Grid Emission Factor Research Articles

Data used in "Comparing empirical and model-based approaches for calculating dynamic grid emission factors: an application to CO2-minimizing storage dispatch in Germany"

Data used in "Comparing empirical and model-based approaches for calculating dynamic grid emission factors: an application to CO2-minimizing storage dispatch in Germany"

Design of low-carbon utility systems: Exploiting time-dependent grid emissions for climate-friendly demand-side management

Efficient energy supply is key to reduce industrial greenhouse gas emissions. In the industry, energy is often supplied by on-site utility systems with electricity grid connection. Usually, electricity from the grid is assumed to have annually averaged emission factors when greenhouse gas emissions are calculated. However, emissions from electricity production are in fact time-dependent to match continuously varying demand and supply. These time dependent emissions offer the potential to reduce emissions by temporal shifting of electricity demand in demand-side management.Here, we investigate the impact of time-dependent grid mix emissions for low-carbon utility systems. For this purpose, we present a detailed mixed-integer linear programming model for a low-carbon utility system. Subsequently, we compute time-dependent grid emission factors based on the current mix and based on the marginal technologies. These grid emission factors serve as input to determine and economic and environmental trade-off curves. We show that emissions can be reduced by up to 6% at the same costs by considering time-dependent grid mix emissions, instead of annual average grid emissions. Marginal time-dependent emission factors even allow to reduce emissions by up to 60%. Our work shows that time-dependent grid emissions factors could enable climate-friendly demand-side management leading to significant emission reductions.

Carbon emissions pinch analysis (CEPA) for energy sector planning in Nigeria

Nigeria has abundant of fossils and renewable energy resources. However, systematic energy planning techniques are desirable to facilitate the sustainable management of these resources. In this work, carbon emission pinch analysis which incorporates macro-level sectorial electricity planning was applied for Nigeria. The minimum renewable targets were determined, and some of the possibilities of realising meaningful emissions reduction with increases in demand were revealed. The minimum renewable target of 408 TW h is required to keep emissions level as that of year 2015, while at the same time meeting the projected demand of 530 TW h in 2035. The present estimation shows that renewable energy applications could immensely contribute to the energy mix and favourable over fossil fuel for carbon emissions reductions. Biomass has the potential to sustain the nation from energy shortages, decrease the grid emission factor for Nigeria electricity sector from 0.91 t CO2/TW h (2015) to 0.21 t CO2/TW h (2035). The electricity generation mix for year 2035 is best derived from biomass, solar, and hydropower.

Comparison of Greenhouse Gas Reduction Potential through Renewable Energy Transition in South Korea and Germany

Germany and South Korea are the world’s sixth and seventh largest emitters of greenhouse gases, respectively; their main sources of pollution being fossil-fueled power plants. Since both countries signed the Paris Agreement in 2016, renewable energy transition is emerging as an effective means and method for avoiding air pollutant emissions and for replacing old fossil-fueled power plants. This paper attempts to evaluate—by using a grid emission factor dependent on a series of energy mix scenarios—the potential for South Korea and Germany to reduce their air pollutants (CO2, NOx, SOx, PM (particulate matter)) until 2030. South Korea plans to reduce greenhouse gas emissions by increasing nuclear power, while Germany aims to do so by shutting down its nuclear power plants and expanding the proportion of renewable energy in the energy mix to over 50%. Therefore, both countries are able to achieve their voluntary greenhouse gas reduction targets in the power sector. However, since the uncertainty of the CO2 emission factor of coal power plants in South Korea is as high as 10%, efforts to reduce that uncertainty are required in order to produce a reliable assessment of the avoided emissions.

