Determining marginal electricity for near-term plug-in and fuel cell vehicle demands in California: Impacts on vehicle greenhouse gas emissions

California has taken steps to reduce greenhouse gas emissions from the transportation sector. One example is the recent adoption of the Low Carbon Fuel Standard, which aims to reduce the carbon intensity of transportation fuels. To effectively implement this and similar policies, it is necessary to understand well-to-wheels emissions associated with distinct vehicle and fuel platforms, including those using electricity. This analysis uses an hourly electricity dispatch model to simulate and investigate operation of the current California grid and its response to added vehicle and fuel-related electricity demands in the near term. The model identifies the “marginal electricity mix” - the mix of power plants that is used to supply the incremental electricity demand from vehicles and fuels - and calculates greenhouse gas emissions from those plants. It also quantifies the contribution from electricity to well-to-wheels greenhouse gas emissions from battery-electric, plug-in hybrid, and fuel cell vehicles and explores sensitivities of electricity supply and emissions to hydro-power availability, timing of electricity demand (including vehicle recharging), and demand location within the state. The results suggest that the near-term marginal electricity mix for vehicles and fuels in California will come from natural gas-fired power plants, including a significant fraction (likely as much as 40%) from relatively inefficient steam- and combustion-turbine plants. The marginal electricity emissions rate will be higher than the average rate from all generation - likely to exceed 600 gCO₂ equiv. kWh⁻¹ during most hours of the day and months of the year - and will likely be more than 60% higher than the value estimated in the Low Carbon Fuel Standard. But despite the relatively high fuel carbon intensity of marginal electricity in California, alternative vehicle and fuel platforms still reduce emissions compared to conventional gasoline vehicles and hybrids, through improved vehicle efficiency.     

Interactions between electricity-saving measures and carbon emissions from power generation in England and Wales

The relationship between electricity demand reduction and the consequent change in carbon emissions is central to greenhouse gas emissions policy. This paper examines this relationship for the power system of England and Wales. Previous analysis showed that the commonly used conversion factor based on the system average emission factor significantly underestimates these savings (Hitchin and Pout, 2002. The carbon intensity of electricity: how many kgC per kWhe?. Building Serv. Eng. Res. Technol. 23(4)). Thus any policy analysis based on the system-average emission factor will under-estimate the potential for carbon savings from reductions in electricity demand. The present paper extends the previous analysis by using more detailed modelling to explore differences between demand reductions of differing load shape and magnitude; and the sensitivity of these figures to changes of the fuel mix of the generation system.     

Influence of massive heat‐pump introduction on the electricity‐generation mix and the GHG effect—Belgian case study

To evaluate the environmental impact of massive heat‐pump introduction on greenhouse gas (GHG) emissions, dynamic simulations of the overall electricity‐generation system have been performed for Belgium. The simulations are carried out with Promix, a tool that models the overall electricity‐generation system. For comparison, three heating devices are considered, namely conventional boilers, heat pumps and electrical resistance heating. The introduction of electric heating at the expense of classic heating increases the demand for electricity and generates a shift of emissions from fossil‐fuel heating systems to electrical power plants. The replaced classic fossil‐fuel‐fired heating represents emissions of about 300 kton. With regard to the heat‐pump scenarios, both direct heat‐pump heating with a coefficient of performance (COP) of 2.5 and accumulation heat‐pump heating with a COP of 5 are investigated. The results of the simulations reveal that the massive introduction of heat‐pump heating is favourable to the environment. In Belgium, the largest reductions in GHG emissions occur with heat pumps for direct heating, combined with newly commissioned combined cycle (CC) gas‐fired plants or with accumulation heat‐pump heating. These scenarios bring about overall GHG emission reductions of approximately 200 kton compared with the reference case with conventional heating for the years 2000 and 2010. The amount of additional electricity‐related emissions depends on the considered heating device. In 2010, the scenario with accumulation heat pumps results in an overall decrease of Belgian GHG emissions by 0.15% compared with the reference scenario. The expansion of the electricity‐generation system with new CC plants has an important favourable impact on GHGs as well. In most cases, the combination of higher electricity demand and the construction of new gas‐fired CC plants will lead to lower overall GHG emissions. Copyright © 2007 John Wiley & Sons, Ltd.     

