The environmental and cost implications of solar energy preferences in Renewable Portfolio Standards

Many state-level Renewable Portfolio Standards (RPS) include preferences for solar generation, with goals of increasing the generation diversity, reducing solar costs, and encouraging local solar industries. Depending on their policy design, these preferences can impact the RPS program costs and emissions reduction. This study evaluates the impact of these policies on costs and emissions, coupling an economic dispatch model with optimized renewable site selection. Three policy designs of an increased RPS in Michigan are investigated: (1) 20% Solar Carve-Out, (2) 5% Distributed Generation Solar Carve-Out, and (3) 3× Solar Multiplier. The 20% Solar Carve-Out scenario was found to increase RPS costs 28%, while the 5% Distributed Generation Solar Carve-Out increased costs by 34%. Both of these solar preferences had minimal impact on total emissions. The 3× Solar Multiplier decreases total RPS program costs by 39%, but adds less than half of the total renewable generation of the other cases, significantly increasing emissions of CO₂, NO_x, and SO₂ relative to an RPS without the solar credit multiplier. Sensitivity analysis of the installed cost of solar and the natural gas price finds small changes in the results of the Carve-Out cases, with a larger impact on the 3× Solar Multiplier.     

Internalisation of external cost in the power generation sector: Analysis with Global Multi-regional MARKAL model

The Global MARKAL-Model (GMM), a multi-regional “bottom-up” partial equilibrium model of the global energy system with endogenous technological learning, is used to address impacts of internalisation of external costs from power production. This modelling approach imposes additional charges on electricity generation, which reflect the costs of environmental and health damages from local pollutants (SO₂, NO_x) and climate change, wastes, occupational health, risk of accidents, noise and other burdens. Technologies allowing abatement of pollutants emitted from power plants are rapidly introduced into the energy system, for example, desulphurisation, NO_x removal, and CO₂ scrubbers. The modelling results indicate substantial changes in the electricity production system in favour of natural gas combined cycle, nuclear power and renewables induced by internalisation of external costs and also efficiency loss due to the use of scrubbers. Structural changes and fuel switching in the electricity sector result in significant reduction of emissions of both local pollution and CO₂ over the modelled time period. Strong decarbonisation impact of internalising local externalities suggests that ancillary benefits can be expected from policies directly addressing other issues then CO₂ mitigation. Finally, the detailed analysis of the total generation cost of different technologies points out that inclusion of external cost in the price of electricity increases competitiveness of non-fossil generation sources and fossil power plants with emission control.     

An evaluation of biomass co-firing in Europe

Reduction of the emissions of greenhouses gases, increasing the share of renewable energy sources (RES) in the energy balance, increasing electricity production from renewable energy sources and decreasing energy dependency represent the main goals of all current strategies in Europe. Biomass co-firing in large coal-based thermal power plants provides a considerable opportunity to increase the share of RES in the primary energy balance and the share of electricity from RES in gross electricity consumption in a country. Biomass-coal co-firing means reducing CO₂ and SO₂, emissions and it may also reduce NO_x emissions, and also represents a near-term, low-risk, low-cost and sustainable energy development. Biomass-coal co-firing is the most effective measure to reduce CO₂ emissions, because it substitutes coal, which has the most intensive CO₂ emissions per kWh electricity production, by biomass, with a zero net emission of CO₂. Biomass co-firing experience worldwide are reviewed in this paper. Biomass co-firing has been successfully demonstrated in over 150 installations worldwide for most combinations of fuels and boiler types in the range of 50–700 MWe, although a number of very small plants have also been involved. More than a hundred of these have been in Europe. A key indicator for the assessment of biomass co-firing is intrduced and used to evaluate all available biomass co-firing technologies.     

