Decarbonising city bus networks in Ireland with renewable hydrogen

This paper presents techno-economic modelling results of a nationwide hydrogen fuel supply chain (HFSC) that includes renewable hydrogen production, transportation, and dispensing systems for fuel cell electric buses (FCEBs) in Ireland. Hydrogen is generated by electrolysers located at each existing Irish wind farm using curtailed or available wind electricity. Additional electricity is supplied by on-site photovoltaic (PV) arrays and stored using lithium-ion batteries. At each wind farm, sizing of the electrolyser, PV array and battery is optimised system design to obtain the minimum levelised cost of hydrogen (LCOH). Results show the average electrolyser capacity factor is 64% after the integration of wind farm-based electrolysers with PV arrays and batteries. A location-allocation algorithm in a geographic information system (GIS) environment optimises the distributed hydrogen supply chain from each wind farm to a hypothetical hydrogen refuelling station in the nearest city. Results show that hydrogen produced, transported, and dispensed using this system can meet the entire current bus fuel demand for all the studied cities, at a potential LCOH of 5–10 €/kg by using available wind electricity. At this LCOH, the future operational cost of FCEBs in Belfast, Cork and Dublin can be competitive with public buses fuelled by diesel, especially under carbon taxes more reflective of the environmental impact of fossil fuels.     

A guide to the Kyoto protocol: a treaty with potentially vital strategic implications for the renewables industry

Why should renewables advocates care about the arcane business of multilateral climate negotiations? The answer is simple. Because these long-running and oft bogged-down talks have as their ultimate objective a goal with seismic implications for energy markets: substantial reductions in greenhouse gas emissions. Coming anywhere close to that goal would entail the creation of multi-hundred billion dollar markets in renewables in the years ahead. And in Kyoto last December, governments took a meaningful first step in that direction.This paper is a brief summary, and analysis of that first step. It concludes with some observations about immediate implications for the renewables industries.     

Prioritizing investment in residential energy efficiency and renewable energy—A case study for the U.S. Midwest

Residential building energy use is an important contributor to greenhouse gas emissions and in the United States represents about 20% of total energy consumption. A number of previous macro-scale studies of residential energy consumption and energy-efficiency improvements are mainly concerned with national or international aggregate potential savings. In this paper we look into the details of how a collection of specific homes in one region might reduce energy consumption and carbon emissions, with particular attention given to some practical limits to what can be achieved by upgrading the existing residential building stock. Using a simple model of residential, single-family home construction characteristics, estimates are made for the efficacy of (i) changes to behavioral patterns that do not involve building shell modifications; (ii) straightforward air-infiltration mitigation measures, and (iii) insulation measures. We derive estimates of net lifetime savings resulting from these measures, in terms of energy, carbon emissions and dollars. This study points out explicitly the importance of local and regional patterns in decision-making about what fraction of necessary regional or national emissions reduction might be accomplished through energy-efficiency measures and how much might need to concentrate more heavily on renewable or other carbon-free sources of energy.     

Natural hydrogen seeps identified in the North Perth Basin,Western Australia

Natural hydrogen seeps called fairy circles have been identified in Mali, Brazil, Russia, and United-States. Natural hydrogen is produced from a field in Mali for 7 years. The natural hydrogen system is still poorly understood and needs to be studied in new geological contexts as to streamline hypotheses on the system dynamics and elements into concepts. In Australia, numerous circular surface features, commonly called salt lakes or swaps, are visible from the sky but no existing work shows nor quantifies any hydrogen content in those features. In this study, we reviewed the existing literature on fairy circles as to determine and directly test with soil-gas measurements if hydrogen surface-emitting features are present in Australia. We determined best candidates to test with a multi-disciplinary approach linking geology, multi-physical imaging, and seismic interpretation. Soil-gas measurements showed persistent hydrogen concentration localized in the external ring of circular depressions aligned along the Darling Fault, a major crustal boundary between the granitic, mafic and ultramafic rocks of the Yilgarn Craton from the sedimentary rocks of the Perth Basin. This work is the proof that fairy circles, in the meaning of H₂ emitting structures, are present in Australia and opens the door to new prospectivity pathways by evaluating original hypotheses on natural hydrogen generation, migration pathways and entrapment. This geological setting promotes deep serpentinization of ultramafic rocks as well as oxidation of iron-rich Archean rocks and mafic dikes as potential hydrogen sources that are both of massive potential economic value. This hydrogen can circulate and be entrapped as aqueous hydrogen in low-salinity aquifers or migrate in gaseous phase in fault zones up to intermediate structural reservoir or to the surface.     

