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Costs and Benefits of Afforestation with Renewable Electricity Based Desalination: Case Study for Egypt
... In Egypt, as well as other sunbelt countries facing high levels of water stress and prolonged droughts, BECCS is not a viable option due to the large water demand for the growth of biomass [38]. However, desalination-based afforestation [124,125] offers a window of opportunity for such countries to deploy a biomass-based route as part of their CDR portfolio [35]. The viability of this solution depends on several factors including the LCOE, the levelised cost of water of seawater desalination plants and land availability, among others. ...
... Caldera et al. [124] investigated the costs and benefits of using REbased seawater desalination plants to irrigate forests on the suitable land areas of Egypt. A mix of trees suitable for growth in arid environments were modelled on bare and restoration land of Egypt for the period from 2030 to 2100. ...
... The land use of existing DAC units is estimated to be 0.4 km 2 per Mt of CO 2 sequestered. In contrast, Caldera et al. [124] find that for the case of Egypt, afforestation with RE-based desalination requires about 370 km 2 /MtCO 2 , out of which 12 km 2 /MtCO 2 is for the energy system by mid-century and decreases to about 193 km 2 /MtCO 2 by 2100. The total afforestation area in Egypt is estimated to be about 16% of the country's total area. ...
Transitioning to 100% renewable energy to mitigate climate change requires solutions for hard-to-abate energy sectors. It must also be complemented with negative emissions technologies to ensure climate security. Previous studies have investigated the feasibility of e-fuels and e-chemicals production for export and some carbon dioxide removal technologies in several regions. This study investigates, for the first time, the techno-economic impacts of offering such services on an exporting country's energy system as it transitions to 100% renewable energy by 2050. Egypt is used as a representative case study for sunbelt countries with adequate land area. Four scenarios with different system configurations have been investigated using the LUT Energy System Transition Model and compared to a reference 100% domestic renewable energy system. The results show that Egypt can technically provide 5% of the required global carbon dioxide removal capacity starting from 2035, and 10% of Europe's demand for e-fuels and e-chemicals starting from 2025 within land use constraints. The provision of both services enhances the domestic energy system performance by reducing the levelised costs of important feedstocks, carbon dioxide and hydrogen, as well as other domestic cost metrics and system losses. These findings are extendable and relevant to similar sunbelt countries. They are also relevant to European countries looking to fulfil their climate targets while diversify their energy imports sources. Overall, this study is an important step in 100% renewable energy transition research and international climate change mitigation efforts.
Flexibility options are essential components in highly renewable energy systems due to the inherent variability of renewable energy sources, such as solar photovoltaics and wind power. The adoption of renewable energy aligns with the United Nations Sustainable Development Goal 7, ensuring access to affordable, reliable, sustainable, and modern energy for all. This study investigates the impact of flexibility alternatives within the framework of 100% renewable energy systems through a systematic literature review to identify energy system analyses of at least 95% renewable energy supply for at least one sector in at least one scenario. 1067 articles from 1975 to 2023 were analysed to understand the functionality of flexibility options in highly renewable energy systems. The identified flexibility options include power-to-X, energy storage, demand response, power grids, and curtailment. The results indicate that within the field of 100% renewable energy systems, electricity-based solutions have emerged as the default. Various electricity-based fuels are used, with e-hydrogen and e-methane being the most widely discussed in 46% and 19% of articles, followed by Fischer-Tropsch and e-methanol with 3% of studies, respectively. Battery storage is covered by 60% of articles, followed by e-fuels options, and pumped hydro energy storage. Demand response was identified as the least included method. 46% of the articles highlight the role of transmission grids and 25% include curtailment. Early 100% renewable energy system analyses focused on flexibility in the power sector, whereas the shift of studies to a Power-to-X Economy has broadened research to flexibility options across the entire energy-industry system.
