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. 


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. 


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. 


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. 


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. 


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:


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, 29 Apr. 2021,
[2]-“U.S. Energy Information Administration - EIA - Independent Statistics and Analysis.” U.S. Energy Information Administration (EIA) - Data,

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, Accessed 9 Mar. 2022.