Internalizing externalities into capacity expansion planning: The case of electricity in Vietnam

This paper examines the impacts of including external costs such as environmental and health damages from power production on power generation expansion planning in Vietnam. Using the MARKAL model and covering a 20-year period to 2025, the study shows that there are substantial changes in the generation structure in favor of renewable energy technologies and other low emitting technologies. These changes lead to a reduction in fossil fuel requirements, and consequently, a reduction of CO₂, NO_x, SO₂, and PM emissions which could be expected to also reduce the associated environmental and human health impacts. The avoided external costs would be equivalent to 4.4 US cent/kWh. However, these gains are not free as the additional electricity production cost would be around 2.6 US cent/kWh higher if the switch to more expensive, but lower emitting technologies were made. The net benefit of internalizing these externalities is thus around 1.8 US cent/kWh.     

Does a regional greenhouse gas policy make sense? A case study of carbon leakage and emissions spillover

The Regional Greenhouse Gas Initiative (RGGI) is a state-level effort by ten northeast states in the U.S. to control CO₂ emissions from the electric sector. The approach adopted by RGGI is a regional cap-and-trade program, which sets a maximal annual amount of regional CO₂ emissions that can be emitted from the electric sector. However, incoherence of the geographic scope of the regional electricity market is expected to produce two undesirable consequences: CO₂ leakage and NO_x and SO₂ emissions spillover. This paper addresses these two issues using transmission-constrained electricity market models. The results show that although larger CO₂ leakage is associated with higher allowance prices, it is negatively related to CO₂ prices if measured in percentage terms. On the other hand, SO₂ and NO_x emissions spillover increase in commensurate with CO₂ allowance prices. Demand elasticity attenuates the effect of emissions trading on leakage and emissions spillover. This highlights the difficulties of designing a regional or local climate policy.     

Experimental studies on cofiring of coal and biomass blends in India

Concerns regarding the potential global environmental impacts of fossil fuels used in power generation and other energy supplies are increasing worldwide. One of the methods of mitigating these environmental impacts is increasing the fraction of renewable and sustainable energy in the national energy usage. A number of techniques and methods have been proposed for reducing gaseous emissions of NO_x,SO₂ and CO₂ from fossil fuel combustion and for reducing costs associated with these mitigation techniques. Some of the control methods are expensive and therefore increase production costs. Among the less expensive alternatives, cofiring has gained popularity with the electric utility producers. This paper discusses the ‘gaseous emission characteristics namely NO_x,SO₂, suspended particulate matter and other characteristics like specific fuel consumption, total fuel required, actual and equivalent evaporation, total cost of fuel, etc. from a 18.68 MW power plant with a travelling grate boiler, when biomass was cofired with bituminous coal in three proportions of 20%, 40% and 60% by mass. Bagasse, wood chips (Julia flora), sugarcane trash and coconut shell are the biomass fuels cofired with coal in this study.     

Estimate of ecological efficiency for thermal power plants in Brazil

Global warming and the consequent climatic changes that will come as a result of the increase of CO₂ concentration in the atmosphere have increased the world’s concern regarding reduction of these emissions, mainly in developed countries that pollute the most. Electricity generation in thermal power plants, as well as other industrial activities, such as chemical and petrochemical ones, entail the emission of pollutants that are harmful to humans, animals and plants. The emissions of carbon oxides (CO and CO₂) and nitrous oxide (N₂O) are directly related to the greenhouse effect. The negative effects of sulfur oxides (SO₂ and SO₃ named SO_x) and nitrogen oxides (NO_x) are their contribution to the formation of acid rain and their impacts on human health and on the biota in general. This study intends to evaluate the environmental impacts of the atmospheric pollution resulting from the burning of fossil fuels. This study considers the emissions of CO₂, SO_x, NO_x and PM in an integral way, and they are compared to the international air quality standards that are in force using a parameter called ecological efficiency (ε).     

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.     

The environmental and efficiency effects of restructuring on the electric power sector in the United States: An empirical analysis

Recent measures to restructure the electric power sector in different US states have raised the interest of policy makers, commentators, and the general public as to the actual impact of restructuring on both the economy and the environment. This paper focuses on two aspects of restructuring, namely its potential impact on the efficiency of electricity generation and air pollution. Our empirical results suggest that restructuring contributes to improved efficiency of electricity generation and better air quality through reduced electricity-induced sulfur dioxide (SO₂) and carbon dioxide (CO₂) emissions, although no effect was found for emissions of nitrous oxides (NO_x). These results, in turn could have important implications for policy in this area.     

