Improving cost-effectiveness for the furnace in a full-scale refinery plant with reuse of waste tail gas fuel

The waste tail gas fuel emitted from refinery plant in Taiwan e.g. catalytic reforming unit, catalytic cracking unit and residue desulfurization unit, was recovered and reused as a replacement fuel. In this study, it was slowly added to the fuel stream of a heater furnace to replace natural gas for powering a full-scale distillation process. The waste tail gas fuel contained on average 60 mol% of hydrogen. On-site experimental results show that both the flame length and orange-yellowish brightness decrease with increasing proportion of waste gas fuel in the original natural gas fuel. Moreover, the adiabatic flame temperature increases as the content of waste gas fuel is increased in the fuel mixture since waste gas fuel has a higher adiabatic flame temperature than that of natural gas. The complete replacement of natural gas by waste gas fuel for a heater furnace operating at 70% loading (i.e. 3.6 × 10⁷ kcal/h of combustion capacity) will save 5.8 × 10⁶ m³ of natural gas consumption, and 3.5 × 10⁴ tons (or 53.4%) of CO₂ emission annually. Recovering and reusing the waste tail gas fuel as natural gas replacement will achieve tremendous savings of natural gas usage and effectively lower the emission of carbon dioxide.     

Enhancing the performance of a high-pressure cogeneration boiler with waste hydrogen-rich fuel

The cogeneration boiler has been applied extensively for simultaneously supplying electrical power and high-pressure steam. In this study, the performance of a high-pressure cogeneration boiler (max 280 tons/h boiler capacity) that burnt fuel oil (FO) and natural gas (NG) in a full-scale petrochemical plant was enhanced by partially replacing the NG with a waste hydrogen-rich refinery gas (RG), a byproduct from catalytic reforming and catalytic cracking operations. The addition of RG does not influence the boiler efficiency; it results in saving the energy consumption and significantly decreasing the greenhouse gas emission. If the inlet FO/NG/RG volumetric flow rate ratio is maintained at 50:33:17, adding RG will save 14,500,000 m³/year of NG and reduce 12,900 tons/year of CO₂ emission. Therefore, the use of RG to partially replace NG has practical benefits for reducing energy consumption and greenhouse gas emission.     

Estimation of the potential for reduced greenhouse gas emission in North-East Russia: A comparison of energy use in mining,mineral processing and residential heating in Kiruna and Kirovsk-Apatity

The energy demand at Murmansk Oblast in North-East Russia is covered at 60% by fossil fuels and at 40% by electricity. This study estimates the potential for reduction of fossil fuel consumption and CO₂-emissions at Murmansk Oblast. The study focus on the municipalities of Apatity and Kirovsk and the apatite ore mining company Apatit JSC . The potential for energy efficiency, reduced fossil fuel consumption and greenhouse gas emissions is estimated by comparison with the of city Kiruna in Northern Sweden, with a climate similar to that of North-East Russia, and with the iron ore mining company LKAB. This study shows that the potential for reduced CO₂-emissions is about 630,700 tons CO₂ annually in the municipalities of Apatity and Kirovsk or 6.3 tons of CO₂ per capita, Apatit JSC not included. These results applied on Murmansk Oblast gives a potential for reduced CO₂-emissions of about 6 Mtons annually in the municipalities together. The specific energy consumption at Apatit JSC is 6–7 times per ton product compared to LKAB. The mining has 4 times higher specific energy consumption per ton raw ore compared to LKAB.     