Carbon dioxide removal (CDR) is essential to achieve ambitious climate goals limiting global warming to less than 1.5°C, and likely for achieving the 1.5°C target. This study addresses the need for diverse CDR portfolios and introduces the LUT-CDR tool, which assesses CDR technology portfolios aligned with hypothetical societal preferences. Six scenarios are described, considering global deployment limitations, techno-economic factors, area requirements, technology readiness, and storage security for various CDR options. The results suggest the feasibility of large-scale CDR, potentially removing 500-1750 GtCO2 by 2100 to meet the set climate targets. For a 1.0°C climate goal, CDR portfolios necessitate 12.0-37.5% more primary energy compared to a scenario without CDR. Remarkably, funding a 1.0°C target requires only 0.42-0.65% of the projected global gross domestic product. Bioenergy carbon capture and sequestration and rainfall-based afforestation play limited roles, while secure sequestration of captured CO2 via direct air capture, electricity-based carbon sequestration, and desalination-based afforestation emerge as more promising options. The study offers crucial techno-economic parameters for implementing CDR options in future energy-industry-CDR system analyses and demonstrates the tool's flexibility through alternative assumptions. It also discusses limitations, sensitivities, potential trade-offs, and outlines options for future research in the area of large-scale CDR.
Ecosystem restoration is a critical nature-based solution to mitigate climate change. However, the carbon sequestration potential of restoration, defined as the maximum achievable carbon storage, has likely been overestimated because previous studies have not adequately accounted for the competition between ecosystem water demands for maximizing carbon sequestration and human water needs. Here we used a comprehensive process-based model combined with extensive land-use data and evaporation recycling accounting for land–atmosphere feedback to estimate the water requirements associated with ecosystem restoration. We found that achieving the carbon sequestration potential of restoration would significantly reduce global water availability per capita by 26%, posing considerable risks to water security in water-stressed and highly populated regions. If human water use is safeguarded, the achievable carbon sequestration potential would be reduced by a third (from 396 PgC to 270 PgC). Brazil, the United States and Russia have the largest achievable potentials. Future projections accounting for changes in climate, atmospheric CO2, land use and human population under the shared socioeconomic pathway (SSP) scenarios SSP119, SSP245 and SSP585 suggest an increase in this achievable potential to 274–302 PgC by the end of the century, with China expected to have the largest potential. Our findings provide a nuanced understanding of the trade-offs and synergies between carbon sequestration goals and water security, offering an empirical framework to guide the sustainable implementation of ecosystem restoration strategies.
This paper introduces a visionary strategy, Rebalancing Regional and Remote Australia. It aims at transforming Australia into a significant global carbon sink by sequestering 4 gigatonne (Gt) of CO2 equivalent annually, leveraging about 25% of the nation’s land area. Addressing the unique challenges of Australia’s arid climate, the plan employs innovative, proven solutions in energy, water, and agriculture, including agrivoltaics, to enhance sustainability across diverse environmental and socioeconomic contexts. A central pillar of the plan is the creation of sustainable regional and remote communities. Designed for scalability, it begins with a pilot community of 100 000 residents, showcasing the initiative’s feasibility and potential for significant return on investment. Beyond its environmental objectives, the plan presents substantial business opportunities, positioning Australia as a leader in global sustainability efforts. Through collaborative innovation, it offers a model for national and international action, highlighting the imperative for comprehensive strategies that promote economic, environmental, and social advancement.
