production of 1.76Mt of H2 from coal or gas with CCS and electrolysis powered by renewable electricity. Land requirements for electrolysis pathway is taken from the AREH Project website. Assumes combined 48% capacity factor for wind and solar PV and 55kWh/kg of H2 via electrolysis (IEA 2019). 9kg water required per kg of H2 for electrolysis (IEA 2019). Electricity requirement for CG+CCS (3.48kWh/ kgH2 ) and SMR+CCS (1.91kWh/kgH2 ) includes electricity used in the production of the coal or gas (Mehmeti et al. 2018). 6.3kg of water required per kg of H2 for SMR with CCS (Naterer, Jaber & Dincer 2010). 9kg water required per kg of H2 for coal gasification with CCS (Bruce et al. 2018). Land requirement for CG+CCS and SMR+CCS assumes 500km CO 2 pipeline in a 20m wide corridor, 2km2 for the plant and 10 injection wells over 5km2 for CG+CCS, and 4 injection wells over 2km2 for SMR+CCS. CO 2 captured requiring geological storage per kg of H2 is 21.5kg for CG+CCS and 7.2kg for SMR+CCS. 9 9BLUE HYDROGEN 20 As noted previously, the production of blue hydrogen requires access to coal or gas and access to pore space for the geological storage of CO 2 . Both the coal and gas industries are mature with well-established supply chains. Accessing sufficient supplies of coal or gas to support blue hydrogen production in any prospective location will be a routine process that needs no discussion in this report. Accessing pore space for geological storage of CO 2 however is not yet routine. This raises the question as to whether the availability of geological storage resources is a significant constraint on the production of blue hydrogen. Another report in this series (on CCS Hubs and Clusters) addresses this question for CCS in any industry. A conclusion from that analysis is that global resources for the geological storage of CO 2 are more than sufficient for CCS to play its full role under any climate mitigation scenario. The opportunity lies in identifying locations where all the requisites of blue hydrogen production are available. For example, locations with access to coal or gas as well as pore space for CO 2 storage. The Hubs and Clusters Report identifies many such locations around the world. Figure 9 below provides a summary of an estimate of global geological storage resources for CO 2 . It is clear that pore space for the geological storage of CO 2 is not a constraint on blue hydrogen production, although locating production centres relatively close to storage resources will minimise CO 2 transport costs. Figure 9. Estimate of Global CO 2 Geological Storage Capacity in Billions of Tonnes. Confidence is a measure of the maturity of storage resource appraisal.BLUE HYDROGEN 21 As shown previously, low-emissions hydrogen provides an opportunity to deliver emissions abatement at the multi-gigatonne scale if sufficient volumes are utilised in place of unabated fossil fuels. However, as the objective is to reduce all anthropogenic emissions to net-zero, it is appropriate to examine how the production of low emission hydrogen would impact upon the broader emissions abatement challenge. Producing hydrogen using electrolysers requires large amounts of electricity. To illustrate, producing 530Mt of clean hydrogen, the amount the Hydrogen Council projected could be utilised in 2050, would require 29,000TWh of near-zero emissions electricity. This is more than the total global generation of electricity by all sources in 2018 (International Energy Agency (IEA) 2020). That quantity of near zero emissions electricity could theoretically completely replace all fossil generation capacity resulting in a global zero emissions (at point of generation) electricity system. A legitimate question is whether there is an emissions abatement opportunity cost associated with using renewable electricity (or nuclear generation) to produce hydrogen instead of displacing unabated coal or gas electricity generation. Assuming that the clean hydrogen displaces the combustion of natural gas, that emissions abatement opportunity cost can be very significant because: Around 30% of the energy is lost in the process of converting electricity to hydrogen via electrolysis. Coal has a much higher emission factor than natural gas (90.23 kgCO 2 e/GJ vs 51.53kgCO 2 e/GJ). Almost twice as much abatement is accrued by displacing coal compared to methane per unit energy. Coal or gas fired power stations have a thermal efficiency of around 30 50%. Displacing one GJ of electricity production from a coal or gas power plant prevents emissions from the combustion of 2-3GJ of coal or gas. The ratio of emissions abatement from direct use of renewable electricity to displace grid electricity, to emissions abatement from the displacement of natural gas by hydrogen produced using the same quantity of renewable electricity can be calculated as follows. Where: Er Ac 8.0 EMISSIONS ABATEMENT OPPORTUNITY COST OF RENEWABLE HYDROGEN 7 Assuming 55kWh of electricity is required to produce 1kg of H2 8 Assuming there was sufficient dispatchable near zero emissions generating capacity such as nuclear and hydroelectric plus renewable generation and energy storage to ensure supply = Energy value of the renewable electricity in GJ = emission abatement if renewable electricity is used to displace grid electricity in tonnes CO 2 eBLUE HYDROGEN 22 Ag PEMeff EFc EFg Substituting for variables: This relationship is graphed in Figure 10 for electricity production with emissions intensity up to 1.1tCO 2 /MWh (305kgCO 2 /GJ), which is equivalent to German lignite fired generation. Renewable electricity delivers three times more emissions abatement when used to displace NGCC g