Tracking decarbonisation in the mining sector

Greenhouse gas (GHG) emissions increase as mining companies transport ore over increased distances in opencast operations or extract ore from deeper levels in underground operations. The rising costs of energy sources and enhanced awareness of the impacts of GHG emissions support energy- and emission-reduction initiatives. This paper evaluates the metrics used in GHG emissions projections and target-setting over a ten-year period from 2005, linked to the South African Energy Efficiency Accord. The GHG inventories of a gold- and iron ore-mining company, together with the implemented energy saving projects, were analysed to evaluate progress against targets. A broad target value, defined as a percentage reduction of GHG emissions over time, was found to be problematic in monitoring performance over time. A direct link between emissions and output metrics was not found, due to external factors, such as the impact of changes in the grid emission factor, acquisitions and divestments, and internal factors, including changes in ore grade or mining depth. Using a metric linked to the activity within the operations, such as total tonnes mined, is, therefore, more appropriate for mining companies than production output. A methodological tool, using both the inventory and the savings from implemented mitigation initiatives, is proposed to improve GHG emissions projections, establishing a counterfactual baseline, and to support target setting. Decarbonisation of the mining industry would require careful review of the metrics to project and set GHG reduction targets.

Trade implications of grid emission factors under climate change and the green economy: Comparative study of African and Asian continents

Trade, climate change, and the green economy are aspects that converge on the carbon footprint of organisations, products and countries. The carbon footprint is in turn linked directly to the grid emission factors (GEFs) of a country or sub-regions within that country. In an epoch where global citizens are increasingly aware of the adverse impacts of high greenhouse gas emissions leading to global warming, low carbon footprints are likely to attract greater trade opportunities. African and Asian countries have embraced the green economy to address economic development, environmental management and social equity challenges. The advent of the green economy means that trade is likely to result in the more efficient allocation of natural resources, as well as improved access to green goods, services and technologies. Through the examination and analysis of publicly available and accessible data and documents, this article seeks to compare the ‘green’ trade competitiveness of Asian and African economies as measured through carbon footprints. The results of the study show that Africa is relatively cleaner than Asia. Therefore, ceteris paribus, if GEFs are used to determine trading partners, Africa stands a better chance. The research findings can be used to make informed strategic trade decision in favour of environmental sustainability.

Rethinking investment planning and optimizing net zero emission buildings

Increased awareness of climate change has precipitated more stringent mitigation targets. Public sector institutions in Canada are committed to becoming carbon neutral to attain a leadership position in climate change mitigation-related initiatives. Recent statistics reveal that buildings account for the majority of the corporate carbon footprint of public sector institutions. Hence, there is an increasing interest towards developing net zero energy and net zero emission buildings to comply with climate action targets. With limited financial resources, public sector institutions must optimize investments into building energy retrofits by considering lifecycle cost (LCC), overall energy performance, and related greenhouse gas (GHG) emission. The aim of this paper is to develop an investment planning approach for net zero emission buildings (NZEB). First, an investment planning approach for NZEB is proposed. A typical recreational centre building in British Columbia, Canada, was used as the archetype to demonstrate the concept. Second, innovative and proven building energy retrofits were analysed using energy simulation software to assess the impact on energy consumption reduction, GHG emissions, and LCC. Third, impacts of geographical location, tariff regimes, and grid emission factors on energy retrofits were studied by locating the same building in other provinces of Canada. This study revealed that net zero energy investment has a strong correlation to the grid emission factor. The proposed approach in this paper will assist building managers and owners in retrofitting and budget planning.

Integrated Model for Energy and CO2 Emissions Analysis from Thailand's Long-term Low Carbon Energy Efficiency and Renewable Energy Plan

This paper builds the energy demand and supply model from the bottom-up LEAP software and focus on evaluating and providing insights to the long-term energy and greenhouse gas impact from national energy efficiency and alternative energy plan focus from 2015 to 2036 under the 2010 base year. From the results, the energy demand would increase from 84.77 Mtoe in 2015 to 172.29 Mtoe, or 103.24% in 2036. The greenhouse gas emission would decrease from 503.34 MtCO2 in 2036 by 161 and 116 Mt-CO2 from energy efficiency and alternative energy development plan in 2036, respectively. We also found that this mitigation also impacts to the decrease of grid emission factor from 506 in the BAU to 339 and 140 kgCO2-eq per MWh, respectively due to higher renewable energy sources and imported hydro energy. Policy recommendations to deploy both plans are also raised.