A stochastic‐fuzzy programming model with soften constraints for electricity generation planning with greenhouse‐gas abatement

Increased atmospheric CO₂ concentration is widely being considered as the main driving factor that causes the phenomenon of global warming, due to the ever‐boosting use of fossil fuels. In this study, a fuzzy‐stochastic programming model with soft constraints (FSP‐SC) is developed for electricity generation planning and greenhouse gas (GHG) abatement in an environment with imprecise and probabilistic information. The developed FSP‐SC is applied to a case study of long‐term planning of a regional electricity generation system, where integer programming technique is employed to facilitate dynamic analysis for capacity expansion within a multi‐period context to satisfy increasing electricity demand. The results indicate different relaxation levels can lead to changed electricity generation options, capacity expansion schemes, system costs, and GHG emissions. Several sensitivity analyses are also conducted to demonstrate that relaxation of different constraints have different effects on system cost and GHG emission. Tradeoffs among system costs, resource availabilities, GHG emissions, and electricity‐shortage risks can also be tackled with the relaxation levels for the objective and constraints. Copyright © 2012 John Wiley & Sons, Ltd.     

Sustainable energy system design with distributed renewable resources considering economic,environmental and uncertainty aspects

Electricity generation using renewable energy generation technologies is one of the most practical alternatives for network planners in order to achieve national and international Greenhouse Gas (GHG) emission reduction targets. Renewable Distributed Generation (DG) based Hybrid Energy System (HES) is a sustainable solution for serving electricity demand with reduced GHG emissions. A multi-objective optimisation technique for minimising cost, GHG emissions and generation uncertainty has been proposed in this paper to design HES for sustainable power generation and distribution system planning while considering economic and environmental issues and uncertainty in power availability of renewable resources. Life cycle assessment has been carried out to estimate the global warming potential of the embodied GHG emissions from the electricity generation technologies. The uncertainty in the availability of renewable resources is modelled using the method of moments. A design procedure for building sustainable HES has been presented and the sensitivity analysis is conducted for determining the optimal solution set.     

Climate change mitigation with integration of renewable energy resources in the electricity grid of New South Wales,Australia

The implementation of climate change mitigation strategies may significantly affect the current practices for electricity network operation. Increasing penetration of renewable energy generation technologies into electricity networks is one of the key mitigation strategies to achieve greenhouse gas emission reduction targets. Additional climate change mitigation strategies can also contribute to emission reduction thereby supplementing the renewable energy generation participation, which may be limited due to technical constraints of the network. In this paper, the penetration requirements for different renewable energy generation resources are assessed while concurrently examining other mitigation strategies to reduce overall emissions from electricity networks and meet requisite targets. The impacts of climate change mitigation strategies on the demand and generation mix are considered for facilitating the penetration of renewable generation. New climate change mitigation indices namely change in average demand, change in peak demand, generation flexibility and generation mix have been proposed to measure the level of emission reduction by incorporating different mitigation strategies. The marginal emissions associated with the individual generation technologies in the state of New South Wales (NSW) are modelled and the total emissions associated with the electricity grid of NSW are evaluated.     

Assessing the potential of fuel cell-powered and battery-powered forklifts for reducing GHG emissions using clean surplus power; a game theory approach

This work aims at developing a game theory model for assessing the potential of fuel cell-powered and battery-powered forklifts for reducing GHG emissions in the province of Ontario, Canada. Two stakeholders are considered in the developed model: government and energy consumer. The energy consumer, which is assumed to be an industrial facility, operates 150 diesel forklifts but has the option of replacing them with fuel cell-powered and battery-powered forklifts. The government can encourage this replacement by allocating a percentage of Ontario's surplus power to the energy consumer at a discounted price. The discount is assumed to be exempting the energy consumer from paying the global adjustment. As a result, the energy consumer only pays the hourly Ontario electricity price when discounted power is available. Discounted electricity will decrease the cost of operating battery-powered and fuel cell-powered forklifts for the energy consumer and will encourage it to use those technologies instead of diesel forklifts. The government has an incentive to pursue such policy as the replacement of diesel forklifts with fuel cell-powered and battery-powered forklifts will reduce GHG emissions and subsequently, the social cost of carbon in the province. The reults of our modeling show that when the government does not allocate discounted power to the energy consumer, energy consumer does not reduce emissions and keeps using its 150 diesel forklifts. However, when the government provides 0.1% of Ontario's surplus power at each hour to the energy consumer at a discounted price, the energy consumer replaces 31 of its diesel forklifts with battery-powered forklifts. When the percentage of discounted power is 0.6% of Ontario's surplus power at each hour, energy consumer replaces 91 of its diesel forklifts with battery-powered forklifts and 54 of its diesel forklifts with fuel cellpowered forklifts.A policy of discounting surplus power to encourage replacing diesel forklifts with battery-powered and fuel cell-powered forklifts is shown to benefit both stakeholders in the system. Our analysis also shows that the deployment of both fuel-cell powered and battery-powered forklifts is effective in reducing GHG emissions in Ontario when surplus clean power is available. Battery-powered forklifts are more cost-effective when lower levels of discounted power are available; however, with an increase in the level of available discounted power, fuel cell-powered forklifts become more cost-effective technologies compared to battery-powered forklifts.     