Twenty-five years since foundational publications on valuing ecosystem services for human well-being1,2, addressing the global biodiversity crisis³ still implies confronting barriers to incorporating nature’s diverse values into decision-making. These barriers include powerful interests supported by current norms and legal rules such as property rights, which determine whose values and which values of nature are acted on. A better understanding of how and why nature is (under)valued is more urgent than ever⁴. Notwithstanding agreements to incorporate nature’s values into actions, including the Kunming-Montreal Global Biodiversity Framework (GBF)⁵ and the UN Sustainable Development Goals⁶, predominant environmental and development policies still prioritize a subset of values, particularly those linked to markets, and ignore other ways people relate to and benefit from nature⁷. Arguably, a ‘values crisis’ underpins the intertwined crises of biodiversity loss and climate change⁸, pandemic emergence⁹ and socio-environmental injustices¹⁰. On the basis of more than 50,000 scientific publications, policy documents and Indigenous and local knowledge sources, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) assessed knowledge on nature’s diverse values and valuation methods to gain insights into their role in policymaking and fuller integration into decisions7,11. Applying this evidence, combinations of values-centred approaches are proposed to improve valuation and address barriers to uptake, ultimately leveraging transformative changes towards more just (that is, fair treatment of people and nature, including inter- and intragenerational equity) and sustainable futures.
The Intergovernmental Panel on Climate Change concludes that climate change has already caused substantial damages at the current 1.2°C of global warming and that warming of 1.5°C would elevate risks of a wide-range of climate tipping points. For example, wet-bulb temperatures are already exceeding safe levels, and the melting of the Greenland and West Antartic ice sheets would lead to over ten metres of sea level rise, representing an existential threat to coastal cities, low-lying nation states, and human wellbeing worldwide. We call for a broad scientific discussion about a stricter and more ambitious climate target of 1.0°C by the end of this century. Comprehensive electrification and highly renewable energy systems offer a pathway to sub-1.5°C futures through rapid defossilisation and large-scale, electricity-based carbon dioxide removal. Independent scenarios show that restoring a stable and safe climate is attainable with coordinated policy and economic support.
The stability and resilience of the Earth system and human well-being are inseparably linked1–3, yet their interdependencies are generally under-recognized; consequently, they are often treated independently4,5. Here, we use modelling and literature assessment to quantify safe and just Earth system boundaries (ESBs) for climate, the biosphere, water and nutrient cycles, and aerosols at global and subglobal scales. We propose ESBs for maintaining the resilience and stability of the Earth system (safe ESBs) and minimizing exposure to significant harm to humans from Earth system change (a necessary but not sufficient condition for justice)⁴. The stricter of the safe or just boundaries sets the integrated safe and just ESB. Our findings show that justice considerations constrain the integrated ESBs more than safety considerations for climate and atmospheric aerosol loading. Seven of eight globally quantified safe and just ESBs and at least two regional safe and just ESBs in over half of global land area are already exceeded. We propose that our assessment provides a quantitative foundation for safeguarding the global commons for all people now and into the future.
Transitioning to 100% renewable energy to mitigate climate change requires solutions for hard-to-abate energy sectors. It must also be complemented with negative emissions technologies to ensure climate security. Previous studies have investigated the feasibility of e-fuels and e-chemicals production for export and some carbon dioxide removal technologies in several regions. This study investigates, for the first time, the techno-economic impacts of offering such services on an exporting country's energy system as it transitions to 100% renewable energy by 2050. Egypt is used as a representative case study for sunbelt countries with adequate land area. Four scenarios with different system configurations have been investigated using the LUT Energy System Transition Model and compared to a reference 100% domestic renewable energy system. The results show that Egypt can technically provide 5% of the required global carbon dioxide removal capacity starting from 2035, and 10% of Europe's demand for e-fuels and e-chemicals starting from 2025 within land use constraints. The provision of both services enhances the domestic energy system performance by reducing the levelised costs of important feedstocks, carbon dioxide and hydrogen, as well as other domestic cost metrics and system losses. These findings are extendable and relevant to similar sunbelt countries. They are also relevant to European countries looking to fulfil their climate targets while diversify their energy imports sources. Overall, this study is an important step in 100% renewable energy transition research and international climate change mitigation efforts.