Influence of PV technology and system design on the emission balance of a net zero emission building concept

This paper presents an analysis of how the design of a photovoltaic (PV) system influences the greenhouse gas emission balance in a net zero emission building (nZEB). In a zero emission building, the emissions associated both with the energy required in the operation of the building (operational emissions) and the energy used to produce the building materials (embodied emissions) are offset by renewable energy generated on-site (avoided emissions). The analysis is applied to a nZEB concept for a single-family building, developed by the Norwegian Research Centre on Zero Emission Buildings. Previous analyses have shown that the installation of a PV system accounts for a significant share of the embodied emissions of a nZEB. The objective of this paper is to assess how the PV system design choices influence the embodied and avoided emissions, in order to determine how the environmental impact can be minimised. Four different PV technologies (Si-mono, poly-Si and CIS, and high-efficiency Si-mono) in four different system designs for flat roofs are evaluated using two different grid emission factors. The installations are compared by means of net avoided emissions, greenhouse gas payback time (GPBT), greenhouse gas return on investment (GROI), and finally the net emission balance of the building. The results show that the system with the largest area of high-efficiency Si-mono modules achieves the best lifetime emission balance, but that the greenhouse gas return on investment is highest for the optimally oriented CIS modules.

An Integrated Assessment by Models for Energy Systems Analysis and Life-Cycle Assessment with a Case Study of Advanced Fossil-Fired Power Plants in China

We developed an integrated assessment (IA) using models for energy systems analysis and life-cycle assessment (LCA). Based on this assessment framework, we developed cost-benefit analysis (CBA) case studies for a hypothetical project designed to introduce advanced fossil-fired power generation technologies in China. Our MARKAL model for Japan confirmed that radical reductions (i.e., 80 % by 2050) of carbon dioxide (CO2) could be attained from energy systems alone and that credit for emission allowances was required. We evaluated life-cycle costs and emissions of carbon dioxide, sulfur oxide, and nitrogen oxide gases for the energy technologies using an LCA model. Further, we applied a power generation planning model for six Chinese grids to provide a power mix structure, potentially producing credit by installing fossil-fired power generation technology and by using baseline grid emission factors with an average cost of electricity. Finally, by using dynamic emission reductions and additional costs from the two models, we conducted case studies of CBA for a hypothetical project to install the technologies in China. This was accomplished by evaluating emission reductions in monetary terms and by applying a life-cycle impact assessment model. A unique feature of our IA is its dynamic (time-varying) assessment of costs and benefits.

Regional Variability and Uncertainty of Electric Vehicle Life Cycle CO₂ Emissions across the United States.

We characterize regionally specific life cycle CO2 emissions per mile traveled for plug-in hybrid electric vehicles (PHEVs) and battery electric vehicles (BEVs) across the United States under alternative assumptions for regional electricity emission factors, regional boundaries, and charging schemes. We find that estimates based on marginal vs average grid emission factors differ by as much as 50% (using National Electricity Reliability Commission (NERC) regional boundaries). Use of state boundaries versus NERC region boundaries results in estimates that differ by as much as 120% for the same location (using average emission factors). We argue that consumption-based marginal emission factors are conceptually appropriate for evaluating the emissions implications of policies that increase electric vehicle sales or use in a region. We also examine generation-based marginal emission factors to assess robustness. Using these two estimates of NERC region marginal emission factors, we find the following: (1) delayed charging (i.e., starting at midnight) leads to higher emissions in most cases due largely to increased coal in the marginal generation mix at night; (2) the Chevrolet Volt has higher expected life cycle emissions than the Toyota Prius hybrid electric vehicle (the most efficient U.S. gasoline vehicle) across the U.S. in nearly all scenarios; (3) the Nissan Leaf BEV has lower life cycle emissions than the Prius in the western U.S. and in Texas, but the Prius has lower emissions in the northern Midwest regardless of assumed charging scheme and marginal emissions estimation method; (4) in other regions the lowest emitting vehicle depends on charge timing and emission factor estimation assumptions.

