Life Cycle Overview

In developed nations, energy infrastructure is largely in the background of society, providing reliable energy with little consumer awareness. Thus, it is difficult to appreciate how energy is produced from various technologies or how the climate or environmental are impacted by these technologies. Compiled below is a brief overview of lifecycle environmental impacts of coal, wind, solar, and battery technologies for the production of electricity. 

Coal

The table below describes major environmental impacts over the life cycle of coal energy. It encompasses impacts from coal mining, combustion, and waste. For coal energy to contribute significantly and sustainably to power society, the greenhouse gas emissions that result from coal combustion must be prevented. There are various technologies that enable fossil fuel combustion with minimal, zero, or net negative emissions. Staged Pressurized Oxy-Combustion is one such technology specially designed for coal combustion that is currently being developed by the CCCU; we will assume SPOC technology in the coal life cycle. A brief description of SPOC technology is provided in the Discussion section. 

Wind

The table below describes major environmental impacts over the life cycle of wind energy. It encompasses Rare Earth Element extraction and refining, land use, and turbine blade waste impacts. Since wind energy resources are intermittent, battery technology is required for wind energy systems to produce usefully reliable energy if no other dispatchable backup (e.g. fossil fuel, nuclear, etc.) is used to manage intermittency. As a result, the life cycle environmental impacts of wind energy include those of battery technologies. 

Solar

The table below describes major environmental impacts over the life cycle of solar energy. It encompasses impacts from material extraction for thin-film technologies, manufacturing hazards for silicon-based panels, and waste disposal. Like wind energy, solar resources are intermittent, and battery technology is required for solar energy systems to produce usefully reliable energy if no other dispatchable backup (e.g. fossil fuel, nuclear, etc.) is used to manage intermittency. As a result, the life cycle environmental impacts of solar energy include those of battery technologies. 

Batteries

The table below describes major environmental impacts across the life cycle of Lithium-Ion Batteries (LIBs). It encompasses issues with lithium and other metal extraction, and issues of waste disposal and recycling. The purpose of battery technology is to manage the intermittency of renewable energy sources (e.g. wind, solar) to enable renewables to produce energy of similar reliability to fossil fuel energy. 

Discussion

Land Use Magnitudes

The magnitude of required land use are significantly greater for renewable technologies (wind, solar) than that of conventional and fuel-based technologies (coal, gas, nuclear). The differences in magnitude of land use can be shown by comparing the amount of land the U.S. devotes to each of its major energy technologies per unit of primary energy supplied by that technology. Based on an analysis of U.S. energy land allocations by Bloomberg and a U.S. primary energy supply breakdown by the U.S. Energy Information Administration (Bloomberg analysis released in 2021, EIA data for year 2019), the land required per unit energy (in million acres per quadrillion BTU) was calculated for fossil fuels, nuclear, wind, and solar:

CCCU_LUCG3
land-Intensity-relative-to-coal

Based on the analysis above, wind and solar technologies respectively require about 48x and 9x the land area required by coal to produce the same amount of primary energy. Natural gas and nuclear require 2.46x and 0.52x the amount of land that coal requires per unit of energy output. Note that this analysis only addresses the magnitude of land use and not how each technology impacts the environment; for details on how land is impacted by each technology, refer to the Life Cycle Analysis tables. For breakdowns of current U.S. energy land allocations, see [1]. It is important to note that the Bloomberg analysis [1] includes supply of all energy, including heating, transportation, and manufacturing. For breakdowns of U.S. primary energy supply by source, see [2]. The land intensity calculations assume that the Bloomberg land use data and the EIA energy supply data are representative of the U.S. energy system at the same point in time; since the reports both involve data that is around the 2019-2021 time range, we will neglect any changes in U.S. energy infrastructure within that time period.

[1]-Merrill, Dave. “The U.S. Will Need a Lot of Land for a Zero-Carbon Economy.” Bloomberg.com, Bloomberg, 29 Apr. 2021, https://www.bloomberg.com/graphics/2021-energy-land-use-economy/.
[2]-“U.S. Energy Information Administration - EIA - Independent Statistics and Analysis.” U.S. Energy Information Administration (EIA) - Data, https://www.eia.gov/totalenergy/data/browser/index.php?tbl=T01.02#/?f=A.

Staged Pressurized Oxy-Combustion

SPOC is a combustion technology with inherent carbon capture capabilities currently being developed by the CCCU. It is designed to avoid many of the issues present in traditional, post-combustion carbon capture operations, which are often a retrofitted “patch” on existing fossil fuel plants. Some of the issues SPOC avoids include: significantly less than 100% capture rates, high capture costs and energy penalties that make CCS economically uncompetitive, and the use of toxic scrubber chemicals for capture. 

Instead of removing relatively dilute CO2 from flue gas using hazardous scrubbing chemicals, SPOC technology creates a flue gas stream with a majority composition of CO2 and removes pollutants and impurities from the CO2 stream. The key features of SPOC that enable this operation are oxy-combustion and elevated operation pressure.