The Paris Agreement targets to halt the progression of climate change necessitate global cooperation and renewable energy uptake in developed and developing countries at similar rates. This study explores the energy transition pathway options for Egypt across the power, heat, transport, and desalination sectors as a representative case study for other emerging sunbelt economies. The LUT Energy System Transition Model has been used to investigate the feasibility of six scenarios, including four variations of best policy, delayed policy, and current policy scenarios. The least-cost solution, achieving 100% renewable energy and zero CO2 emissions by 2050, is dominated by solar photovoltaics at 90% of the total primary energy demand. Key transition enablers are the excellent and low-cost solar resources, energy storage, and Power-to-X technologies allowing high electrification and full sector coupling. The results reveal that the current and delayed policy scenarios are the most expensive pathways, highlighting the value of leapfrogging into a fully renewable system. Such a transition would require policy reforms that balance investment risks in emerging economies and enable its financial mobilisation. The structural results of this study provide a reliable guide for energy transition planning in Egypt as well as other emerging sunbelt economies.
Energy systems research requires a variety of demand scenarios for possible futures. Comprehensive energy demand modelling is often made with a simplified approach or based on assumptions scattered among various sources, if it is published at all. There is no detailed discussion of the impact of various macro-economic scenarios on different levels of energy demand available. This study uses LUT-DEMAND, a novel modelling tool for energy demand, to create comprehensive demand input data in high spatial resolution globally and high temporal resolution until 2100. A multi-step approach is applied to estimate the energy demand. A variety of economic and demographic scenarios are explored, including the shared socio-economic pathways. The total primary energy demand is estimated for possible limitations caused by the overall energy demand and chosen technologies. The results for this century's energy supply for ambitious transition targets are presented, and they show a significant impact of macro-economic assumptions on scale and trajectory on all levels of energy demand. Among the explored scenarios, the total primary energy demand may rise to 399 PWh (1435 EJ) by 2100, with a maximum estimated solar photovoltaic capacity demand of about 200 TWp. LUT-DEMAND and its documentation are available in an open-access online repository.
Afforestation is one of the most practised carbon dioxide removal methods but is constrained by the availability of suitable land and sufficient water resources. In this research, existing concepts of low-cost renewable electricity (RE) and seawater desalination are built upon to identify the global CO2 sequestration potential if RE-powered desalination plants were used to irrigate forests on arid land over the period 2030–2100. Results indicate a cumulative CO2 sequestration potential of 730 GtCO2 during the period. Global average cost is estimated to be €457 per tCO2 in 2030 but decrease to €100 per tCO2 by 2100, driven by the decreasing cost of RE and increasing CO2 sequestration rates of the forests. Regions closer to the coast with abundant solar resources and cooler climate experience the least costs, with costs as low as €50 per tCO2 by 2070. The results suggest a key role for afforestation projects irrigated with RE-based desalination within the climate change mitigation portfolio, which is currently based on bioenergy carbon capture and storage, and direct air carbon capture and storage plants.
Societal Impact Statement
Mixed species plantings present an attractive alternative to monoculture reforestation through their added benefits to biodiversity. Yet there is ambiguity in the use of the term ‘biodiversity’ in carbon and biodiversity markets, which may create perverse outcomes when designing schemes and projects. Here, we review how the concept of biodiversity is defined and applied in reforestation projects, and restoration more broadly. Improved transparency around the use of the term biodiversity is urgently needed to provide rigour in emerging market mechanisms, which seek to benefit the environment and people.