An engineering model for heating energy and emission assessment The case of North Karelia, Finland

This paper presents a regional engineering model for assessing space heating energies and related greenhouse gas emissions. The objective of the modeling is to improve the quality and quantity of heating energy and emission data, especially for the benefit of local decision making. The model incorporates fuel and energy statistics, building register data, demographic parameters and technical characters of heating into a single framework, allowing explorations of fuel and heat source changes, heating electricity procurement and energy conservation. The case area of the study is the province of North Karelia in Eastern Finland. A model structure, with calibration and evaluation procedures is presented, and extensive municipal estimates of heating energy and related greenhouse gas emission are produced. New indicators characterising the sustainability of heating energy use are introduced. These include municipal per capita estimates of heating energy and emissions as well as the determination of the shares of domestic and renewable energies in space heating.     

Preconditions and tools for cross-sectoral regional industrial GHG and energy efficiency policy—A Finnish standpoint

The aim of this paper is to develop an approach and tools for cross-sectoral regional industrial GHG and energy policies. These policies can be conducted at different levels of society. To achieve real results in energy efficiency improvements and in GHG reductions, the policies must be focused on the correct levels in society. In Finland, the province level seems to be a reasonable level for a policy targeted at industry. This paper proposes a category for the ways industry uses energy: building energy users, major users of electricity for process/production, major users of heat for process/production and direct combustion users. This approach gives opportunities for developing regional cooperation among different industries. The approach is also important between industries and society, so that there are integrated solutions which e.g. utilise district heating and biofuel potentials. The individual technologies like electric motors, pumps, fans, heat recovery equipment and boilers do not seem to have any significant potentials for improvements in energy efficiency by the EU target year 2020. However, there are opportunities but they are at system levels: how effectively the individual technologies are applied as a part of industrial systems. This fact supports the idea of energy use categorising.     

Greenhouse gas emissions in the nuclear life cycle: A balanced appraisal

In order to combat global warming, a detailed knowledge of the greenhouse gas (GHG) emissions associated with different energy conversion technologies is important. For nuclear energy, GHG emissions result from different process stages of the whole fuel cycle. A life-cycle assessment offers the possibility to properly calculate these emissions. In the past, both indirect energy use and GHG emissions were studied by many researchers. Most of the studies result in low indirect emissions comparable to wind turbines. However, some of the studies in the literature obtain high results adding up to a significant fraction of the direct emissions from a CCGT.     

Towards real energy economics: Energy policy driven by life-cycle carbon emission

Alternative energy technologies (AETs) have emerged as a solution to the challenge of simultaneously meeting rising electricity demand while reducing carbon emissions. However, as all AETs are responsible for some greenhouse gas (GHG) emissions during their construction, carbon emission “Ponzi Schemes” are currently possible, wherein an AET industry expands so quickly that the GHG emissions prevented by a given technology are negated to fabricate the next wave of AET deployment. In an era where there are physical constraints to the GHG emissions the climate can sustain in the short term this may be unacceptable. To provide quantitative solutions to this problem, this paper introduces the concept of dynamic carbon life-cycle analyses, which generate carbon-neutral growth rates. These conceptual tools become increasingly important as the world transitions to a low-carbon economy by reducing fossil fuel combustion. In choosing this method of evaluation it was possible to focus uniquely on reducing carbon emissions to the recommended levels by outlining the most carbon-effective approach to climate change mitigation. The results of using dynamic life-cycle analysis provide policy makers with standardized information that will drive the optimization of electricity generation for effective climate change mitigation.     