The energy benefit of stainless steel recycling

The energy used to produce austenitic stainless steel was quantified throughout its entire life cycle for three scenarios: (1) current global operations, (2) 100% recycling, and (3) use of only virgin materials. Data are representative of global average operations in the early 2000s. The primary energy requirements to produce 1 metric ton of austenitic stainless steel (with assumed metals concentrations of 18% Cr, 8% Ni, and 74% Fe) is (1) 53 GJ, (2) 26 GJ, and (3) 79 GJ for each scenario, with CO₂ releases totaling (1) 3.6 metric tons CO₂, (2) 1.6 metric tons CO₂, and (3) 5.3 metric tons CO₂. Thus, the production of 17 million metric tons of austenitic stainless steel in 2004 used approximately 9.0×10¹⁷ J of primary energy and released 61 million metric tons of CO₂. Current recycling operations reduce energy use by 33% (4.4×10¹⁷ J) and CO₂ emissions by 32% (29 million tons). If austenitic stainless steel were to be produced solely from scrap, which is currently not possible on a global level due to limited availability, energy use would be 67% less than virgin-based production and CO₂ emissions would be cut by 70%. The calculation of the total energy is most sensitive to the amount and type of scrap fed into the electric arc furnace, the unit energy of the electric arc furnace, the unit energy of ferrochromium production, and the form of primary nickel.     

Reduction of energy consumption and pollution emissions for industrial furnace using hydrogen-rich tail gas

Using the recovered tail gas (FG) that consists of 60 mol% (50–70 mol%) of hydrogen gas to replace heavy fuel oil (FO) as furnace fuel was studied. With higher FG/FO ratios, the hydrogen content in the fuel increases so that the volume of flue gas reduces to reduce the furnace internal pressure that leads to slower uprising velocity of the thermal flow in the furnace and hence more efficient thermal transmission in the furnace. The results reveal that complete replacement of fuel oil with the recovered tail gas will reduce about 45.8% of the resulting flue gas, lower the furnace radiation zone temperature by 45 °C, raise the furnace convection zone temperature by 18 °C. Additionally, the annual savings of heavy fuel oil can be 2.3 × 10⁴ m³ heavy fuel oil with the reduction of 53.4 tons SO_x emission, 21.9 tons of NO_x emission and 4.9 × 10⁴ tons of CO₂ emission. Therefore, reusing the recovered tail gas to completely replace heavy fuel oil (FO) as the furnace fuel along with operational adjustments of fresh air flow rate and flue baffle angles will alleviate the discharge of greenhouse gas.     

Hydrogen production and CO2 fixation by flue-gas treatment using methane tri-reforming or coke/coal gasification combined with lime carbonation

The production of hydrogen and the fixation of CO₂ can be achieved by treatment of flue gases derived from fossil fuel fired power plants via catalytic methane tri-reforming or by coal gasification in the presence of CaO. A two-step process is designed to be carried out in two reactors: a) a catalytic gasifier or steam-reformer, operating exothermally at 900–1000 K, with inputs of the flue gas, a carbonaceous source, steam and air, as well as CaO from the calciner, and outputs of H₂, and of “spent” CaCO₃ to the calciner; b) a calciner, operating endothermally at 1100–1300 K, with inputs of spent CaCO₃ from the gasifier, make-up fresh CaCO₃, and outputs of CO₂, as well as of CaO, partly recycled to the gasifier and partly processed in a cement plant. Thermochemical equilibrium calculations along with mass/energy balances indicate that for flue-gas treatment by tri-reforming, CO₂ emission avoidance of up to ∼59% and fossil fuel savings of up to ∼75% may be attained when concentrated solar energy is supplied as high-temperature process heat for the calcination step, all relative to conventional H₂ production by coal gasification. If instead fossil fuel would be used to drive the calcination step, the CO₂ emission avoidance and the fuel savings would be only 20% and 67%, respectively. Estimated annual H₂ production from a coal-fired 500 MWe burner by the proposed flue-gas treatment using either CH₄-tri-reforming or coal gasification would amount to 0.7 × 10⁶ or 0.6 × 10⁶ metric tons H₂, respectively. Estimated fossil fuel consumption for H₂ production by tri-reforming or coke gasification would be 149 or 143 GJ fuel/ton H₂.     

