Natural Gas Electricity Generation Research Articles

Life cycle assessment of a virtual power plant: Evaluating the environmental performance of a system utilising solar photovoltaic generation and batteries

As the world shifts to renewable energy sources to mitigate climate change, virtual power plants (VPPs) have emerged as an innovative solution for integrating distributed renewable generation. This study conducted a comprehensive Life Cycle Assessment (LCA) for a 40 MW VPP in operation in Aotearoa New Zealand, comprising residential solar photovoltaic systems with battery storage. Unlike traditional LCA studies that focus on individual components, this study evaluates the full life cycle impacts of a VPP, offering a holistic view of its environmental implications. Additionally, the study considered electricity fed back to the grid, which avoids grid electricity, or electricity generation from natural gas. The findings reveal an estimated life cycle greenhouse gas (GHG) emissions of 45.3–78.9 gCO2eq/kWh for the VPP, depending on what the surplus electricity replaces. Notably, avoiding natural gas electricity generation by returning surplus electricity to the grid yields a significant credit of −47.3 gCO2eq/kWh. The life cycle GHG emissions of the VPP are highly sensitive to PV generation. If the systems are operated at their maximum potential, the overall emissions reduce by 17.6%. Conversely, when operated at minimum potential, the emissions increase by 23.2%. Additionally, uncertainties in the energy demand to manufacture the battery cells can alter GHG emissions from a 6.7% reduction to a 14.3% increase. This study underscores the complexity of evaluating environmental performances of VPPs and fills a gap in the literature by presenting the potential environmental impacts and benefits of VPPs, shedding light on their role in fostering sustainability with the energy transition.

Modeling and design optimization of carbon-free hybrid energy systems with thermal and hydrogen storage

With increasing demand for carbon-free power to mitigate climate change, hybrid energy systems (HES) is expected to play an instrumental role in the coming decades. The study is focused on replacing all coal and natural gas electricity generation in the state of Texas with solar, wind, and nuclear power. As an integral part of the designed nuclear-renewable hybrid energy system (N-RHES), both thermal and hydrogen storages are used to provide daily short-term and seasonal energy storage. Each subsystem is dynamically modeled in Dymola/Modelica with hourly wind speed and solar irradiance data entering the wind turbine and solar PV modules. Using Year 2020 data, the N-RHES is collectively controlled to meet hourly energy demand of the state. Aiming to minimize the system's levelized cost of energy (LCOE) while meeting the demand at all times of the year, an optimization algorithm is developed to find an optimum design point of the system. The optimized LCOE of the system was found to be $73.04/MWh, which results from 61 Natrium nuclear power plants, 5317 3.2-MW wind turbines, and 307.9 km2 of solar PV panels. While this optimized LCOE is greater than the current LCOE, it provides carbon-free electricity for the entire state of Texas. According to the design, most of the demand is met by nuclear power with the rest being a near even split between wind and solar power. Although the stored hydrogen in salt caverns contributed only to a small portion of the total electricity production, it provides a large amount of green hydrogen to future clean energy markets.

Comparing Greenhouse Gas Impacts from Domestic Coal and Imported Natural Gas Electricity Generation in China

In 2019, coal power accounted for 65% of China’s electricity and coal accounted for 71% of its 10.2 GTpa CO2 emissions. To meet its pledge of peak carbon by 2030 and carbon neutrality by 2060, China plans to shift away from coal. Fuel switching to natural gas for electrical generation is an interim solution that is in the portfolio of measures for meeting these goals. However, because of variability in emissions from coal and natural gas supply chains, the potential for benefiting from fuel switching also varies. Here, we use a high-resolution basin-to-power plant analysis for estimating methane and CO2 emissions in natural gas and coal supply chains. We illustrate how the variations in supply chains at the level of the sourcing of natural gas and coal from individual production regions can lead to differences in the effectiveness of fuel switching in reducing greenhouse gas emissions. The analyses are applied to four switching scenarios from domestic coal to imported natural gas at representative power plants in China. Life cycle emission factors for the natural gas supply chains evaluated in this study range from 650 to 1000 kg carbon dioxide/MWh of electricity generated and from 2.3 to 13 kg methane/MWh, depending on the allocation choice, power generation technology, and production region. For the coal supply chain, emissions range from 850 to 1100 kg carbon dioxide/MWh and from 0.4 to 4.0 kg methane/MWh, depending on the power generation technology and production region. We show that for these scenarios, in the short term fuel switching can increase radiative forcing by a factor of 3 or decrease it by 70%, depending on the supply chains, generation technology, and, in the case of natural gas, co-product allocation choices in the supply chain. We also quantify consumptive losses of natural gas over long supply chains and show that fuel switching results in differences in radiative forcing that evolve over time due to the influence of methane emissions.

