Particulate Matter Reduction Research Articles

Synergistic effects of a carbon emissions trading scheme on carbon emissions and air pollution: The case of China.

Facing the dual pressures of the exacerbation of global climate change and the deterioration of the domestic environment caused by pollution, China has clearly adopted environmental regulatory measures to improve the climate environment. One measure is the carbon emissions trading scheme (CETS), which serves as a notable example of the country's efforts to improve the climate environment. We gathered panel data from 285 prefecture-level cities in China from 2005 to 2018 and used the Difference-in-Differences (DID) model to empirically examine the synergistic effects of the CETS on carbon emissions and air pollution. The results indicate that CETS have been effective in reducing urban carbon emissions by approximately 9.8%. Additionally, the schemes have caused a simultaneous reduction in particulate matter (PM)2.5 emissions by 11.7% and sulfur dioxide (SO2) emissions by approximately 9.7%, mitigating urban air pollution in China. It demonstrates that the scheme has significant synergistic effects on carbon emissions and air pollution. To achieve synergistic effects of CETS, effective measures include reducing energy intensity and upgrading the industrial structure. The implementation of CETS had heterogeneity in different conditions, and the synergistic effect of the scheme is more significant in eastern regions, large cities, and the final industrial stage. Our findings offer innovative solutions for the integrated management of carbon emissions and air pollution and provide valuable insights for policymakers to enhance China's CETS. Integr Environ Assess Manag 2024;20:1112-1124. © 2023 SETAC.

Assessment of the Air Cleaning Performance and Humidity and Temperature Control by Five Evergreen Woody Plants

Indoor air quality (IAQ) directly affects human health. The increase in PM and CO2 concentration indoors caused an increase in the prevalence of sick building syndrome (SBS) symptoms. Plants could contribute to reducing particulate matter (PM) and CO2. This study identifies the most efficient evergreen plant species for improving indoor air quality by assessing the ability of five different indigenous Korean evergreen plant species to reduce PM and CO2 and regulate humidity and temperature under indoor environmental conditions in acrylic chambers. The clean air delivery rates (CADR) were calculated to evaluate the efficacy of plants in reducing PM and CO2. We assessed the performance of removing the five study plants on PM1 (~0.68–3.01 m3/h/leaf area), PM2.5 (~0.73–3.08 m3/h/leaf area), PM10 (~0.67–3.04 m3/h/leaf area), and CO2 (~0.48–1.04 m3/h/leaf area). The species Ilex pedunculosa, Pittosporum tobira, and Gardenia jasminoides were the most effective at reducing PM. The CADR of CO2 also differed among the five plant species and corresponded to their photosynthetic rate. Viburnum odoratissimum var. awabuki, which had the high photosynthetic rate, was most effective at reducing CO2. By contrast, PM reduction was correlated with plant leaf structure. Plants with a high leaf density can accumulate more PM. The plants were also able to control temperature and humidity. The average temperature of the control chamber was higher, and the humidity was lower than that of the plant chambers. In this study, the five evergreen species effectively reduced air pollutants and can be used to improve IAQ.

Restructuring and relocation of polluting industries under air pollution control: Evidence from industrial investment flows between Chinese cities

This paper analyzes the impact of the Air Pollution Prevention and Control Action Plan (APPCAP), an environmental policy for particulate matter reduction implemented in 2013, on the restructuring and relocation of Chinese polluting industries. Based on the paid-in capital of newly registered enterprises, we construct the investment flows at the city-industry level to effectively identify the adjustment of polluting industrial structure and the phenomenon of pollution transfer. We estimate the three-dimensional variations in the investment flows, i.e., time (pre-treatment versus post-treatment), region (more stringent regulations versus more lenient ones), and industry (heavily polluting industries versus lightly polluting ones) with the aid of a difference-in-difference-in-differences (DDD) estimation technique. Our empirical results help to understand the comprehensive impact of command-and-control environmental policy in two ways. For one thing, we find the positive effects of APPCAP in curbing the expansion of polluting industries that would emit smoke and dust in production; for another, our results reveal the latent pollution transfer brought by the differentiated regulation intensity of APPCAP implemented in different regions.