Increasing Precision in Greenhouse Gas Accounting Using Real‐Time Emission Factors

SummaryFor many companies, the greenhouse gas (GHG) emissions associated with their purchased and consumed electricity form one of the largest contributions to the GHG emissions that result from their activities. Currently, hourly variations in electricity grid emissions are not considered by standard GHG accounting protocols, which apply a national grid emission factor (EF), potentially resulting in erred estimates for the GHG emissions. In this study, a method is developed that calculates GHG emissions based on real‐time data, and it is shown that the use of hourly electricity grid EFs can significantly improve the accuracy of the GHG emissions that are attributed to the purchased and consumed electricity of a company. A model analysis for the electricity delivered to the Spanish grid in 2012 reveals that, for companies operating during the day, GHG emissions calculated by the real‐time method are estimated to be up to 5% higher (and in some special cases up to 9% higher) than the emissions calculated by the conventional method in which a national grid EF is applied, whereas for companies operating during nightly hours, GHG emissions are estimated to be as low as 3% below the GHG emissions determined by the conventional method. A significant error can therefore occur in the organizational carbon footprint (CF) of a company and, consequently, also in the product CF. It is recommended that hourly EFs be developed for other countries and power grids.

Economic Analysis of Cikaso Mini Hydro Power Plant as a CDM Project for Increasing IRR

Renewable energy fueled power generations are few developed by private sector in Indonesia. High-cost investment and low electricity selling price to PT PLN as a single buyer is main barriers for private sector to involve in the development of renewable energy fueled power generations. In this project, the economic feasibility of Mini Hydro Power Plant of Cikaso with capacity of 5.3 MW, located at Sukabumi Regency, West Java province was assessed. This project utilized revenue generated from carbon market to increase the economic feasibility. Procedure to register the project to United Nation for Climate Change Convention (UNFCCC) as a Clean Development Mechanism project was explained in detail. Approved Consolidation Methodology (ACM) 0002 Version 12.3.0 was used to calculate grid emission factor in Jawa-Bali-Madura the grid electricity system. It was calculated that the grid emission factor is 0.833 (t-CO2/MWh), and the carbon emission reduction generated for this project is 21,982 ton/year. From the analysis result, it can be proven that the additional revenue from carbon credit could increase the project IRR from 10.28% to 13.52%.

Evaluation of Energy Consumption and Greenhouse Gas Emissions in Preparation of Cellulose Nanofibers from Woody Biomass

<abstract><title><italic>Abstract. </italic></title> The purpose of this study is to assess the energy consumption and greenhouse gas (GHG) emissions of a mechanochemical method for preparing cellulose nanofibers (CNF) from woody biomass using a life cycle assessment (LCA) approach. The energy requirements and GHG emissions from CNF production were compared to those of petroleum-based polymers to evaluate the environmental performance of CNF as a reinforcement of polypropylene (PP) or other petroleum-based polymers. The functional unit used in this study was 1 kg dry CNF. The background data (emission factors of industrial steam and water, wood density, grid emission factor, etc.) were collected from the Inventory Database for Environmental Analysis (IDEA) and published literature. The foreground data (power, heat, and water requirements in a CNF production plant) were obtained from pilot plant experiments. The energy requirement for preparing CNF was 11.1 to 30.2 MJ kg^-1, which was lower than that of petroleum-based polymers (63.4 to 131.0 MJ kg^-1). The GHG emissions of preparing CNF ranged from 1.2 to 3.7 kg CO₂eq kg^-1, without accounting for carbon fixation of the biomass. The water consumption for producing CNF was 17.8 to 19.4 L kg^-1, which was much lower than that of petroleum-based polymers (192.6 to 960.8 L kg^-1). When the CNF were used to produce a composite with PP, the maximum GHG reduction was 2.4 kg CO₂eq kg^-1, taking into account carbon fixation of the biomass. The results showed that the utilization of CNF prepared from woody biomass using the mechanochemical method could contribute to saving energy and mitigating GHG emissions.

Quantifying Baseline Emission Factors of Air Pollutants in China’s Regional Power Grids

Drawing lessons from the clean development mechanism (CDM), this paper developed a combined margin methodology to quantify baseline emission factors of air pollutants in China's regional power grids. The simple average of baseline emission factors of SO2, NOX, and PM2.5 in China's six power grids in 2010 were respectively 1.91 kg/MWh, 1.83 kg/MWh and 0.32 kg/MWh. Several low-efficient mitigation technologies, such as low nitrogen oxide burner (LNB), were suggested to be replaced or used together with other technologies in order to virtually decrease the grid's emission factor. The synergies between GHG and air pollution mitigation in China's power sector was also notable. It is estimated that in 2010, that every 1% CO2 reduction in China's power generation sector resulted in the respective coreduction of 1.1%, 0.5%, and 0.8% of SO2, NOX, and PM2.5. Wind is the best technology to achieve the largest amount of coabatement in most parts of China. This methodology is recommended to be used in making comprehensive air pollution control strategies and in cobenefits analysis in future CDM approval processes.