Summary
Reforestation to capture and store atmospheric carbon is increasingly championed as a climate change mitigation policy response. Reforestation plantings have the potential to provide conservation co‐benefits when diverse mixtures of native species are planted, and there are growing attempts to monetise biodiversity benefits from carbon reforestation projects, particularly within emerging carbon markets. But what is meant by ‘biodiverse’ across different stakeholders and groups implementing and overseeing these projects and how do these perceptions compare with long‐standing scientific definitions? Here, we discuss approaches to, and definitions of, biodiversity in the context of reforestation for carbon sequestration. Our aim is to review how the concept of biodiversity is defined and applied among stakeholders (e.g., governments, carbon certifiers and farmers) and rights holders (i.e., First Nations people) engaging in reforestation, and to identify best‐practice methods for restoring biodiversity in these projects. We find that some stakeholders have a vague understanding of diversity across varying levels of biological organisation (genes to ecosystems). While most understand that biodiversity underpins ecosystem functions and services, many stakeholders may not appreciate the difficulties of restoring biodiversity akin to reference ecosystems. Consequently, biodiversity goals are rarely explicit, and project goals may never be achieved because the levels of restored biodiversity are inadequate to support functional ecosystems and desired ecosystem services. We suggest there is significant value in integrating biodiversity objectives into reforestation projects and setting specific restoration goals with transparent reporting outcomes will pave the way for ensuring reforestation projects have meaningful outcomes for biodiversity, and legitimate incentive payments for biodiversity and natural capital accounting.
Research on 100% renewable energy systems is a relatively recent phenomenon. It was initiated in the mid-1970s, catalyzed by skyrocketing oil prices. Since the mid-2000s, it has quickly evolved into a prominent research field encompassing an expansive and growing number of research groups and organizations across the world. The main conclusion of most of these studies is that 100% renewables is feasible worldwide at low cost. Advanced concepts and methods now enable the field to chart realistic as well as cost- or resource-optimized and efficient transition pathways to a future without the use of fossil fuels. Such proposed pathways in turn, have helped spur 100% renewable energy policy targets and actions, leading to more research. In most transition pathways, solar energy and wind power increasingly emerge as the central pillars of a sustainable energy system combined with energy efficiency measures. Cost-optimization modeling and greater resource availability tend to lead to higher solar photovoltaic shares, while emphasis on energy supply diversification tends to point to higher wind power contributions. Recent research has focused on the challenges and opportunities regarding grid congestion, energy storage, sector coupling, electrification of transport and industry implying power-to-X and hydrogen-to-X, and the inclusion of natural and technical carbon dioxide removal (CDR) approaches. The result is a holistic vision of the transition towards a net-negative greenhouse gas emissions economy that can limit global warming to 1.5°C with a clearly defined carbon budget in a sustainable and cost-effective manner based on 100% renewable energy-industry-CDR systems. Initially, the field encountered very strong skepticism. Therefore, this paper also includes a response to major critiques against 100% renewable energy systems, and also discusses the institutional inertia that hampers adoption by the International Energy Agency and the Intergovernmental Panel on Climate Change, as well as possible negative connections to community acceptance and energy justice. We conclude by discussing how this emergent research field can further progress to the benefit of society.
The environmental threat of discharging highly saline desalination brine into the sea and an expected growth in global demand for raw materials have increased interest in the idea of integrating desalination and material extraction. This paper examines the material extraction potential of desalination brines corresponding to the seawater desalination volume required to meet the projected global demand for freshwater. The results show that a growing use of seawater desalination techniques to solve the upcoming high water stress provides an increased material extraction potential by 2050, particularly for highly concentrated materials. For example, in the studied scenario, the extraction potential for magnesium and lithium in 2050 is approximately 2243 and 3.1 times the corresponding 2018 production, respectively. The analysis shows that the estimated lithium potential may be sufficient to ameliorate the expected shortage over this century, while the magnesium potential can significantly exceed the future demand. Several seawater materials with low concentrations do not have adequate 2050 extraction potential to be considered a viable resource even compared to present production. This study shows that the promising resource potential of desalination brines for elements such as lithium requires development of suitable extraction techniques that overcome the identified techno-economic challenges.