Environmental performance of high-efficiency natural gas combined cycle plant

ABSTRACT The aim of this paper is to assess the environmental impact of electricity production from one of the best available gas-fired power plants and to compare it with the current mix of electricity and the supply of electricity from a typical gas plant. The scope of the paper includes gas field exploration, natural gas processing, pipeline transportation, and electricity generation as well as construction and decommissioning of the plant. The influence of efficiency of the plant and natural gas supply from different countries on the results is explored within the sensitivity analysis. The findings indicate that the global warming potential is estimated at 388 g CO2 eq./kWh. The natural gas system described offers major improvements in all considered environmental impacts compared to the typical natural gas electricity generation system, ranging from 4.9% for abiotic depletion potential to 82.1% for acidification potential. Increasing the contribution of natural gas in the electricity mix would reduce only eutrophication, human toxicity, freshwater, and marine aqua ecotoxicity potentials. The lower environmental impacts in this paper are due to the different gas composition, relatively high efficiency assumed as well as the proximity of Turkey to Azerbaijan which reduces transport distances. The results of this study would be of benefit to the future energy market, as natural gas is one of the electricity-producing plants promoted in Turkey.

A bridge too far? The role of natural gas electricity generation in US climate policy

Natural gas has been promoted as a ‘‘bridge’’ fuel toward a low-carbon future by offering near-term emissions reductions at lower cost. Existing literature is inconclusive on the short-term emissions benefits of more abundant natural gas. The long-lived nature of natural gas infrastructure also threatens to lock in emissions levels well above longer-term targets. If natural gas can offer short-to-medium term benefits, how much of a bridge should we build? Using ARTIMAS, a foresighted computable general equilibrium model of the US economy, we interact scenarios developed by the EMF-34 study group related to abundant natural gas, low-cost renewables, and a carbon tax to examine the role of natural gas in a carbon-constrained future. We find that abundant natural gas alone does not have a significant impact on CO2 emissions. We also find that, under a higher carbon tax, natural gas investment of approximately $10 billion per year declines to zero at a tax of about $40/ton and existing natural gas assets face significant risk of impairment. Last, the presence of abundant natural gas lowers the marginal welfare cost of abating small amounts of CO2 but is likely to raise the cost of abatement levels consistent with common climate objectives. The integrated welfare costs of climate policy depend on how much abatement we must undertake.

Coupling Carbon Capture from a Power Plant with Semi-automated Open Raceway Ponds for Microalgae Cultivation.

In the United States, 35% of the total carbon dioxide (CO2) emissions come from the electrical power industry, of which 30% represent natural gas electricity generation. Microalgae can biofix CO2 10 to 15 times faster than plants and convert algal biomass to products of interest, such as biofuels. Thus, this study presents a protocol that demonstrates the potential synergies of microalgae cultivation with a natural gas power plant situated in the southwestern United States in a hot semi-arid climate. State-of-the-art technologies are used to enhance carbon capture and utilization via the green algal species Chlorella sorokiniana, which can be further processed into biofuel. We describe a protocol involving a semi-automated open raceway pond and discuss the results of its performance when it was tested at the Tucson Electric Power plant, in Tucson, Arizona. Flue gas was used as the main carbon source to control pH, and Chlorella sorokiniana was cultivated. An optimized medium was used to grow the algae. The amount of CO2 added to the system as a function of time was closely monitored. Additionally, other physicochemical factors affecting algal growth rate, biomass productivity, and carbon fixation were monitored, including optical density, dissolved oxygen (DO), electroconductivity (EC), and air and pond temperatures. The results indicate that a microalgae yield of up to 0.385 g/L ash-free dry weight is attainable, with a lipid content of 24%. Leveraging synergistic opportunities between CO2 emitters and algal farmers can provide the resources required to increase carbon capture while supporting the sustainable production of algal biofuels and bioproducts.