LCI (Life cycle inventory) analysis of fuels and electricity generation in Singapore

This article offers a unique three-stage approach in LCI analysis for generating the environmental profile of electricity generation in Singapore. The first stage focuses on fuels delivered to Singapore, next on electricity generated from various types of power production plants. The third stage integrates the entire life cycle study. The final gate-to-gate results show that the total CO₂ emissions from the national grid are 455.6 kg CO₂ per MWh without any loss in transmission and 467.0 kg CO₂ per MWh with 2.5% losses. The results for the entire cradle-to-gate energy production are: 586.3 kg CO₂ per MWh without considering any losses and 601.0 kg CO₂ per MWh with 2.5% transmission loss. For the rest of the LCI, the cradle-to-gate results (per MWh) are kg 0.19 CO (carbon monoxide), 0.06 kg N₂O (nitrous oxide), 1.94–1.99 kg NO_x (nitrogen oxides), 2.94–3.01 kg SO_x (sulphur oxides), 0.064–0.066 kg VOC (volatile organic compounds) and 0.078–0.080 kg PM (particulate matters). From gate-to-gate, the results are 0.12 kg CO, 0.0016 kg N₂O, 1.42–1.46 kg NO_x, 2.56–2.62 kg SO_x, 0.033–0.034 kg VOC and 0.067–0.069 kg PM. Emissions of CO₂ from energy generation, climate change mitigation and policies for energy security are also discussed.     

Generating efficiency and emissions of a spark-ignition gas engine generator fuelled with biogas–hydrogen blends

We investigated the generating efficiency and pollutant emissions of a four-stroke spark-ignition gas engine generator operating on biogas–hydrogen blends of varying excess air ratios and hydrogen concentrations. Experiments were carried out at a constant engine speed of 1200 rpm and a constant electric power output of 10 kW. The experimental results showed that the peak values of generating efficiency, maximum cylinder pressure, and NO_x emissions were elevated at an excess air ratio of around 1.2 as the hydrogen concentration was increased. CO₂ emissions decreased as the excess air ratio and hydrogen concentration increased, due to lean-burn conditions and hydrogen combustion. An efficiency per NO_x emissions ratio (EPN) was defined to consider the relationship between the generating efficiency and NO_x emissions. A maximum EPN value of 0.7502 was obtained with a hydrogen concentration of 15%, for an excess air ratio of 2.0. At this EPN value, the NO_x and CO₂ emissions were 39 ppm and 1678.32 g/kWh, respectively, and the generating efficiency was 29.26%. These results demonstrated that the addition of hydrogen to biogas enabled the effective generation of electricity using a gas engine generator through lean-burn combustion.     

Reductions in emissions of local air pollutants and co-benefits of Chinese energy policy: a Shanghai case study

To better understand the reductions in local air pollution that will result from the implementation of current Chinese energy policy, as well as the co-benefit for greenhouse-gas emission reductions, a Shanghai case study was conducted. The MARKAL model was used to forecast energy consumption and emissions of local air pollutants under different energy policy scenarios and also to analyze the associated reductions in CO₂ emissions. The results show that energy policies in Shanghai will significantly reduce SO₂ and PM₁₀ emissions and will also achieve the co-benefit of mitigating the increase of CO₂ emissions. In energy policy scenarios, SO₂ emissions during the period 2000–2020 will maintain the same level as in 2000; and the annual rate of increase of CO₂ emissions will be reduced to 1.1–1.2%, compared with 2.7% under a business-as-usual scenario. The problem for the future will be NO_x emissions, which are projected to increase by 60–70% by 2020, due to expansion of the transportation system.     