Forecasting based on sectoral energy consumption of GHGs in Turkey and mitigation policies

Recently, global warming and its effects have become one of the most important themes in the world. Under the Kyoto Protocol, the EU has agreed to an 8% reduction in its greenhouse gas (GHG) emissions by 2008–2012. The GHG emissions (total GHG, CO₂, CO, SO₂, NO₂, E (emissions of non-methane volatile organic compounds)) covered by the Protocol are weighted by their global warming potentials (GWPs) and aggregated to give total emissions in CO₂ equivalents. The main subject in this study is to obtain equations by the artificial neural network (ANN) approach to predict the GHGs of Turkey using sectoral energy consumption. The equations obtained are used to determine the future level of the GHG and to take measures to control the share of sectors in total emission. According to ANN results, the maximum mean absolute percentage error (MAPE) was found as 0.147151, 0.066716, 0.181901, 0.105146, 0.124684, and 0.158157 for GHG, SO₂, NO₂, CO, E, and CO₂, respectively, for the training data with Levenberg–Marquardt (LM) algorithm by 8 neurons. R² values are obtained very close to 1. Also, this study proposes mitigation policies for GHGs.     

Dynamics of the oil transition: Modeling capacity,depletion, and emissions

The global petroleum system is undergoing a shift to substitutes for conventional petroleum (SCPs). The Regional Optimization Model for Emissions from Oil Substitutes, or ROMEO, models this oil transition and its greenhouse gas impacts. ROMEO models the global liquid fuel market in an economic optimization framework, but in contrast to other models it solves each model year sequentially, with investment and production optimized under uncertainty about future prevailing prices or resource quantities. ROMEO includes more hydrocarbon resource types than integrated assessment models of climate change. ROMEO also includes the carbon intensities and costs of production of these resources. We use ROMEO to explore the uncertainty of future costs, emissions, and total fuel production under a number of scenarios. We perform sensitivity analysis on the endowment of conventional petroleum and future carbon taxes. Results show incremental emissions from production of oil substitutes of ≈ 0–30 gigatonnes (Gt) of carbon over the next 50 years (depending on the carbon tax). Also, demand reductions due to the higher cost of SCPs could reduce or eliminate these increases. Calculated emissions are highly sensitive to the endowment of conventional oil and less sensitive to a carbon tax.     

Sectoral trends in global energy use and greenhouse gas emissions

Integrated assessment models have been used to project both baseline and mitigation greenhouse gas emissions scenarios. Results of these scenarios are typically presented for a number of world regions and end-use sectors, such as industry, transport, and buildings. Analysts interested in particular technologies and policies, however, require more detailed information to understand specific mitigation options in relation to business-as-usual trends. This paper presents sectoral trend for two of the scenarios produced by the Intergovernmental Panel on Climate Change's Special Report on Emissions Scenarios. Global and regional historical trends in energy use and carbon dioxide emissions over the past 30 years are examined and contrasted with projections over the next 30 years. Macro-activity indicators are analyzed as well as trends in sectoral energy and carbon demand. This paper also describes a methodology to calculate primary energy and carbon dioxide emissions at the sector level, accounting for the full energy and emissions due to sectoral activities.     

Mitigating greenhouse gas emissions from China's cities: Case study of Suzhou

Knowledge of the factors driving greenhouse gas (GHG) emissions from cities is crucial to mitigating China's anthropogenic emissions. In this paper, the main drivers increasing GHG emissions from the Chinese city of Suzhou between 2005 and 2010 were identified and quantitatively analyzed using the Kaya identity and the log-mean Divisia index method. We found that economy and population were the major drivers of GHG emissions in Suzhou, having contributed 162.20% and 109.04%, respectively, to the increase in emissions. A decline in carbon intensity, which was caused by the declining energy intensity and an adjustment to the mixture of power and industrial structures, was the major determinant and accounted for a reduction of 171.24% in GHG emissions. Slowing and maintaining healthy growth rates of economy and population could be the primary and most effective means if Suzhou tries to curb the total emissions over the short term. It may be more realistic for Suzhou to control emissions by optimizing the economic structure for low-carbon industrial development because of the city's relative high energy requirements and low potential to mitigate GHGs by adjusting the energy mixture.     