Using strong sustainability to optimize electricity generation fuel mixes

This work represents a contribution to the field of sustainable electricity system design by using an optimization tool to specify the final mix composition, subject to the constraints of: emissions that are within the biocapacity of the region; a diverse and robust electricity supply system; and supply that at least meets current demand. The 25-country European Union (EU-25) is used as a case study. All the goals, save diversity, can be met by re-structuring the current fuel mix, thus maintaining current consumption levels. The diversity target is only met when consumption is reduced by 10–15% and the constraint on maximum material throughput is relaxed. Re-structuring the mix and reducing consumption is insufficient to achieve a sustainable EU carbon footprint. However, the solution proposed singlehandedly allows the EU to meet its Kyoto emissions target as well as its 2007 policy of a reduction of 20% in greenhouse gas emissions by 2020.     

Wind power and CO2 emissions in the Irish market

This paper presents an empirical analysis of the displacement of CO₂ emissions associated with wind generation in the Irish electricity market between December 2013 and May 2017. We find that the average marginal effect of an additional MWh of wind generation corresponds to a reduction in CO₂ emissions of 0.401 tonnes in Ireland (All-Island system) and 0.459 tonnes when accounting also for the emissions offset in Great Britain. We also find that, for each given demand level, the amount of emissions displaced by wind varies with the wind level. In particular, overall the amount of total (domestic plus external) CO₂ emissions offset by a MWh of wind generation increases as the wind generation level increases, a result which suggests that as wind generation capacity increases the effectiveness of wind in displacing CO₂ may be retained. However, when accounting exclusively for the effects of wind generation on domestic emissions, we observe that the effectiveness of wind in displacing emissions may decrease as the amount of wind generation increases further. As the effects of CO₂ as a GHG are independent of the location where it is emitted, our work also highlights that accounting for reductions in emissions due to a reduction of imports from, or an increase in exports to, interconnected markets is crucial in this type of analysis due to the potential for underestimating the effects of wind on emissions savings when only national emissions are accounted for. The Irish government has a target for 40% of total electricity generation to be produced by renewable energy sources by 2020 which, according to institutional reports, may entail an additional 25% to 35% increase in wind generation capacity from the present levels. Accordingly, our findings are particularly relevant for policy making since they do not support one of the arguments against further investment in wind, namely that the corresponding environmental benefits in the form of emissions savings are reduced.     

Tracking electricity generation attributes in Europe

Tracking electricity generation attributes can yield detailed information on the used electricity generating technologies, such as per unit fuel consumption and emissions to the environment. The policy context matters for defining the attributes to be tracked. Evolving experience with tracking greatly facilitates the implementation of reliable tracking systems. Some EU Member States have already gained experience with electronically tracked generation attributes for the purpose of disclosing the generation mix to the consumer. Another major application is the use for facilitation of support systems for renewable electricity. There are factors rendering the introduction of tracking generation attributes in Europe no easy task. The main problem is the widely varying initiatives among EU Member States to implement legislation on Guarantees of Origin and disclosure, as this greatly complicates trans-border transfers of generation attributes. The amount of electricity traded makes it difficult to link generation to consumption under “contract-tied tracking”, while this is of no concern under “de-linked tracking”. The key towards overcoming the aforementioned barriers is harmonisation of schemes for tracking generation attributes.     

Residential past and future energy consumption: Potential savings and environmental impact

In order to identify main drivers behind changes in electricity and fuel consumptions in the household sector in Jordan, two empirical models are developed based on multivariate linear regression analysis. In addition, this paper analyzes and evaluates impacts of introducing some efficient measures, such as high efficiency lightings and solar water heating systems, in the housing stock, on the future fuel and electricity demands and associated reduction in GHG emissions. It was found that fuel unit price, income level, and population are the most important variables that affect demand on electrical power, while population is the most important variable in the case of fuel consumption. Obtained results proved that the multivariate linear regression models can be used adequately to simulate residential electricity and fuel consumptions with very high coefficient of determination. Without employing most effective energy conservation measures, electricity and fuel demands are expected to rise by approximately 100% and 23%, respectively within 10 years time. Consequently, associated GHG emissions resulting from activities within the residential sector are predicted to rise by 59% for the same period. However, if recommended energy management measures are implemented on a gradual basis, electricity and fuel consumptions as well as GHG emissions are forecasted to increase at a lower rate.     