Fine Particulate Matter Reduction through Crop Surface Adsorption in an Agricultural Field Using the Coefficient Derived from Wind Tunnel Experiments

Fine dust can have serious effects on human health and crop growth. Fodder crops can reduce airborne dust by coagulating soil particles and reducing wind speed on the surface and have the effect of reducing fine dust by adsorbing it on the crop surface. In this study, the dust reduction coefficient of crops was derived through a self-manufactured wind tunnel experiment to quantitatively assess the dust reduction effect of crops by type and planting density. Additionally, a dust reduction formula considering crop growth and weather conditions during the cultivation period was derived. The dust reduction coefficient was measured by the gravimetric method and the real-time size distribution of dust concentration before and after the crop. The PM reduction coefficient showed triticale at PM-2.5 82.2 mg/m3, PM-10 120 mg/m3, and barley at PM-2.5 14.5 mg/m3, PM-10 26.9 mg/m3 under moderate planting density. During the general planting density cultivation period of triticale and barley, PM-10 was reduced by 37.8 kg/ha and 8.5 kg/ha, respectively, and PM-2.5 was reduced by 25.9 kg/ha and 4.6 kg/ha. The dust reduction effect during the cultivation period was up to 126.1 kg/ha in terms of PM-10 when triticale was cultivated with densely sowing planting density.

Bioaerosol Sensor for In Situ Measurement: Real-Time Measurement of Bioaerosol Particles in a Real Environment and Demonstration of the Effectiveness of Air Purifiers to Reduce Bioaerosol Particle Concentrations at Hot Spots

In this study, we first conducted laboratory experiments on the sensitivity of a newly developed bioaerosol sensor (BAS) suitable for in situ measurements. Then, we performed an in situ test in a shared student space at a university. Furthermore, the effectiveness of ventilation and air purification as a mitigation measure for a location with high concentrations of bioaerosol particles (hot spots) was verified. The experimental results show that the measured values for polystyrene latex are in good agreement with the predicted Mie theory value. They also show a good response to fluorescent particles. The in situ test showed that the BAS fluorescent system does not respond to non-fluorescent particles but only to fluorescent particles. During respiratory infection outbreaks, real-time detection at hot spots and a reduction in particulate matter, including bioaerosols, through ventilation and air purification equipment are effective. In this study, the BAS measurement results showed significant correlations not only with fluorescent particles but also with live bacteria. This does not prove that viruses can be measured in real time. If real-time measurements for viruses become available in the future, the findings of this study will be helpful in mitigating respiratory tract infections caused by viruses.

Microstructure and Wear Resistance of Fe3Al Coating on Grey Cast Iron Prepared via Direct Energy Deposition

In this study, the potential of Fe3Al coating material as an environmentally friendly alternative to coatings containing critical elements for brake discs was investigated. A buffer layer of Cr–Mo steel (Ferro 55) that was about 500 µm thick was applied on a gray cast iron disc to enhance the coating quality and prevent the formation of hot cracks during solidification. The microstructural analysis of the cross-section of the coating showed that the buffer layer diffused into the Fe3Al coating, forming a combination of Fe3Al, Fe, and Fe3AlC0.5 phases. The tribological properties of the Fe3Al-coated disc were evaluated using pin-on-disc tests against two different copper-free friction materials extracted from commercial brake pads. The wear results show a coefficient of friction comparable to that of an uncoated disc (≈0.55), but with a reduction in particulate matter (PM) emissions, which decreased from 600 to 476 #/cm3. The last issue is an interesting aspect that is gaining increasing importance in view of the upcoming international standards.

Enhancing Sustainability in Urban Transportation with Innovative Mechanical Engineering Solutions for Electric Buses in Jakarta

This study looks into how novel mechanical engineering solutions for electric bus technology in Jakarta could change the industry, with an emphasis on improving sustainability, efficiency, and performance. Quantitative data was gathered through technical inspections, stakeholder questionnaires, and real-time monitoring. According to the results, buses with regenerative braking systems, lightweight construction, and cutting-edge drivetrain technologies consume 15% less energy. A comparative investigation revealed a 12% boost in overall speed and responsiveness and a 20% improvement in braking efficiency. The environmental benefits were highlighted by the environmental impact evaluations, which showed a notable 25% reduction in particulate matter and emissions. Positive responses to surveys conducted among passengers and bus operators demonstrated the practical viability and user pleasure of these advances. Although they recognized the potential, city officials stressed the need for a thorough and gradual implementation strategy. According to the research, creative mechanical engineering solutions might completely transform Jakarta's urban transportation system and serve as a template for effective and sustainable mobility.