Wet and dry cooling systems optimization applied to a modern waste-to-energy cogeneration heat and power plant

In Brescia, Italy, heat is delivered to 70% of 200.000 city inhabitants by means of a district heating system, mainly supplied by a waste to energy plant, utilizing the non recyclable fraction of municipal and industrial solid waste (800,000 tons/year, otherwise landfilled), thus saving annually over 150,000 tons of oil equivalent and over 400,000 tons of CO₂ emissions.     

Improving furnace energy efficiency through adjustment of damper angle

Numerous furnaces and boilers are extensively used in industrial and commercial facilities to generate thermal energy so that small improvements of the furnace thermal efficiency will amount to tremendous reduction of energy consumption and green gas emission. In this research, the furnace flue damper angle is adjusted to lower the pressure in the furnace for reducing the velocity of hot gas rising in the furnace. This allows more time for the heat to be transferred to the thermal flow that improves the furnace overall thermal efficiency. On the other hand, when the damper angle is adjusted from 45 to 39°, the pressure in the furnace rises from −14.7 to −9.3 mmH₂O, the average fuel volumetric flow rate reduces from 751 to 491 m³/h, and the average temperature lowers from 949 to 909 °C in the radiation section and from 756 to 798 °C in the conventional section. Hence, about 1.7 × 10⁶ m³ of fuel gas consumption can be saved, and 1.9 × 10³ ton of CO₂ emission can be reduced annually. The results confirm that simply by adjusting the flue damper angle of a furnace will achieve significant savings of energy and reduction of carbon dioxide emission.     

Reduction of greenhouse gas emission on a medium-pressure boiler using hydrogen-rich fuel control

The increasing emission of greenhouse gases from the combustion of fossil fuel is believed to be responsible for global warming. A study was carried out to probe the influence of replacing fuel gas with hydrogen-rich refinery gas (R.G.) on the reduction of gas emission (CO₂ and NO_x) and energy saving. Test results show that the emission of CO₂ can be reduced by 16.4% annually (or 21,500 tons per year). The NO_x emission can be 8.2% lower, or 75 tons less per year. Furthermore, the use of refinery gas leads to a saving of NT$57 million (approximately US$1.73 million) on fuel costs each year. There are no CO₂, CO, SO_x, unburned hydrocarbon, or particles generated from the combustion of added hydrogen. The hydrogen content in R.G. employed in this study was between 50 and 80 mol%, so the C/H ratio of the feeding fuel was reduced. Therefore, the use of hydrogen-rich fuel has practical benefits for both energy saving and the reduction of greenhouse gas emission.     

Fossil fuels substitution by the solar energy utilization for the hot water production in the heating plant “Cerak” in Belgrade

The main objective of this paper is to evaluate energy and environmental benefits of the large-scale solar heating system connection with district heating system. The assessment of fossil fuels substitution by the solar energy for the hot water production for domestic use, during the summer period, is done. Hot water for district heating and domestic use is produced in heating plant “Cerak” placed in the suburb of Belgrade. The existing production and distribution system are based on fossil fuel energy, mainly on the natural gas. In the first phase of the project plan was to install about 10,000 m² of solar collectors to substitute nearly 25% of natural gas consumption. During the summer period, the saving of natural gas calculated for presented system is approximately 430,000 m³ and in this way 900 t of the CO₂ emissions would be reduced.     