Oxy-combustion is the burning of fuel in high purity oxygen and recycled flue gas instead of air, resulting in flue gas composed primarily of CO2 and with reduced NOx levels (due to lack of N2). Elevated operation pressure reduces the O2 requirement for complete burnout of coal, reduces the volume of gases in the system (and thus the size and cost of system components), enables harnessing and usage of latent heat (phase change heat) of water in the flue gas, and enables easier removal of NOx and SOx from the flue gas. The high operating pressure results in an increased dew point temperature of water, enabling the moisture in the high temperature flue gas to transition from the gas to the liquid phase. The heat energy released from this phase transition can then be harnessed and used to pre-heat the water used in the steam cycle, thereby increasing the efficiency of the plant. The high pressure also enables significant percentages of the NOx and SOx in the flue gas to be absorbed by water; the Direct Contact Cooler (DCC) both cools and removes NOx and SOx the flue gas by washing it with cooling water, eliminating the need for other NOx and SOx emissions control techniques. The flue gas leaving the DCC is high purity CO2, which is then sent to the compression and purification unit (CPU) for purification to utilization (e.g. enhanced oil recovery) or sequestration grade. The integrated CO2 capture strategy of SPOC enables higher capture rates (without toxic scrubber chemicals) while incurring a much smaller energy penalty on the plant than traditional, post-combustion capture, which relies on repeated heating and cooling of a CO2 absorbent to pull relatively dilute CO2 from the flue gas, on top of the requirement for NOx, SOx, and other pollutant removal. SPOC is also capable of efficiently cofiring biomass, which enables net carbon negative operation.

SPOC’s staged combustors (multiple compact combustors connected in series-parallel) enhance efficiency by decreasing the amount of flue gas recycle required to maintain optimal heat flux from the combustors to the turbine steam. The modular design also enhances flexibility without compromising efficiency, as individual combustors can be shut down in times of low demand to allow the others to maintain full (optimal) capacity and efficiency. Flexibility is particularly important for reliably supplying variable demand without large reductions in efficiency (a.k.a increase in cost). Liquid Oxygen Storage (LOS) further enhances flexibility; the air separation unit (ASU) can increase output in times of low electricity demand and decrease output in times of high electricity demand to enable the combustors to continue operating at optimal capacity. The SPOC system is designed to efficiently handle variable demand, enabling the production of cheap, reliable energy; it also can help to mitigate supply intermittency in electricity grids with high variable renewable energy (VRE) penetration.

For more details, see: Axelbaum, Richard L. Washington University in St. Louis, St. Louis, MO, 2019, Modular Pressurized Coal Combustion for Flexible Generation, https://netl.doe.gov/sites/default/files/2020-02/Modular-Staged-Pressurized-Oxy-combustion-Power-Plant-System-Washington-University-in-St.-Louis.pdf. Accessed 9 Mar. 2022.

Indirect Supply Chain Costs

There exist certain hidden costs in energy technology supply chains that have a significant portion outside of the U.S. This is due to the stringent regulations in the U.S., mining environmental protection, occupational safety, wages, etc. Such regulations create higher supply chain costs for products sourced and manufactured in the U.S., and these higher costs are representative of the cost to prevent environmental and human damages that would otherwise exist if regulations were not in place. In various countries outside the U.S., regulations on environmental protection, worker safety, and wages are likely to be significantly less stringent than U.S. regulations. This allows for lower costs along supply chains that fall largely outside of the U.S., but it also means that those supply chains’ costs do not account for the cost of preventing the environmental and human damages that are preventable by regulations.

In the current energy economy, the U.S. sources most of its coal and natural gas domestically [1] [2], where mining and processing operations are subject to regulations that raise supply chain costs but provide a degree of environmental and human protection from the potential hazards of coal and natural gas sourcing. In contrast, most rare earth elements (REEs), polysilicon, lithium, and other battery materials used in the U.S. for wind turbines, traditional solar panels, and lithium-ion battery systems have supply chains that exist almost entirely outside of the U.S., with raw materials being sourced from various countries and processing being dominated by China [3] [4] [5] [6] [7].