Egypt has a significant role in the international energy transit being one of the major economies in the African continent, however its energy sector is still overwhelmed with the local energy demands. It has been predicted that Egypt's CO2 emissions could increase by around 125%, over the period from 2012 to 2035, if the nation's energy demand is met using conventional power generation technologies. Given that Egypt has signed the Kyoto protocol and has recognised the role of international cooperation in facing climate change, the country should focus on meeting the growing energy demand using clean energy technologies. In the meantime, Egypt has been facing many challenges due to the water scarcity issues and the environmental risks arising from the lack of efficient solid waste management strategies over the last few decades. It has been predicted that country's crude oil reserves might be depleted within the next 15 y or so. To face these challenges effectively and also to enforce the Egyptian role in international energy transit, renewable energy (RE) technologies and their applications should be the main focus of the current/future Egyptian energy frameworks. This review summarises the current energy outlook of Egypt while analysing the country's potential in harnessing energy from sustainable sources. In general, it has been found that Egypt's renewable energy sector is yet to be exploited for sustainable energy production through its diverse and plentiful resources. Eventually, two scenarios have been proposed to consider in achieving the nation's 2035 energy target which is to generate 42% of the country's energy need through renewable sources. This study should help Egypt and other countries to set the way forward in achieving the NET ZERO target that the whole world is aiming to fulfil over the next few decades.
The rapid deployment of large numbers of utility-scale photovoltaic (PV) plants in the United States, combined with heightened expectations of future deployment, has raised concerns about land requirements and associated land-use impacts. Yet our understanding of the land requirements of utility-scale PV plants is outdated and depends in large part on a study published nearly a decade ago, while the utility-scale sector was still young. We provide updated estimates of utility-scale PVs power and energy densities based on empirical analysis of more than 90% of all utility-scale PV plants built in the United States through 2019. We use ArcGIS to draw polygons around satellite imagery of each plant within our sample and to calculate the area occupied by each polygon. When combined with plant metadata, these polygon areas allow us to calculate power (MW/acre) and energy (MWh/acre) density for each plant in the sample, and to analyze density trends over time, by fixed-tilt versus tracking plants, and by plant latitude and site irradiance. We find that the median power density increased by 52% for fixed-tilt plants and 43% for tracking plants from 2011 to 2019, while the median energy density increased by 33% for fixed-tilt and 25% for tracking plants over the same period. Those relying on the earlier benchmarks published nearly a decade ago are, thus, significantly overstating the land requirements of utility-scale PV.
Land degradation in the Sahel threatens livelihoods and food security. The Great Green Wall programme is a colossal initiative to restore 100 million hectares of degraded ecosystems across 11 countries in the region, which started in 2007 to also promote sustainable development and climate change mitigation. We evaluated the economic costs and benefits of future land restoration projects under this programme. We applied different scenarios that account for both market-priced and non-market benefits from restored ecosystems and consider the heterogeneity of local decision-making contexts in terms of investment planning horizons, discount rates, and the time needed for the restored ecosystems to start yielding their benefits in full. The results show that every US dollar invested into land restoration yields on average US1.1 to US44 billion is needed under the base scenario (US$18–70 billion across scenarios). Violent conflicts in the Sahel are estimated to reduce the accessibility to these degraded ecosystems from 27.9 million hectares to 14.1 million hectares. The study highlights activities and locations where land restoration is both economically attractive and ecologically sustainable, even after accounting for lower survival rates of planted trees and grasses, persistence of land degradation drivers and the growing number of violent conflicts hindering land restoration in the Sahel. This information can help improve the targeting of future land restoration activities in the region.