Sustainability assessment of gas based power generation using a life cycle assessment approach

PurposeIndia is a developing economy along with an increasing population estimated to be the largest populated country in about seven years. Simultaneously, its power consumption is projected to increase more than double by 2020. Currently, the dependence on coal is relatively high, making it the largest global greenhouse gas emitting sector which is a matter of great concern. The purpose of this paper is to evaluate the environmental impacts of the natural gas electricity generation in India and propose a model using a life cycle assessment (LCA) approach.Design/methodology/approachLCA is used as a tool to evaluate the environmental impact of the natural gas combined cycle (NGCC) power plant, as it adopts a holistic approach towards the whole process. The LCA methodology used in this study follows the ISO 14040 and 14044 standards (ISO 14040: 2009; ISO 14044: 2009). A questionnaire was designed for data collection and validated by expert review primary data for the annual environmental emission was collected by personally visiting the power plant. The study follows a cradle to gate assessment using the CML (2001) methodology.FindingsThe analysis reveals that the main impacts were during the process of combustion. The Global warming potential is approximately 0.50 kg CO2 equivalents per kWh of electricity generation from this gas-based power plant. These results can be used by stakeholders, experts and members who are authorised to probe positive initiative for the reduction of environmental impacts from the power generation sector.Practical implicationsConsidering the pace of growth of economic development of India, it is the need of the hour to emphasise on the patterns of sustainable energy generation which is an important subject to be addressed considering India’s ratification to the Paris Climate Change Agreement. This paper analyzes the environmental impacts of gas-based electricity generation.Originality/valuePresenting this case study is an opportunity to get a glimpse of the challenges associated with gas-based electricity generation in India. It gives a direction and helps us to better understand the right spot which require efforts for the improvement of sustainable energy generation processes, by taking appropriate measures for emission reduction. This paper also proposes a model for gas-based electricity generation in India. It has been developed following an LCA approach. As far as we aware, this is the first study which proposes an LCA model for gas-based electricity generation in India. The model is developed in line with the LCA methodology and focusses on the impact categories specific for gas-based electricity generation.

Managerial flexibility in levelized cost measures: A framework for incorporating uncertainty in energy investment decisions

Many irreversible long-run capital investments entail opportunities for managers to respond flexibly to changes in the economic environment. However, common levelized cost measures used to guide decision-making, such as the levelized cost of electricity, implicitly assume that the values of random economic variables are known with certainty when investment decisions are made. This assumption implies, often incorrectly, that managerial flexibility carries zero value. This paper improves levelized cost measures by deriving an expansion that accounts for both uncertainties in relevant variables and the value of managerial flexibility in responding to them. This method is applied to quantify the value of flexibility in two example decision problems. In one, an operator of a natural gas electricity generation facility evaluates whether to invest in carbon capture capabilities. Another considers retirement decisions for U.S. nuclear plants. These examples illustrate that simplified cost metrics can inaccurately guide decision-making by inflating cost estimates relative to the proposed levelized cost measure that accounts for uncertainty and flexibility.

Gas-fired power in the UK: Bridging supply gaps and implications of domestic shale gas exploitation for UK climate change targets

There is a projected shortcoming in the fourth carbon budget of 7.5%. This shortfall may be increased if the UK pursues a domestic shale gas industry to offset projected decreases in traditional gas supply. Here we estimate that, if the project domestic gas supply gap for power generation were to be met by UK shale gas with low fugitive emissions (0.08%), an additional 20.4MtCO2e11Megatonne carbon dioxide equivalent (MtCO2e). would need to be accommodated during carbon budget periods 3–6. We find that a modest fugitive emissions rate (1%) for UK shale gas would increase global emissions compared to importing an equal quantity of Qatari liquefied natural gas. Additionally, we estimate that natural gas electricity generation would emit 420–466MtCO2e (460 central estimate) during the same time period within the traded EU emissions cap. We conclude that domestic shale gas production with even a modest 1% fugitive emissions rate would risk exceedance of UK carbon budgets. We also highlight that, under the current production-based greenhouse gas accounting system, the UK is incentivized to import natural gas rather than produce it domestically.