Impact assessment of the increase in fossil fuel prices on the global energy system,with and without CO2 concentration stabilization

It is important to evaluate impacts of fossil fuel price hikes and climate stabilization that force the global energy system to adopt alternative and efficient technologies by routing future energy system dynamics into a different technology roadmap. Hence, a high-regional-resolution and technology-rich DNE21+ model is used for the simulation of some price-hike scenarios for the period from 2000 to 2030 by increasing the ordinate of cost–potential curve of crude oil, natural gas and coal by 55 US$(00)/bbl, 3.8 US$(00)/kcf and 56 US$(00)/tonne, respectively, above their reference values; and 550 ppmv stabilization is implemented by carbon limitation from 6998 to 8250 MtC/yr. This study detected that hike in fossil fuel prices acts as an anti-catalyst for human-induced anthropogenic emissions and alleviates heavy dependency upon fossil fuels. Further, it partially solves problems of climate change by reducing CO₂ emission levels (23%), reflects human behavior through energy conservation (1.4 Gtoe), calls for efficiency improvement (7%), adopts more efficient and alternative technologies, compared to reference; however, with 550 ppmv stabilization, energy conservation rises to 1.6 Gtoe, demands 16% higher efficiency improvement and reduces CO₂ emission by 36%, relative to reference.     

Long-term implications of alternative light-duty vehicle technologies for global greenhouse gas emissions and primary energy demands

This study assesses global light-duty vehicle (LDV) transport in the upcoming century, and the implications of vehicle technology advancement and fuel-switching on greenhouse gas emissions and primary energy demands. Five different vehicle technology scenarios are analyzed with and without a CO₂ emissions mitigation policy using the GCAM integrated assessment model: a reference internal combustion engine vehicle scenario, an advanced internal combustion engine vehicle scenario, and three alternative fuel vehicle scenarios in which all LDVs are switched to natural gas, electricity, or hydrogen by 2050. The emissions mitigation policy is a global CO₂ emissions price pathway that achieves 450 ppmv CO₂ at the end of the century with reference vehicle technologies. The scenarios demonstrate considerable emissions mitigation potential from LDV technology; with and without emissions pricing, global CO₂ concentrations in 2095 are reduced about 10 ppmv by advanced ICEV technologies and natural gas vehicles, and 25 ppmv by electric or hydrogen vehicles. All technological advances in vehicles are important for reducing the oil demands of LDV transport and their corresponding CO₂ emissions. Among advanced and alternative vehicle technologies, electricity- and hydrogen-powered vehicles are especially valuable for reducing whole-system emissions and total primary energy.     

Hydrogen production with CO2 capture by coupling steam reforming of methane and chemical-looping combustion: Use of an iron-based waste product as oxygen carrier burning a PSA tail gas

In this work it is analyzed the performance of an iron waste material as oxygen carrier for a chemical-looping combustion (CLC) system. CLC is a novel combustion technology with the benefit of inherent CO₂ separation that can be used as a source of energy for the methane steam reforming process (SR). The tail gas from the PSA unit is used as fuel in the CLC system.The oxygen carrier behaviour with respect to gas combustion was evaluated in a continuous 500 W_th CLC prototype using a simulated PSA off-gas stream as fuel. Methane or syngas as fuel were also studied for comparison purposes. The oxygen carrier showed enough high oxygen transport capacity and reactivity to fully convert syngas at 880 °C. However, lower conversion of the fuel was observed with methane containing fuels. An estimated solids inventory of 1600 kg MW_th⁻¹ would be necessary to fully convert the PSA off-gas to CO₂ and H₂O. An important positive effect of the oxygen carrier-to-fuel ratio up to 1.5 and the reactor temperature on the combustion efficiency was found.A characterization of the calcined and after-used particles was carried out showing that this iron-based material can be used as oxygen carrier in a CLC plant since particles maintain their properties (reactivity, no agglomeration, high durability, etc.) after more than 111 h of continuous operation.     