Reduction of air pollutant emissions using renewable energy sources for power generation in Cyprus

In this paper, the options of using Renewable Energy Sources (RES) in the power system of Cyprus are examined in order to reduce air pollutant emissions. Power generation is the major contributor to total emissions in Cyprus with a share of 36% in carbon dioxide (CO₂), 62% in sulfur dioxide (SO₂), 20% in nitrogen oxides (NO_x) and 55% in nitrous oxide (N₂O) emission according to the emission inventory for the year 2002. The emissions reduction potential in the energy system of Cyprus is notable since the use of RES for power generation has so far been negligible. The national action plan for the promotion of electricity production from RES for the years 2009–2013 includes large-scale projects of total capacity target 211 MW_el, and in case is accomplished, there will be significant production of electricity, which is estimated to 11.2% of 2008 gross production. The resulting reduction of air pollutant emissions corresponds to 453 kt/yr of CO₂, 4.69 kt/yr of SO₂, 1.21 kt/yr of NO_x, 0.26 kt/yr of N₂O emissions and exceeds the emissions of Moni power station, the oldest in Cyprus and the one with the lower efficiency. Emissions reduction potential is even larger, since additional measures for rational use of electricity together with RES applications in final consumption sectors could contribute to decrease the demanded amount of electricity.     

Unintended consequences of cap-and-trade? Evidence from the Regional Greenhouse Gas Initiative

Cap-and-trade programs are designed to minimize the overall cost of pollution control by effectively allowing firms with low abatement costs to reduce emissions on behalf of those with higher abatement costs. However, these trades redistribute where emissions are generated, which has important implications for welfare because many pollutants have differential environmental and health impacts depending on where they are emitted. This paper compiles and analyzes a national data set of power plant emissions in order to assess how the Regional Greenhouse Gas Initiative (RGGI), a carbon dioxide (CO₂) cap-and-trade program involving nine states in the United States, impacts the emissions and damages from copollutants. Our results suggest that, in addition to achieving its goal of reducing CO₂, the program has lowered the quantity of sulfur dioxide (SO₂) emissions as well as associated damages in the policy region. However, two factors diminish the overall benefits from the program. First, within the RGGI region, trading shifts electricity generation to locations with higher marginal damages for SO₂. Second, there is leakage of electricity generation and emissions to nearby states, although this latter effect is more modest than ex ante analyses predicted.     

The expansion of electricity generation from renewable energies in Germany: A review based on the Renewable Energy Sources Act Progress Report 2007 and the new German feed-in legislation

The expansion of electricity generation from renewable sources in Germany is promoted by the Erneuerbare-Energien-Gesetz (EEG), which was last amended in June 2008. In a review of the EEG the political parameters, the progress achieved, and the impacts of the Act itself are set out. This Progress Report addresses cross-sectoral aspects, notably CO₂ emissions reduction, job creation, investment and turnover in the renewables industry, and that industry's prospects for the future. Trends in the individual renewables sectors are described and policy recommendations formulated, as appropriate, on this basis. The policy recommendations have been incorporated into the new EEG from 6 June 2008.     

New sources will drive global emissions

Nearly all policy initiatives to mitigate climate change have adopted the cap and trade approach, perhaps because this approach has worked so well for reducing SO_x and NO_x from existing power plants in the US. However, new sources, not existing sources, will be primarily responsible for global CO₂ emissions in the 21st century, since new sources provide for growth and replace existing sources at the end of their useful lives. Hence, policy initiatives should be designed for new sources rather than for existing sources, and cap and trade may not be the best approach.     

Life cycle inventory analysis for electricity in Korea

A life cycle inventory analysis (LCI) database that encompasses the entire Korean electrical energy grid was developed. The CO₂ emission per functional unit of electricity, 1 kWh of usable electricity, was 0.49 kg/f.u. Contribution of direct emission of CO₂ to the total CO₂ emission was around 95%. In the case of emissions of SO_x, NO_x, and PM, contribution of the upstream processes including raw energy material extraction, transport, and fuel processing to the total emissions were 29%, 26%, and 43%, respectively. Emissions of air pollutants from power generation or direct emissions are much greater in quantity than those from the upstream processes. On the other hand, the opposite is true for the emissions of water pollutants. Bituminous coal was the largest source of emissions of air and water pollutants including CO₂. Natural gas was the best fuel and anthracite coal was the worst fuel with respect to the direct and upstream emissions of air and water pollutants and wastes.     

