Abstract
Steam-electric power dominates global electricity production. Mitigating its environmental burdens relies on quantifying them globally, on a high resolution. Here, with an unprecedented combination of detail and coverage, the Rankine cycle was individually modelled for >21 000 geocoded steam-electric generating units globally. Accounting for different cooling systems and fuels enabled the calculation of three major environmental stressors on a generating unit level. Geographical, chronological, and technological patterns are examined, as are trade-offs and improvement scenarios. Greenhouse gases (GHG) emissions from young (>2000) Chinese coal-fuelled generating units are equal to the sum of GHG emissions from all steam-electric power plants of all ages in the U.S. and Europe, and occupy 5% of all GHG emissions from the entire global economy. Twenty-four per cent of freshwater consumed from steam-electric power originates from nuclear power units from the 1970s/1980s, mainly in the U.S. and Europe. One per cent of steam-electric generating units is responsible for 50% of global heat emissions to freshwater. The median carbon intensity of Indian coal-fired units (≥50 MW) is 7%–16% higher than that in any other region globally. As concerns GHGs, technology-related efficiency differences (Rankine cycle, cooling system) play a small role compared to the fuel, which dominates the carbon intensity (GHGs/GJ el.). With the highest shares of cogeneration, 1 GJ electricity from tower-cooled coal units in Russia consumes on average 8%–49% less freshwater compared to respective units globally. There is a small margin for improvement based on alternative steam-electric technologies: retiring inefficient units and replacing their demand by ramping up more efficient ones with the same fuel, within the same country results in, respectively, ∼1%, 6%, and 11% fewer GHG emissions, freshwater consumption, and heat emissions globally. The full environmental benefits of completely retiring old units (<1970) consist of 9% fewer GHG emissions, 7% less freshwater consumed, and 18% fewer thermal emissions globally.
Highlights
Greenhouse gases (GHG) emissions from young (>2000) Chinese coal-fuelled generating units are equal to the sum of GHG emissions from all steam-electric power plants of all ages in the U.S and Europe, and occupy 5% of all GHG emissions from the entire global economy
3.1 Geographical, chronological, and fuel-specific analysis of stressors A striking observation involves the magnitude of GHG emissions from coal-fuelled Chinese generating units entering commercial operation from 2000 onwards (figures 1(a) and S15): the GHG emissions occurring in 2012 from these young Chinese coalfuelled units alone are equal to the GHG emissions from the entire cohort of steam-electric power plants of all ages in the U.S and Europe together, occupying a share of 26% of the global GHG emissions from the steam-electric power sector, and 5% of all GHG emissions from the entire global economy, as estimated by the EDGAR database [39, 40]
This work presents a comprehensive environmental burden analysis with an unprecedented combination of the highest level of detail and coverage of the global steam-electric power sector, offering the most detailed dataset to date relating to three important environmental stressors, GHG emissions, freshwater consumption, and thermal emissions to freshwater
Summary
Modern lifestyles are inextricably dependent on the use of electricity. A growing population equates to a growing electricity demand, with projections of electricity generation expected to increase by approximately 68% by 2040 compared to 2010 levels [1]. Steam-electric power production occupies the unique and unfavourable spot of ticking one, two, or all three of the following triad of environmental stressors: emissions to air, thermal emissions to water, and water consumption, depending on the combination of fuel and cooling system used (table 1), all of which have environmental impacts with local or global outreach. The heat contained in once-through cooling effluents can lead to extended stretches of thermally polluted rivers and lakes, compromising the habitats of aquatic organisms [5–10]. To put these impacts into context, the WEF Global Risks Report 2020 [11], a result of a multistakeholder process, lists climate action failure, biodiversity loss and water crises among the top five most impactful global risks. Freshwater consumption and heat emissions contribute to water crises and biodiversity loss, while carbon footprints constitute an indicator for assessing the climate crisis
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