Evaluation of PM2.5 and CO2 synergistic emission reduction and its driving factors in China

Chinese government proposed that “reducing pollution while reducing carbon” should be promoted for synergistic emission reduction. It is crucial to evaluate of particulate matter (PM2.5) and carbon dioxide (CO2) synergistic emission reduction level and explore its driving factors in China. Using the coupled coordination model, this study evaluated the synergistic reduction emission levels of PM2.5 and CO2 and studied their spatial agglomeration in China's provinces from 2000 to 2018. The spatiotemporal changes of seven driving factors for synergistic emission reduction were studied using geographic and time weighted regression model. (1) The synergistic emission reduction level showed spatiotemporal differences in China. The level presented a trend of first decreasing and then increasing from 2000 to 2018. It was the lowest in the northern coastal economic zone and the highest in the southern coastal economic zone. It had strong spatial aggregation. The High-High aggregation regions were mainly distributed in the northwest and southwest economic zones. There was only one Low-Low aggregation region. It distributed in the northern coastal economic zone. (2) The energy consumption structure played an important role in promoting synergistic emission reduction, while the industrial structure was a key driving factor that hindered synergistic emission reduction.

Environmental management: a country-level evaluation of atmospheric particulate matter removal by the forests of India.

Particulate matter (PM) is a critical air pollutant, responsible for an array of ailments leading to premature mortality worldwide. Nature-based solutions for mitigation of PM and especially role of forests in mitigating PM from an ecosystem perspective are less explored. Forests provide a natural pollution abatement strategy by providing a surface area for the deposition of PM. Depending on their structure and composition, forests have varying capacities for PM adsorption, which is again less explored. Hence, in the present study, we evaluate the removal capacity of PM by the forest-type groups of India. Deposition flux and total PM removal across sixteen forest types were estimated based on the 2019 dataset of PM using Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) data. Externality values and PM removal costs by industrial equipment were used for associating an economic value to the air pollution abatement service by forests. The total PM2.5 removal by forests in 2019 was estimated to be 1361.28 tons and PM10 was estimated to be 303,658.27 tons. Deposition of PM was found to be high in littoral and swamp forests, tropical semi-evergreen forests, tropical moist deciduous forests, and sub-tropical pine forests. Tropical dry deciduous forests had the highest net weight % removal of PM with 39% removal for PM2.5 and 39% removal for PM10. The air pollution abatement service by forests for PM removal was 188 M US dollars (USD) with externality-based removal service by forests of 2009 M USD. The net PM removed by all forests of India was estimated to be approximately worth ₹ 470-648 Crore (59-81 million dollars) for PM2.5 and worth ₹56,746-1,22,617 Crore (7093-15,327 million dollars) for PM10 based on valuation using value transfer method. The study concludes that forests can be a significant contributor to PM reduction at a global level. Especially for India's National Clean Air Programme and further research and policy considerations, the findings would be extremely useful.

Mutual disposal of municipal solid waste and flue gas on isolated islands

Municipal solid waste (MSW) management in rural and remote areas (e.g., isolated islands) is a noteworthy issue. Transportation of MSW from isolated islands to the mainland requires large-scale energy, so it demands a high amount of diesel fuel in diesel generators. To alleviate environmental pollution and energy consumption during transportation, this paper proposes a mutual disposal strategy for MSW and fuel gas from diesel generators and explores the feasibility and potential benefits based on MSW drying experiment in a self-designed device. The following were the primary conclusions: (1) the flue gas could provide sufficient heat energy for drying MSW, and the effective utilization rate can reach 60.22 ± 2.88%. It would take 60–85 min to dry MSW below 200 °C. (2) Within the permissible limits of environmental standards, the MSW contributes to the reduction of particulate matter and methane in the flue gas, while the carbon monoxide, nitric oxide, and non-methane hydrocarbon contents increase due to thermal decomposition of the MSW. The global warming potential of the carbon in the treated gas can be decreased by 16.94%, and the nitric oxide contributes to carbon emission reduction. (3) The proposed mutual disposal strategy could alleviate issues in landfill leachate and simplify the treatment technology, leading to subsequent environmental, economic, and technical benefits.