Fuel-cycle analysis of early market applications of fuel cells: Forklift propulsion systems and distributed power generation

Forklift propulsion systems and distributed power generation are identified as potential fuel cell applications for near-term markets. This analysis examines fuel cell forklifts and distributed power generators, and addresses the potential energy and environmental implications of substituting fuel-cell systems for existing technologies based on fossil fuels and grid electricity. Performance data and the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model are used to estimate full fuel-cycle emissions and use of primary energy sources. The greenhouse gas (GHG) impacts of fuel-cell forklifts using hydrogen from steam reforming of natural gas are considerably lower than those using electricity from the average U.S. grid. Fuel cell generators produce lower GHG emissions than those associated with the U.S. grid electricity and alternative distributed combustion technologies. If fuel-cell generation technologies approach or exceed the target efficiency of 40%, they offer significant reduction in energy use and GHG emissions compared to alternative combustion technologies.     

Plug-in hybrid vehicle GHG impacts in California: Integrating consumer-informed recharge profiles with an electricity-dispatch model

This paper explores how Plug-in Hybrid Vehicles (PHEVs) may reduce source-to-wheel Greenhouse Gas (GHG) emissions from passenger vehicles. The two primary advances are the incorporation of (1) explicit measures of consumer interest in and potential use of different types of PHEVs and (2) a model of the California electricity grid capable of differentiating hourly and seasonal GHG emissions by generation source. We construct PHEV emissions scenarios to address inherent relationships between vehicle design, driving and recharging behaviors, seasonal and time-of-day variation in GHG-intensity of electricity, and total GHG emissions. A sample of 877 California new vehicle buyers provide data on driving, time of day recharge access, and PHEV design interests. The elicited data differ substantially from the assumptions used in previous analyses. We construct electricity demand profiles scaled to one million PHEVs and input them into an hourly California electricity supply model to simulate GHG emissions. Compared to conventional vehicles, consumer-designed PHEVs cut marginal (incremental) GHG emissions by more than one-third in current California energy scenarios and by one-quarter in future energy scenarios—reductions similar to those simulated for all-electric PHEV designs. Across the emissions scenarios, long-term GHG reductions depends on reducing the carbon intensity of the grid.     

Survey of Western U.S. electric utility resource plans

We review long-term electric utility plans representing ~90% of generation within the Western U.S. and Canadian provinces. We address what utility planners assume about future growth of electricity demand and supply; what types of risk they consider in their long-term resource planning; and the consistency in which they report resource planning-related data. The region is anticipated to grow by 2% annually by 2020 – before Demand Side Management. About two-thirds of the utilities that provided an annual energy forecast also reported energy efficiency savings projections; in aggregate, they anticipate an average 6.4% reduction in energy and 8.6% reduction in peak demand by 2020. New natural gas-fired and renewable generation will replace retiring coal plants. Although some utilities anticipate new coal-fired plants, most are planning for steady growth in renewable generation over the next two decades. Most planned solar capacity will come online before 2020, with most wind expansion after 2020. Fuel mix is expected to remain ~55% of total generation. Planners consider a wide range of risks but focus on future demand, fuel prices, and the possibility of GHG regulations. Data collection and reporting inconsistencies within and across electric utility resource plans lead to recommendations on policies to address this issue.     

Electricity trade and GHG emissions: Assessment of Quebec's hydropower in the Northeastern American market (2006–2008)

Worldwide electricity sector reforms open up electricity markets and increase trades. This has environmental consequences as exports and imports either increase or decrease local production and consequently greenhouse gas (GHG) emissions. This paper's objective is to illustrate the importance of electricity trade's impact on GHG emissions by providing an estimate of the net GHG emissions resulting from these trades. To achieve this objective, Quebec hourly electricity exchanges with adjacent jurisdictions were examined over the 2006–2008 period. In order to associate a specific GHG emission quantity to electricity trades, hourly marginal electricity production technologies were identified and validated using the Ontario hourly output per power plant and information released in the Quebec adjacent system operator reports. It is estimated that over three years, imports into Quebec were responsible for 7.7 Mt of GHG, while Quebec hydropower exports avoided 28.3 Mt of GHG emissions. Hence, the net result is 20.6 Mt of avoided emissions over 2006–2008, or about 7 Mt per year, which corresponds to more than 8% of the Quebec yearly GHG emissions. When GHG emissions from all life cycle stages (resource extraction to end-of-life) are accounted for, the net avoided GHG emissions increase by 35%, to 27.9 Mt.     