Access to safely managed drinking water (SMDW) remains a global challenge, and affects 2.2 billion people1,2. Solar-driven atmospheric water harvesting (AWH) devices with continuous cycling may accelerate progress by enabling decentralized extraction of water from air3–6, but low specific yields (SY) and low daytime relative humidity (RH) have raised questions about their performance (in litres of water output per day)7–11. However, to our knowledge, no analysis has mapped the global potential of AWH12 despite favourable conditions in tropical regions, where two-thirds of people without SMDW live2. Here we show that AWH could provide SMDW for a billion people. Our assessment—using Google Earth Engine13—introduces a hypothetical 1-metre-square device with a SY profile of 0.2 to 2.5 litres per kilowatt-hour (0.1 to 1.25 litres per kilowatt-hour for a 2-metre-square device) at 30% to 90% RH, respectively. Such a device could meet a target average daily drinking water requirement of 5 litres per day per person14. We plot the impact potential of existing devices and new sorbent classes, which suggests that these targets could be met with continued technological development, and well within thermodynamic limits. Indeed, these performance targets have been achieved experimentally in demonstrations of sorbent materials15–17. Our tools can inform design trade-offs for atmospheric water harvesting devices that maximize global impact, alongside ongoing efforts to meet Sustainable Development Goals (SDGs) with existing technologies. Mapping of the global potential of atmospheric water harvesting using solar energy shows that it could provide safely managed drinking water for a billion people worldwide based on climate suitability.
Sustainable energy systems form an indispensable component of sustainable development especially in developing economies. Understanding the system wide techno-economics of sustainable energy systems therefore becomes critical in shaping the energy system mix within a region or country. This paper explores progressive and optimal pathways towards a fully sustainable energy system for Cameroon by 2050 in power, heat, and transport sectors as a representative case study for the Central Africa region. Six key scenarios are modelled with the LUT Energy System Transition Model to capture key policy and sustainability constraints. Results from the study show that, the optimal least cost technology combination for a fully sustainable energy system for Cameroon with net-zero greenhouse gas emissions in 2050 is dominated by solar PV (86%), complemented by hydropower (8%) and bioenergy (5%). These results show that a fully sustainable energy system for Cameroon is feasible from both the technical and economic perspectives, if policy commitment is oriented towards these low-cost energy solutions. The results of this research provide a reliable reference for planning transitions towards a 100% renewable energy-based energy system in countries within the Central Africa region.
The ongoing development of the Global Carbon Project (GCP) global methane (CH4) budget shows a continuation of increasing CH4 emissions and CH4 accumulation in the atmosphere over 2000‐2017. Here we decompose the global budget into 19 regions (18 land and one oceanic) and five key source sectors to spatially attribute the observed global trends. A comparison of top‐down (atmospheric and transport model‐based) and bottom‐up (inventory‐ and process model‐based) CH4 emissions estimates demonstrates robust temporal trends with CH4 emissions increasing in 16 of the 19 regions. Five regions ‐ China, Southeast Asia, USA, South Asia, and Brazil ‐ account for > 40% of the global total emissions (their anthropogenic and natural sources together totalling > 270 Tg CH4 yr‐1 in 2008‐2017). Two of these regions, China and South Asia, emit predominantly anthropogenic emissions (> 75%) and together emit more than 25% of global anthropogenic emissions. China and the Middle East show the largest increases in total emission rates over the 2000 to 2017 period with regional emissions increasing by > 20%. In contrast, Europe and Korea & Japan, show a steady decline in CH4 emission rates, with total emissions decreasing by ~10% between 2000 and 2017. Coal mining, waste (predominantly solid waste disposal) and livestock (especially enteric fermentation) are dominant drivers of observed emissions increases while declines appear driven by a combination of waste and fossil emission reductions. As such, together these sectors present the greatest risks of further increasing the atmospheric CH4 burden and the greatest opportunities for greenhouse gas abatement.
The aim of this research is to analyse the impact of renewable energy (RE) technologies and sector coupling via analysing the transition pathways towards a sustainable energy system in Chile. Four energy transition scenarios for the power, heat, transport and desalination sectors were assessed using the LUT Energy System Transition model. The current policy scenario was modelled and compared with three best policy scenarios. The results showed that the transition to a 100 % renewable-based energy system by 2050 is technically feasible. Further, such an energy system would be more cost-efficient than the current policy scenario to reach carbon neutrality by 2050. The results also indicate that Chile could reach carbon neutrality by 2030 and become a negative greenhouse gas emitter country by 2035. In a 100 % renewable-based energy system, solar photovoltaics (PV) would contribute 86 % of electricity generation, which would represent 83 % of the total final energy demand for the year 2050. This would imply the use of about 10 % of the available techno-economic RE potential of the country. Three vital elements (high level of renewable electrification across all sectors, flexibility and RE-based fuel production) and three key enablers (solar PV, interconnection and full sectoral integration) were identified in order to transition to a fully sustainable energy system. Chile could contribute to the global sustainable energy transition and advance to the global post-fossil fuels economy through the clean extraction of key raw materials and RE-based fuels and chemicals production.