Electrostatic precipitator design with wire-cylinder electrodes as a particulate matter reduction

Small <span>industries are inseparable from the production of gaseous pollutants. One of the contents of exhaust gases produced from small industrial activities is particulate matter. The consequences of exposure to particulate matter for too long are coughing, cancer, blood coagulation, and death. For this reason, a tool is needed to capture particulate matter in small industrial exhaust gases. Based on the problems described, this research proposes using the electrostatic precipitator with the cockroft-walton method because this method is very effective in capturing particulate matter. The research results on electrostatic precipitator (ESP) with a pair of electrodes will achieve an efficiency of 25.4% when the voltage regulator is 20 V, while the efficiency is 98.7% when the voltage regulator is 35 V. The ESP with two pairs of electrodes will achieve 99.5% efficiency when the voltage regulator is 30 volts. Installing a vibrator as a particle thresher at the electrode is unsuitable for low-temperature exhaust gases because it produces a liquid and sticky residue that makes it difficult to fall off.</span>

Experimental investigation of ternary biodiesel blends combustion in a diesel engine to reduce emissions

The study presents an experimental investigation of two new ternary biodiesel blends, namely, ManCr_Pa (a mixture of Mandarin, Crambe biodiesel and paraffin as an additive) and AvBn_Pa (mix of Avocado, Bush nut biodiesel and paraffin) by modifying the critical fuel properties closer to the diesel fuel. Those ternary blends' performance, emission and combustion characteristics were compared with diesel and typical B5 blends at the same engine conditions. The result reveals that at high engine rpm, the new ternary biodiesel blends exhibited nearly similar engine performance to that of diesel fuel with a significant reduction of carbon monoxide (33.3%), hydrocarbons (33.3 to 73.3%) and particulate matter (17.8 to 28.8%). For instance, brake power (BP), brake mean effective pressure (BMEP), and brake thermal efficiency (BTE) slightly decreased by 0.25 to 0.38, 0.27 to 0.42 and 0.04%, respectively, whereas brake specific fuel consumption (BSFC) slightly increased by 0.52%. The ternary blends also demonstrated closer combustion behaviour, i.e. heat release rate (HRR) with diesel at full load conditions. Compared with the typical B5 blend, the modified ternary biodiesel blends showed better engine performance with a substantial reduction of emissions. Interestingly, the ternary blends exhibited lower NOx emissions than the B5 blend. The study concluded that the newly developed ternary biodiesel blends are superior to ordinary B5 blends and closely performing fuel to standard diesel. The results of this study have important implications for using these new blends as substitutes for diesel while realising similar benefits.

Bedding Management for Suppressing Particulate Matter in Cage-Free Hen Houses

Cage-free (CF) layer houses tend to have high particulate matter (PM) levels because of bedding/litter floor and the birds’ activities, such as perching, dustbathing, and foraging on it. It has been reported that optimizing bedding management can potentially suppress PM levels in CF houses. The objectives of this study were to (1) test the effect of the top application of new bedding materials (BMs) on PM levels and (2) compare different BM PM reduction efficiencies. Small flake shavings (SFS), large flake shavings (LFS), and aspen wood chips (AWC) were top-dressed on the surface of the original litter (33-week-old litter) evenly in each of the BM treatment rooms at 20% volume of the original litter floor. The initial litter depths in the control, SFS, LFS, and AWC rooms were 4.6 ± 0.6, 4.8 ± 0.8 cm, 4.8 ± 0.8 cm, and 4.6 ± 0.9 cm, respectively. One room was used as a control without adding new BM. The results indicate that the top application of new bedding suppressed PM levels in all treatment rooms (p < 0.01). The PM2.5 reductions in the SFS, AWC, and LFS treatment rooms were 36.5%, 34.6%, and 28.9% greater than in the control room, respectively. The mitigation efficiencies were different between PM sizes. For instance, PM2.5, PM10, and TSP in the SFS room were lower than in the control room by 36.5%, 39.4%, and 38.7%, respectively. For litter quality, the moisture content was 18.0 ± 2.8, 20.0 ± 3.1, 20.6 ± 2.4, and 19.7 ± 4.2% in the control, SFS, LFS, and AWC rooms, respectively. Treatment rooms with 20% new BM had 10% higher litter moisture than the control room. The findings of this study reveal that the top application of new bedding on old litter is a potential strategy for reducing PM generation in CF houses. Further studies are warranted, such as regarding the effect of different ratios of new bedding on PM reduction, cost analysis, and verification tests in commercial CF houses.