Assessing the economic value of renewable distributed generation in the Northeastern American market

Incentive programs and tax rebates are commonly offered to offset the high initial costs of small-scale renewable energy systems (RES) and foster their implementation. However, the economic costs of RES grid integration must be fully known in order to determine whether such subsidies are justified. The objective of this paper is to assess the economic value of RES, including their environmental benefits, using hourly generation information in conjunction with hourly wholesale price data. Reaching the paper′s objective will provide a better estimate of the bias that could result from neglecting 1) the time pattern of the hourly wholesale price, 2) the impacts of carbon taxes on the hourly wholesale price and 3) the value of the marginal hourly GHG emissions. Selected RES include two types of grid-connected photovoltaic panels (3 kWp mono- and poly-crystalline) and three types of micro-wind turbines (1, 10 and 30 kW) modeled for different climatic conditions in the province of Quebec (Canada). The cost of electricity is based on the technical performance of these RES using a life cycle costing methodology. The economic value of RES electricity is estimated using the hourly wholesale electricity price in Northeastern American markets in 2006–2008. Results show that distributed generation (DG) has no economic benefits using the selected RES, even with a US$100/tonne of CO₂-equivalent carbon tax. This finding remains the same when the value of the avoided GHG emissions is fully internalized, except for one scenario (micro-wind 30 kW). Our results are key to understanding the extent to which subsidies for distributed RES can be economically sustainable when the latter are integrated into regional networks driven by centralized electricity production.     

Seamless electricity trade between Canada and US Northeast

We analyze how the wholesale electricity market deregulation could modify exchanges between three Canadian regions (Ontario, Quebec and New Brunswick) and two US regions (New York and New England), on the base of their loads and available resources when the regulatory change took place in 1997. We find that the pre-1997 exchanges already made possible fuel cost savings of $397.2 million per year while deregulation adds annual savings of $358.7 million. Canadian regions are the main beneficiaries under the assumption that exports are priced at the marginal costs of the importing regions. Imports from the Canadian regions, although significant, are not large enough to lower the marginal costs of the US regions. Hence electricity deregulation across the border should not significantly decrease prices in the US regions although the latter are becoming more dependent upon imports from Canada. Greenhouse gas emissions increase by 4.3 Mt CO₂ eq. in the wake of the open wholesale electricity market because of the low cost of coal, particularly in Ontario. Environmental concerns and the limited availability of additional hydroelectric power in Canada could change the trade patterns as electricity demand continue to grow.     

Comprehensive evaluation of effects of straw-based electricity generation: A Chinese case

Greater use of renewable energy is being aggressively promoted to combat climate change by the Chinese government and by other governments. Agricultural straw is the kind of renewable energy source that would become a pollution source if it is not well utilized. We select the Shiliquan straw-based electricity generation project in Shandong Province, China as a case and assess environmental externalities of straw utilization in power plants by using life-cycle analysis. Results show that straw-based electricity generation has far fewer greenhouse gas (GHG) emissions than that of coal-based electricity generation. Improvement in the energy efficiency of equipment used for straw’s pretreatment would lead to a decrease of GHG emissions and energy consumption in the life-cycle of straw-based electricity generation. In case 400 million tonnes of wasted straw in China could be used as a substitute for 200 million tonnes of coal, annually the straw 291 Terrawatt hours (TWh) of electricity could be generated, resulting in an annual total CO₂ emissions savings of 193 million tonnes. Straw-based electricity generation could be a high-potential alternative for electricity generation as well as an incentive for utilizing wheat straw instead of burning it in the field.     

Comparative assessment of future power generation technologies based on carbon price development

The long-term assessment of new electricity generation was performed for various long-run policy scenarios taking into account two main criteria: private costs and external GHG emission costs. Such policy oriented power generation technologies assessment based on carbon price and private costs of technologies can provide information on the most attractive future electricity generation technologies taking into account climate change mitigation targets and GHG emission reduction commitments for world regions.Analysis of life cycle GHG emissions and private costs of the main future electricity generation technologies performed in this paper indicated that biomass technologies except large scale straw combustion technologies followed by nuclear have the lowest life cycle GHG emission. Biomass IGCC with CO₂ capture has even negative life cycle GHG emissions. The cheapest future electricity generation technologies in terms of private costs in long-term perspective are: nuclear and hard coal technologies followed by large scale biomass combustion and biomass CHPs. The most expensive technologies in terms of private costs are: oil and natural gas technologies. As the electricity generation technologies having the lowest life cycle GHG emissions are not the cheapest one in terms of private costs the ranking of technologies in terms of competitiveness highly depend on the carbon price implied by various policy scenarios integrating specific GHG emission reduction commitments taken by countries and climate change mitigation targets.