A comparison of power generation and ethanol production using sugarcane bagasse from the perspective of mitigating GHG emissions

The mitigation of greenhouse gas (GHG) emissions from power generation and two ethanol production options from sugarcane bagasse were compared at grid emission factors ranging from 0.0 to 1.0kg of carbon dioxide (CO2) equivalent per kWh. The first ethanol production method (EP 1) directly purchased electricity and steam from the grid and the factory, and the second ethanol production method (EP 2) derived the required electricity and steam from the cogeneration system using the sugarcane bagasse as boiler fuel. Data pertaining to GHG emissions from power generation were collected from published studies. A process for ethanol production from sugarcane bagasse was designed, and a simulator was developed to generate the process data using Microsoft Excel. Results show that power generation is the preferential option when the grid emission factors are higher than 0.45kgCO2eq/kWh. The EP 1 was advantageous in mitigating the GHG emissions when the grid emission factors were lower than 0.19kgCO2eq/kWh, and the EP 2 might be the most environmentally beneficial when the grid emission factors were between 0.19 and 0.45kgCO2eq/kWh. It is hoped that these results could be helpful in determining how to best utilize sugarcane bagasse.

What is the carbon emission factor for the South African electricity grid?

One of the most important parameters for developing Clean Development Mechanism (CDM) project proposals in the electricity sector (both supply and efficiency) is the standard electricity ‘grid emission factor’, which represents the carbon dioxide related to a megawatt hour of electricity supplied or saved on the grid. While there are detailed guidelines from the CDM Executive Board on how to calculate this emission factor, the values used in registered CDM projects in South Africa vary widely, both due to changes in the rules over time and also to misapplication of the rules. This paper shows how the application of the latest guidelines gives a ‘combined margin emission factor’ for South Africa of 0.957 tCO2/MWh in 2009/2010. The variation in emission factors in the literature, as well as the importance of reducing the transaction costs for South African project developers, points to the need for an official published grid emission factor from the CDM host country authority in South Africa, the Designated National Authority (DNA), within the Department of Energy.

Real-World Energy Use and Emission Rates for Idling Long-Haul Trucks and Selected Idle Reduction Technologies

Long-haul freight trucks typically idle for 2000 or more hours per year, motivating interest in reducing idle fuel use and emissions using auxiliary power units (APUs) and shore-power (SP). Fuel-use rates are estimated based on electronic control unit (ECU) data for truck engines and measurements for APU engines. Engine emission factors were measured using a portable emission measurement system. Indirect emissions from SP were based on average utility grid emission factors. Base engine fuel use and APU and SP electrical load were analyzed for 20 trucks monitored for more than 1 yr during 2.76 million mi of activity within 42 U.S. states. The average base engine fuel use varied from 0.46 to 0.65 gal/hr. The average APU fuel use varied from 0.24 to 0.41 gal/hr. Fuel-use rates are typically lowest in mild weather, highest in hot or cold weather, and depend on engine speed (revolutions per minute [RPM]). Compared with the base engine, APU fuel use and emissions of carbon dioxide (CO2) and sulfur dioxide (SO2) are lower by 36–47%. Oxides of nitrogen (NOx) emissions are lower by 80–90%. Reductions in particulate matter (PM), carbon monoxide (CO), and hydrocarbon emissions vary from approximately 10 to over 50%. SP leads to more substantial reductions, except for SO2. The actual achievable reductions will be lower because only a fraction of base engine usage will be replaced by APUs, SP, or both. Recommendations are made for reducing base engine fuel use and emissions, accounting for variability in fuel use and emissions reductions, and further work to quantify real-world avoided fuel use and emissions.