Evaluation of Particulate Matter (PM2.5) Reduction through Greenwalls in Classrooms

Evaluation of Particulate Matter (PM_2.5) Reduction through Greenwalls in Classrooms

Effect of hydrogen and methane in dual fuel mode in light diesel engine by VIS and IR imaging

Energy transition strongly leads researcher to find short-term alternative carbon-free fuels to be used in internal combustion engines. An interesting and transient solution can be the dual fuel (DF) technology. It can offer significant reduction of carbon dioxide and pollutant emissions. In this paper, DF operation was performed in an optically accessed research diesel engine running at a constant speed of 1500 rpm. Substitute fuels (methane or hydrogen) were injected in the intake manifold in front of the entrance of the tumble intake port. The objective was to compare the two DF modes using simultaneously Fast UV–Visible and Fast Infrared (IR) Imaging. We observed that IR camera was able to give deeper combustion information and allowed to grab the whole phenomenon for both DF hydrogen and methane, while identifying the combustion starting points. Also, IR acquisitions for premixed hydrogen evidenced an unpredictably behaviour of the mixture, demonstrating the necessity of a specific Diesel injection strategy to avoid hydrogen auto-ignition at higher engine load. Finally, a comparison of the measured emissions at the exhaust evidenced that in DF mode (both with CH4 and H2) a significant reduction of particulate matter is achieved with respect to conventional diesel operation. In addition, when hydrogen is used as primary fuel, a more efficient combustion is obtained drastically reducing HC and CO2.

Improvement of the reduction of condensable particulate matter in flue gas scrubbing process

Condensable particulate matter (CPM) is characterized by complex composition, non-negligible emission concentration, and fine or ultrafine in size after conversion to particles, which is difficult to remove. Current methods to control CPM are not fully developed and mainly focus on synergistic removal of CPM in existing air pollution control devices, such as CPM reduction through scrubbing processes in wet flue gas desulfurization (WFGD) systems. In this work, an experimental system including a simulated WFGD scrubber, also referred to as the primary scrubber (PS), and a secondary scrubber (SS) was built to explore measures to improve the CPM reduction performance during scrubbing. The operating parameters of the liquid-to-gas (L/G) ratio and the spray temperature in the two scrubbers were tuned in the experiments. The results indicated that CPM could be reduced in the PS by conversion to filterable particulate matter (FPM), and captured by the spray droplets through the effects of dissolution and condensation, but the reduction was not very efficient. In the SS, the reduction performance of CPM could be further improved due to increased dissolution of CPM caused by increased opportunities for gas-liquid contact, and increased condensation of CPM due to lower spray temperature. The FPM transformed from the CPM in the PS could also be reduced in the SS by the effects of diffusiophoresis and thermophoresis contributed by water vapor condensation. An increase in the L/G ratio could improve the CPM reduction.

Synergistic promotion of particulate matter reduction and production performance via adjusting electrochemical reactions in the zinc electrolysis industry

Heavy particulate matter (PM) pollution and high energy consumption are the bottlenecks of hydrometallurgy, especially in the electrolysis process. Therefore, an urgent need is to explore PM reduction methods with production performance co-benefits. This study presents three PM reduction methods based on controlling operating parameters, i.e., lowering electrolyte temperature, H2SO4 concentration, and current density of the cathode. The optimized conditions were also investigated using the response surface methodology to balance the PM reduction effect and Zn production. The results showed that lowering electrolyte temperature is the most efficient, with an 89.0% reduction in the PM generation flux (GFPM). Reducing H2SO4 concentration led to the minimum side effects on the current efficiency of Zn deposition (CEZn) or power consumption (PC). With the premise of non-deteriorating CEZn and PC, GFPM can be reduced by 86.3% at the optimal condition (electrolyte temperature = 295 K, H2SO4 = 110 g/L, current density = 373 A/m2). In addition, the reduction mechanism was elucidated by comprehensively analyzing bubble characteristics, electrochemical reactions, and surface tension. Results showed that lower electrolyte temperature inhibited the oxygen evolution reaction (OER) and compressed gas volume. Lower H2SO4 concentration inhibited the hydrogen evolution reaction (HER) and reduced electrolyte surface tension. Lower current density inhibited both OER and HER by decreasing the reaction current. The inhibited gas evolutions reduced the microbubbles’ number and size, thereby reducing GFPM. These results may provide energy-efficient PM reduction methods and theoretical hints of exploring cleaner PM reduction approaches for industrial electrolysis.