CO2 and pollutant emissions from passenger cars in China

In this paper, CO₂ and pollutant emissions of PCs in China from 2000 to 2005 were calculated based on a literature review and measured data. The future trends of PC emissions were also projected under three scenarios to explore the reduction potential of possible policy measures. Estimated baseline emissions of CO, HC, NO_x, PM₁₀ and CO₂ were respectively 3.16×10⁶, 5.14×10⁵, 3.56×10⁵, 0.83×10⁴ and 9.14×10⁷ tons for China’s PCs in 2005 with an uneven distribution among provinces. Under a no improvement (NI) scenario, PC emissions of CO, HC, NO_x, PM₁₀ and CO₂ in 2020 are respectively estimated to be 4.5, 2.5, 2.5, 7.9 and 8.0 times that of 2005. However, emissions other than CO₂ from PCs are estimated to decrease nearly 70% by 2020 compared to NI scenario mainly due to technological improvement linked to the vehicle emissions standards under a recent policy (RP) scenario. Fuel economy (FE) enhancement and the penetration of advanced propulsion/fuel systems could be co-benefit measures to control CO₂ and pollutant emissions for the mid and long terms. Significant variations were found in PC emission inventories between different studies primarily due to uncertainties in activity levels and/or emission factors (EF).     

Experimental study of the energy efficiency of an incinerator for medical waste

The aim of this paper is to explore the flux of usable energy and the coefficient of energy efficiency of an incinerator for medical waste combustion. The incineration facility incorporates a heat recovery system. The installation consists of a loading unit, a combustion chamber, a thermoreactor chamber, and a recovery boiler. The analysis was carried out in the Oncological Hospital in Bydgoszcz (Poland). The primary fuel was comprised of medical waste, with natural gas used as a secondary fuel. The study shows that one can obtain about 660–800 kW of usable energy from 100 kg of medical waste. This amount corresponds to 1000–1200 kg of saturated steam, assuming that the incinerator operates at a heat load above φ > 65%. The average heat flux in additional fuel used for incinerating 100 kg of waste was 415 kW. The coefficient of energy efficiency was set within the range of 47% and 62% depending on the incinerator load. The tests revealed that the flux of usable energy and the coefficient of energy efficiency depend on the incinerator load. In the investigated range of the heat load, this dependence is significant. When the heat load of the incinerator increases, the flux of usable energy and the coefficient of energy efficiency also increase.     

Potential of hydrogen from oil palm biomass as a source of renewable energy worldwide

Various catastrophes related to extreme weather events such as floods, hurricanes, droughts and heat waves occurring on the Earth in the recent times are definitely a clear warning sign from nature questioning our ability to protect the environment and ultimately the Earth itself. Progressive release of greenhouse gases (GHG) such as CO₂ and CH₄ from development of various energy-intensive industries has ultimately caused human civilization to pay its debt. Realizing the urgency of reducing emissions and yet simultaneously catering to needs of industries, researches and scientists conclude that renewable energy is the perfect candidate to fulfill both parties requirement. Renewable energy provides an effective option for the provision of energy services from the technical point of view. In this context, biomass appears as one important renewable source of energy. Biomass has been a major source of energy in the world until before industrialization when fossil fuels become dominant and researches have proven from time to time its viability for large-scale production. Although there has been some successful industrial-scale production of renewable energy from biomass, generally this industry still faces a lot of challenges including the availability of economically viable technology, sophisticated and sustainable natural resources management, and proper market strategies under competitive energy markets. Amidst these challenges, the development and implementation of suitable policies by the local policy-makers is still the single and most important factor that can determine a successful utilization of renewable energy in a particular country. Ultimately, the race to the end line must begin with the proof of biomass ability to sustain in a long run as a sustainable and reliable source of renewable energy. Thus, the aim of this paper is to present the potential availability of oil palm biomass that can be converted to hydrogen (leading candidate positioned as the energy of the millennium) through gasification reaction in supercritical water, as a source of renewable energy to policy-makers. Oil palm topped the ranking as number 1 fruit crops in terms of production for the year 2007 with 36.90 million tonnes produced or 35.90% of the total edible oil in the world. Its potentiality is further enhanced by the fact that oil constitutes only about 10% of the palm production, while the rest 90% is biomass. With a world oil palm biomass production annually of about 184.6 million tons, the maximum theoretical yield of hydrogen potentially produced by oil palm biomass via this method is 2.16×10¹⁰ kg H₂ year⁻¹ with an energy content of 2.59 EJ year⁻¹, meeting almost 50% of the current worldwide hydrogen demand.     