ACROPOLIS: An example of international collaboration in the field of energy modelling to support greenhouse gases mitigation policies

Energy models are considered as valuable tools to assess the impact of various energy and environment policies. The ACROPOLIS initiative, supported by the European Commission and the International Energy Agency, used up to 15 energy models to simulate and evaluate selected policy measures and instruments and then compare their impacts on energy systems essentially in terms of costs of greenhouse gas emissions (GHG) reduction and energy technology choice. Four case studies are formulated considering policies and measures on renewable portfolio schemes and internationally tradable green certificates, emissions trading and global GHG abatement target, energy efficiency standards and internalisation of external costs. The main focus of the project is on the electricity sector. From a large set of quantified results, ACROPOLIS provides an international scientific consensus, on some key issues, which could be useful in assessing and designing energy and environment policies at the world, European and national/regional levels. It concludes that the Kyoto targets (and their continuation beyond 2010 in specific scenarios) could be achieved at a cost around 1% of GDP through global emissions trading, indicating also that this flexibility mechanism is a more cost-effective instrument for GHG mitigation than meeting the goal domestically without trade. It demonstrates that internalising external costs through a price increase reduces local pollutants (SO_x, NO_x, and others) and it produces other benefits such as triggering the penetration of clean technologies in addition to the curbing of CO₂ emissions.     

Supply- and demand-side effects of power sector planning with demand-side management options and SO2 emission constraints

This paper examines the implications of SO₂ emission mitigation constraints in the power sector planning in Indonesia—a developing country—during 2003–2017 from a long term integrated resource planning perspective. A decomposition model is developed to assess the contributions of supply- and demand-side effects to the total changes in CO₂, SO₂ and NO_x emissions from the power sector due to constraints on SO₂ emissions. The results of the study show that both the supply- and demand-side effects would act towards the reduction of CO₂, SO₂ and NO_x emissions. However, the supply-side effect would play the dominant role in emission mitigations from the power sector in Indonesia. The average incremental SO₂ abatement cost would increase from US$ 970 to US$ 1271 per ton of SO₂, while electricity price would increase by 2–18% if the annual SO₂ emission reduction target is increased from 10% to 25%.     

The air quality and human health effects of integrating utility-scale batteries into the New York State electricity grid

In a restructured electricity market, utility-scale energy storage technologies such as advanced batteries can generate revenue by charging at low electricity prices and discharging at high prices. This strategy changes the magnitude and distribution of air quality emissions and the total carbon dioxide (CO₂) emissions. We evaluate the social costs associated with these changes using a case study of 500 MW sodium-sulfur battery installations with 80% round-trip efficiency. The batteries displace peaking generators in New York City and charge using off-peak generation in the New York Independent System Operator (NYISO) electricity grid during the summer. We identify and map charging and displaced plant types to generators in the NYISO. We then convert the emissions into ambient concentrations with a chemical transport model, the Particulate Matter Comprehensive Air Quality Model with extensions (PMCAM_x). Finally, we transform the concentrations into their equivalent human health effects and social benefits and costs. Reductions in premature mortality from fine particulate matter (PM_2.5) result in a benefit of 4.5 ¢ kWh⁻¹ and 17 ¢ kWh⁻¹ from displacing a natural gas and distillate fuel oil fueled peaking plant, respectively, in New York City. Ozone (O₃) concentrations increase due to decreases in nitrogen oxide (NO_x) emissions, although the magnitude of the social cost is less certain. Adding the costs from charging, displacing a distillate fuel oil plant yields a net social benefit, while displacing the natural gas plant has a net social cost. With the existing base-load capacity, the upstate population experiences an increase in adverse health effects. If wind generation is charging the battery, both the upstate charging location and New York City benefit. At $20 per tonne of CO₂, the costs from CO₂ are small compared to those from air quality. We conclude that storage could be added to existing electricity grids as part of an integrated strategy from a human health standpoint.