Assessment of COVID-19 lockdown impact on PM10 and PM2.5 concentrations in the Mexico City Metropolitan Area

PM10 and PM2.5 concentrations are regularly monitored because they cause adverse effects on human health. The concentrations of PM10 and PM2.5 vary within a city due to land use, the amount of traffic, and pollution sources. As the COVID-19 pandemic spread around the world, lockdowns were enacted to stop the spread of the virus. These lockdowns meant reduced mobility and the halt of certain economic activities which had an impact on air pollution sources. In this paper, we assess the effect of the lockdown enacted in April-May 2020 in the Mexico City Metropolitan Area on PM10 and PM2.5 concentrations, using statistical analysis tools. MODIS-derived aerosol optical depth is used to assess the change of aerosols spatial distribution during the lockdown. Furthermore, a Mann-Whitney test is applied to PM10 and PM2.5 data from ground-based monitoring stations to evaluate the effects of lockdown. A general reduction of 20 % of PM10 and 10 % in PM2.5 was found. Overall, a 15 % reduction in particulate matter was found in Mexico City due to lockdown.

Relationships between ozone and particles during air pollution episodes in arid continental climate

For human health, tropospheric ozone (O3), particles (PM2.5 and PM10, particles with aerodynamic diameter <2.5 and 10 μm), and nitrogen dioxide (NO2) are the most harmful air pollutants. We have investigated the simultaneity of PM2.5, PM10, NO2, and O3 occurrence by using data from 21 ground-based monitoring stations in a megacity of the Middle East, Tehran (Iran), between 2011 and 2022. In Tehran, the daily PM2.5 (21–45 μg m−3), PM10 (52–108 μg m−3) and NO2 (75–146 μg m−3) mean concentrations have largely exceeded the 24-h limit value established by the 2021 World Health Organization for the protection of human health, i.e., 15, 45 and 25 μg m−3, respectively, in particular for NO2. The ground-level daily O3 concentrations ranged from 26 to 47 μg m−3. Changes in aerosols burden (e.g., PM2.5 and PM10) affect surface O3 through changes in aerosol chemistry and photolysis rates. Following the dust events and for the days with PM2.5 and PM10 exceeding 50 and 100 μg m−3, respectively, we observed a reduction of surface O3 levels (- 30.0% and - 13.5%), concurrently to surface NO2 (+27.9% and +16.6%) levels increases compared to the non-dusty clear-sky days over Tehran city. Surface O3 formation is suppressed under high particulate matter (PM) levels in the atmosphere, in particular PM2.5, likely due to weakened photochemical reactions (lower solar radiation and air temperature), dilution effect, and heterogeneous chemical processes occurring onto the PM2.5 surface (reactive uptake of nitrogen oxides, NOx, and hydrogen oxide radicals, HOx). To achieve O3-PM co-improvement in cities, we recommend reductions in NOx emissions concurrently with significant reductions in PM and Volatile Organic Compounds emissions, for instance by suitable greening and re-naturing programs.

Evaluation of the Power Generation Impact for the Mobility of Battery Electric Vehicles

European institutions have decided to ban the sale of Internal Combustion Vehicles (ICEVs) in the EU from 2035. This opens a possible scenario in which, in the not-too-distant future, all vehicles circulating in Europe are likely to be Battery Electric Vehicles (BEVs). The Spanish vehicle fleet is one of the oldest and has the lowest percentage of BEVs in Europe. The aim of this study is to evaluate the hypothetical scenario in which the current mobility of ICEVs is transformed into BEVs, in the geographical area of the province of Barcelona and in Spain in general. The daily electricity consumption, the required installation capacity of wind and solar photovoltaic energies, and the potential reduction of NOx and particulate matter (PM) emissions are estimated. The daily emission reduction would be about 314 tons of NOx and 17 tons of PM in Spain. However, the estimated investment required in Spain to generate the additional electricity from renewable sources would be enormous (over EUR 25.4 billion), representing, for example, 5.5% of the total national budget in 2022.