Baseload wind energy: modeling the competition between gas turbines and compressed air energy storage for supplemental generation

The economic viability of producing baseload wind energy was explored using a cost-optimization model to simulate two competing systems: wind energy supplemented by simple- and combined cycle natural gas turbines (“wind+gas”), and wind energy supplemented by compressed air energy storage (“wind+CAES”). Pure combined cycle natural gas turbines (“gas”) were used as a proxy for conventional baseload generation. Long-distance electric transmission was integral to the analysis. Given the future uncertainty in both natural gas price and greenhouse gas (GHG) emissions price, we introduced an effective fuel price, p_NGeff, being the sum of the real natural gas price and the GHG price. Under the assumption of p_NGeff=$5/GJ (lower heating value), 650 W/m² wind resource, 750 km transmission line, and a fixed 90% capacity factor, wind+CAES was the most expensive system at ¢6.0/kWh, and did not break even with the next most expensive wind+gas system until p_NGeff=$9.0/GJ. However, under real market conditions, the system with the least dispatch cost (short-run marginal cost) is dispatched first, attaining the highest capacity factor and diminishing the capacity factors of competitors, raising their total cost. We estimate that the wind+CAES system, with a greenhouse gas (GHG) emission rate that is one-fourth of that for natural gas combined cycle plants and about one-tenth of that for pulverized coal plants, has the lowest dispatch cost of the alternatives considered (lower even than for coal power plants) above a GHG emissions price of $35/tC_equiv., with good prospects for realizing a higher capacity factor and a lower total cost of energy than all the competing technologies over a wide range of effective fuel costs. This ability to compete in economic dispatch greatly boosts the market penetration potential of wind energy and suggests a substantial growth opportunity for natural gas in providing baseload power via wind+CAES, even at high natural gas prices.     

Environmental life cycle assessment of alternative fuels for city buses: A case study in Oujda city,Morocco

The road transport sector, particularly public transport, generates significant greenhouse gas emissions due to the excessive use of petroleum-based fuels. The use of alternative fuels with lower environmental impacts is therefore a major challenge to move towards a more sustainable public transport sector. In this context, the current study presents an environmental life cycle assessment of alternative buses, including hybrid (diesel-electricity), electric, and fuel cell buses at a city level in Oujda, Morocco. This study is perfromed according to three main outputs: total energy use by fuel type, GHG emissions, and criteria air pollutants. It is concluded that electric and fuel cell buses represent efficient and sustainable alternatives to public transport during the operational phase and their deployment in Oujda city can potentially offer significant environmental savings in terms of GHG emissions and air pollutants during both the WTT and TTW phases.     

Valuing the greenhouse gas emissions from nuclear power: A critical survey

This article screens 103 lifecycle studies of greenhouse gas-equivalent emissions for nuclear power plants to identify a subset of the most current, original, and transparent studies.     

Transition to hydrogen economy in the United States: A 2006 status report

Energy crises in the latter part of the 20th century, as well as the current increase in the cost of oil, emphasize the need for alternate sources of energy in the United States. Concerns about climate change dictate that the source be clean and not contribute to global warming. Hydrogen has been identified as such a source for many years and the transition to a hydrogen economy was predicted to occur from the mid-1970s to 2000. This paper reports on the status of this transition in the year 2006. Instead of being a clean source of energy, most of the hydrogen produced in the US results from steam reforming of fossil fuels, releasing _CO2${\mathrm{CO}}_2$ and other pollutants to the atmosphere. Nuclear process heat is ideally suited for the production of hydrogen, either using electricity for electrolysis of water, or heat for thermochemical hydrogen production or reforming of fossil fuels. However, no new nuclear plants have been ordered or built in the United States since 1979, and it may be many years before high-temperature nuclear reactors are available for production of hydrogen. Considerable research and development efforts are focused on commercializing hydrogen-powered vehicles to lessen the dependence of the transportation sector on imported oil. However, the use of hydrogen fuel cell vehicles (FCV) in 2006 is two orders-of-magnitude less than what has been predicted. Although it makes little sense environmentally or economically, hydrogen is also used as fuel in internal combustion engines. Development of hydrogen economy will require a strong intervention by external forces.     