REEs for permanent magnets used in direct drive wind turbines are mined in various countries, and REE processing is largely dominated by China. As explained in the Life Cycle Overview, REE processing in China has significant environmental impacts from improper waste management and indirect impacts on local populations due to pollution [3] [8] [9]; the costs of these negative impacts are not accounted for in the supply chain costs for direct drive wind turbines because measures are not being taken to prevent environmental and human damages. Polysilicon for traditional solar panels that is sourced from China has issues regarding forced labor in its supply chains [10] [11]. Due to these issues, the polysilicon supply chains do not account for the cost of workers’ rights, freedoms, protections, and proper pay. The Lithium Triangle (Argentina, Chile, and Bolivia) currently accounts for approximately 52% of world lithium reserves and 56% of world lithium resources [12]. Here, mining operations have negative impacts on the living environments of Indigenous communities, but those communities often don’t have significant power to make decisions on mining operations and often don’t receive the full economic benefits of the lithium resources extracted on their land [13]. China accounts for approximately 7% of world reserves and 6% of world resources [12]. In Tibet, where most Chinese lithium deposits are located, Indigenous populations have been forcibly relocated by the Chinese government in order to extract lithium from their lands. Tibetans largely do not receive economic benefit from the resources extracted by Chinese operations in Tibet, and do not have any say in mining decisions [14]. Cobalt is an important component in lithium-ion batteries, and the Democratic Republic of the Congo accounts for approximately 46% of world cobalt reserves (economically viable terrestrial deposits), and the vast majority of the world’s 25 million tons of terrestrial cobalt resources [12]. 20% of the DRC’s cobalt supply is mined through artisanal, small-scale mining, where workers are subjected to dangerous mining conditions, paid very little, and where a significant portion of workers are children [15]. The costs for safe working environments and fair wages are not accounted for in the supply chain of cobalt.

These environmental and human dangers that result from lightly regulated supply chains are not intrinsic to wind, solar, or battery technologies, but they are part of the current reality because these technologies have supply chains that lie outside of the U.S. and are subject to lighter regulations than supply chains for U.S. domestic coal and natural gas. However, it is important to bear in mind the inevitable cost increases that would arise from stricter environmental, safety, and wage regulations that would ensure ethical supply chains for wind, solar, and battery technologies. These higher supply chain costs effectively account for environmental and human protection costs and are eventually borne by end consumers.

[1]-Almost All U.S. Coal Production Is Consumed for Electric Power, EIA, 18 June 2020, https://www.eia.gov/todayinenergy/detail.php?id=44155.
[2]-In 2018, 90% of the Natural Gas Used in the United States Was Produced Domestically, EIA, 9 July 2019, https://www.eia.gov/todayinenergy/detail.php?id=40052.
[3]-Huang, Xiang, et al. “Protecting the Environment and Public Health from Rare Earth Mining.” AGU Publications, Wiley, 1 Nov. 2016, https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016EF000424.
[4]-
“Does China Pose a Threat to Global Rare Earth Supply Chains?” ChinaPower Project, Center for Strategic and International Studies, 12 May 2021, https://chinapower.csis.org/china-rare-earths/.
[5]-“Helena Kennedy Centre.” In Broad Daylight Uyghur Forced Labour in the Solar Supply Chain, Sheffield Hallam University, https://www.shu.ac.uk/helena-kennedy-centre-international-justice/research-and-projects/all-projects/in-broad-daylight.
[6]-“China Controls Sway of Electric Vehicle Power through Battery Chemicals, Cathode and Anode Production.” Benchmark Mineral Intelligence, 6 May 2020, https://www.benchmarkminerals.com/membership/china-controls-sway-of-electric-vehicle-power-through-battery-chemicals-cathode-and-anode-production/.
[7]-Els, Frik. “Chart: China's Stranglehold on Electric Car Battery Supply Chain.” MINING.COM, Mining.com, 23 Apr. 2020, https://www.mining.com/chart-chinas-stranglehold-on-electric-car-battery-supply-chain/.
[8]-“Rare Earths: Shades of Grey.” China Water Risk, China Water Risk, June 2016, https://www.chinawaterrisk.org/wp-content/uploads/2016/07/CWR-Rare-Earths-Shades-Of-Grey-2016-ENG.pdf.
[9]-Su, Alice. “The Hidden Costs of China's Rare-Earth Trade.” Los Angeles Times, Los Angeles Times, 29 July 2019, https://www.latimes.com/world-nation/story/2019-07-28/china-rare-earth-tech-pollution-supply-chain-trade.
[10]-Duffy, Clare. “Blistering Report Alleges Chinese Solar Panel Supply Chain Tainted by Forced Labor.” CNN, Cable News Network, 14 May 2021, https://www.cnn.com/2021/05/14/energy/china-solar-panels-uyghur-forced-labor-dst-intl-hnk/index.html.
[11]-“Mineral Commodity Summaries 2022.” USGS Publications Warehouse, USGS, 31 Jan. 2022, https://pubs.usgs.gov/periodicals/mcs2022/mcs2022.pdf.
[12]-Neiser, Abby. “The Double-Edged Sword of Lithium Mining's Sustainability in South America.” Panoramas, University of Pittsburg, 8 Feb. 2021, https://www.panoramas.pitt.edu/economy-and-development/double-edged-sword-lithium-mining%E2%80%99s-sustainability-south-america.
[13]-“Lithium in Tibet - Tibet's Geography.” Free Tibet, https://freetibet.org/freedom-for-tibet/land-and-environment/lithium-in-tibet/.
[14]-“Democratic Republic of Congo: ‘This Is What We Die for’: Human Rights Abuses in the Democratic Republic of the Congo Power the Global Trade in Cobalt.” Amnesty International, Amnesty International, 1 June 2021, https://www.amnesty.org/en/documents/afr62/3183/2016/en/.