An assessment of price convergence between natural gas and solar photovoltaic in the U.S. electricity market

The U.S. shale boom has exerted downward pressure on natural gas prices nationally, widened oil‐to‐gas price spreads, and accelerated coal‐to‐gas fuel substitution. One concern is the impact of the rising production of shale gas on further development of a domestic solar photovoltaic (PV) market. Specifically, will lower natural gas prices slow or even reverse the current rapid growth in the solar market? Using the Phillips–Sul convergence test, this paper investigates whether the levelized cost of energy (LCOE) of solar PV and natural gas electricity generation in the United States have converged. Using weekly Henry Hub‐linked natural gas spot prices and utility PV system prices from 2010 to 2015, empirical tests for convergence are applied to examine the extent of spot market integration and the speed with which market forces move the two energy prices toward equilibrium. The paper also assesses the link between the MAC Solar Energy Index (SUNIDX) and the S&P GSCI natural gas index spot prices for evidence of market integration during 2007–2015. We conclude that PV and natural gas prices are not converging, and the two markets are not integrated nationally, but some level of integration could exist at regional and state levels that will need to be tested in future research. We also conclude that complementary use of the technologies is likely; while price convergence is not likely to occur soon, distinctive complementary benefits of each resource compared to each other (e.g., fast‐start capabilities for gas and low price volatility for PV) will offer opportunities that expand market demand for both. WIREs Energy Environ 2017, 6:e238. doi: 10.1002/wene.238This article is categorized under: Photovoltaics > Economics and Policy Energy Systems Economics > Systems and Infrastructure

Life cycle greenhouse gas emissions from U.S. liquefied natural gas exports: implications for end uses.

This study analyzes how incremental U.S. liquefied natural gas (LNG) exports affect global greenhouse gas (GHG) emissions. We find that exported U.S. LNG has mean precombustion emissions of 37 g CO2-equiv/MJ when regasified in Europe and Asia. Shipping emissions of LNG exported from U.S. ports to Asian and European markets account for only 3.5-5.5% of precombustion life cycle emissions, hence shipping distance is not a major driver of GHGs. A scenario-based analysis addressing how potential end uses (electricity and industrial heating) and displacement of existing fuels (coal and Russian natural gas) affect GHG emissions shows the mean emissions for electricity generation using U.S. exported LNG were 655 g CO2-equiv/kWh (with a 90% confidence interval of 562-770), an 11% increase over U.S. natural gas electricity generation. Mean emissions from industrial heating were 104 g CO2-equiv/MJ (90% CI: 87-123). By displacing coal, LNG saves 550 g CO2-equiv per kWh of electricity and 20 g per MJ of heat. LNG saves GHGs under upstream fugitive emissions rates up to 9% and 5% for electricity and heating, respectively. GHG reductions were found if Russian pipeline natural gas was displaced for electricity and heating use regardless of GWP, as long as U.S. fugitive emission rates remain below the estimated 5-7% rate of Russian gas. However, from a country specific carbon accounting perspective, there is an imbalance in accrued social costs and benefits. Assuming a mean social cost of carbon of $49/metric ton, mean global savings from U.S. LNG displacement of coal for electricity generation are $1.50 per thousand cubic feet (Mcf) of gaseous natural gas exported as LNG ($.028/kWh). Conversely, the U.S. carbon cost of exporting the LNG is $1.80/Mcf ($.013/kWh), or $0.50-$5.50/Mcf across the range of potential discount rates. This spatial shift in embodied carbon emissions is important to consider in national interest estimates for LNG exports.