Reductions in cost and greenhouse gas emissions with new bulk ship designs enabled by the Panama Canal expansion

Historically, fuel costs have been small compared with the fixed costs of a bulk vessel, its crewing and management. Today, however, fuel accounts for more than 50% of the total costs. In combination with an introduction of stricter energy efficiency requirements for new vessels, this might make design improvement a necessity for all new bulk vessels. This is in contradiction to traditional bulk vessel designs, where the focus has been on maximizing the cargo-carrying capacity at the lowest possible building cost and not on minimizing the energy consumption. Moreover, the Panama Canal has historically been an important design criterion, while the new canal locks from 2014 will significantly increase the maximum size of vessels that can pass. The present paper provides an assessment of cost and emissions as a function of alternative bulk vessel designs with focus on a vessel's beam, length and hull slenderness, expressed by the length displacement ratio for three fuel price scenarios. The result shows that with slenderer hull forms the emissions drop. With today's fuel price of 600 USD per ton of fuel, emissions can thus be reduced by up to 15–25% at a negative abatement cost.     

Greenhouse gas emissions reduction by use of wind and solar energies for hydrogen and electricity production: Economic factors

This study addresses economic aspects of introducing renewable technologies in place of fossil fuel ones to mitigate greenhouse gas emissions. Unlike for traditional fossil fuel technologies, greenhouse gas emissions from renewable technologies are associated mainly with plant construction and the magnitudes are significantly lower. The prospects are shown to be good for producing the environmentally clean fuel hydrogen via water electrolysis driven by renewable energy sources. Nonetheless, the cost of wind- and solar-based electricity is still higher than that of electricity generated in a natural gas power plant. With present costs of wind and solar electricity, it is shown that, when electricity from renewable sources replaces electricity from natural gas, the cost of greenhouse gas emissions abatement is about four times less than if hydrogen from renewable sources replaces hydrogen produced from natural gas. When renewable-based hydrogen is used in a fuel cell vehicle instead of gasoline in a IC engine vehicle, the cost of greenhouse gas emissions reduction approaches the same value as for renewable-based electricity only if the fuel cell vehicle efficiency exceeds significantly (i.e., by about two times) that of an internal combustion vehicle. It is also shown that when 6000 wind turbines (Kenetech KVS-33) with a capacity of 350 kW and a capacity factor of 24% replace a 500-MW gas-fired power plant with an efficiency of 40%, annual greenhouse gas emissions are reduced by 2.3 megatons. The incremental additional annual cost is about $280 million (US). The results provide a useful approach to an optimal strategy for greenhouse gas emissions mitigation.     

A prospective study of bioenergy use in Mexico

Bioenergy is one of the renewable energy sources that can readily replace fossil fuels, while helping to reduce greenhouse gas emissions and promoting sustainable rural development. This paper analyses the feasibility of future scenarios based on moderate and high use of biofuels in the transportation and electricity generation sectors with the aim of determining their possible impact on the Mexican energy system. Similarly, it evaluates the efficient use of biofuels in the residential sector, particularly in the rural sub-sector. In this context, three scenarios are built within a time frame that goes from 2005 to 2030. In the base scenario, fossil fuels are assumed as the dominant source of energy, whereas in the two alternative scenarios moderate and high biofuel penetration diffusion curves are constructed and discussed on the basis of their technical and economical feasibility. Simulation results indicate that the use of ethanol, biodiesel and electricity obtained from primary biomass may account for 16.17% of the total energy consumed in the high scenario for all selected sectors. CO₂ emissions reduction—including the emissions saved from the reduction in the non-sustainable use of fuelwood in the rural residential sector—is equivalent to 87.44 million tons of CO₂ and would account for 17.84% of the CO₂ emitted by electricity supply and transportation sectors when the base case and the high scenario are compared by 2030.