Impacts of CO2 emission constraints on technology selection and energy resources for power generation in Bangladesh

This paper examines the impacts of CO₂ emission reduction target and carbon tax on future technologies selection and energy use in Bangladesh power sector during 2005–2035. The analyses are based on a long-term energy system model of Bangladesh using the MARKAL framework. The analysis shows that Bangladesh will not be able to meet the future energy demand without importing energy. However, alternative policies on CO₂ emission constraints reduce the burden of imported fuel, improve energy security and reduce environmental impacts. The results show that the introduction of the CO₂ emission reduction targets and carbon taxes directly affect the shift of technologies from high carbon content fossil-based to low carbon content fossil-based and clean renewable energy-based technologies compared to the base scenario. With the cumulative CO₂ emission reduction target of 10–20% and carbon tax of 2500 Taka/ton, the cumulative net energy imports during 2005–2035 would be reduced in the range of 39–65% and 37%, respectively, compared to the base scenario emission level. The total primary energy requirement would be reduced in the range of 4.5–22.3% in the CO₂ emission reduction targets and carbon tax 2500 Taka/ton scenarios and the primary energy supply system would be diversified compared to the base scenario.     

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.     

Assessment of Thailand indoor set-point impact on energy consumption and environment

The paper presents an investigation of indoor set-point standard of air-conditioned spaces as a tool to control electrical energy consumption of air-conditioners in Thailand office buildings and to reduce air pollutants. One hundred and forty-seven air-conditioned rooms in 13 buildings nationwide were used as models to analyze the electricity consumption of air-conditioning systems according to their set indoor temperatures, which were below the standard set-point and were accounted into a large scale. Then, the electrical energy and environmental saving potentials in the country were assessed by the assumption that adaptation of indoor set-point temperature is increased up to the standard set-point of 26 °C. It was concluded that the impacts of indoor set-point of air-conditioned rooms, set at 26 °C, on energy saving and on environment are as follows: The overall electricity consumption saving would be 804.60 GWh/year, which would reduce the corresponding GHGs emissions (mainly CO₂) from power plant by 579.31×10³ tons/year.     

Implementation of energy efficiency standards of household refrigerator/freezer in China: Potential environmental and economic impacts

Due to the rapid economic development, living standards in China are improving fast. Chinese families are having more household electrical appliances, among which refrigerators are indispensable. Energy consumption of refrigerators is huge in China and causes environmental concerns. China has issued the national energy efficiency standards of household refrigerators, GB12021.2-2003 and GB12021.2-2008 to promote high-efficiency refrigerator production and use. This study evaluated the impacts of the standards on the environment, manufacturers and consumers over a long-term period of 2003–2023. It first evaluated the potential electricity conservation and GHG emission reduction resulting from energy efficiency improvements driven by the standards. Next, manufacturers’ technological and economic concerns about complying with the standards were discussed. Some efficiency improving design options were considered and the resulting increases in manufacturing cost and retail price were estimated. The return of consumers from invest in efficiency was analyzed based on lifecycle cost saving of the improved models. The economical viability of the standards was then evaluated by national consumer costs and benefits. Results showed that the considered efficiency standards will potentially save a cumulative total of 588–1180 TWh electricity, and reduce emission of 629–1260 million tons of CO₂, 4.00–8.04 million tons of SO_x and 2.37–4.76 million tons of NO_x by 2023, depending on sale share of models by efficiency. In a more environmentally optimal case (75% sale share of high-efficiency models), the national consumer benefits are 121 billion RMB (discounted), with the benefit/cost ratio of consumer’s expenditure being 1.45:1. However, the preference to high-efficiency models is substantial influenced by consumer’s expectation on return from the additional cost on efficiency.