Climate change threats and the necessity to achieve global Sustainable Development Goals demand unprecedented economic and social shifts around the world, including a fundamental transformation of the global energy system. An energy transition is underway in most regions, predominantly in the power sector. This research highlights the technical feasibility and economic viability of 100% renewable energy systems including the power, heat, transport and desalination sectors. It presents a technology-rich, multi-sectoral, multi-regional and cost-optimal global energy transition pathway for 145 regional energy systems sectionalised into nine major regions of the world. This 1.5°C target compatible scenario with rapid direct and indirect electrification via Power-to-X processes and massive defossilisation indicates substantial benefits: 50% energy savings, universal access to fresh water and low-cost energy supply. It also provides an energy transition pathway that could lead from the current fossil-based system to an affordable, efficient, sustainable and secure energy future for the world.
This paper analyses the role of sector coupling towards 2050 in the energy system of Northern-central Europe when pursuing the green transition. Impacts of restricted onshore wind potential and transmission expansion are considered. Optimisation of the capacity development and operation of the energy system towards 2050 is performed with the energy system model Balmorel. Generation, storage, transmission expansion, district heating, carbon capture and storage, and synthetic gas units compete with each other. The results show how sector coupling leads to a change of paradigm: The electricity system moves from a system where generation adapts to inflexible demand, to a system where flexible demand adapts to variable generation. Sector coupling increases electricity demand, variable renewable energy, heat storage capacity, and electricity and district heating transmission expansion towards 2050. Non-restricted investments in onshore wind and electricity transmission reduce emissions and costs considerably (especially with high sector coupling) with savings of 78.7€2016/person/year. Investments in electric power-to-heat units are key to reduce costs and emissions in the heat sector. The scenarios with the highest sector coupling achieve the highest emission reduction by 2045: 76% greenhouse gases reduction with respect to 1990 levels, which highlights the value of sector coupling to achieve the green transition.
Our carbon-intensive economy has led to an average temperature rise of 1 °C since pre-industrial times. As a consequence, the world has seen increasing droughts, significant shrinking of the polar ice caps, and steady sea-level rise. To stall these issues’ worsening further, we must limit global warming to 1.5 °C. In addition to the economy’s decarbonization, this endeavour requires the use of negative-emissions technologies (NETs) that remove the main greenhouse gas, carbon dioxide, from the atmosphere. While techno-economic feasibility alone has driven the definition of negative-emissions solutions, NETs’ diverse, far-reaching implications demand a more holistic assessment. Here, we present a comprehensive framework, integrating NETs’ critical performance aspects of feasibility, effectiveness, and side impacts, to define the optimal technology mix within realistic outlooks. The resulting technology portfolios provide a useful new benchmark to compare carbon avoidance and removal measures and deliberately choose the best path to solve the climate emergency.
Transition towards long-term sustainable energy systems is one of the biggest challenges faced by the global society. By 2050, not only greenhouse gas emissions have to be eliminated in all energy sectors: power, heat, transport and industry but also these sectors should be closely coupled allowing maximum synergy effects and efficiency. A tool allowing modelling of complex energy system transition for power, heat, transport and industry sectors, responsible for over 75% of the CO2eq emissions, in full hourly resolution, is presented in this research and tested for the case of Kazakhstan. The results show that transition towards a 100% sustainable and renewable energy based system by 2050 is possible even for the case of severe climate conditions and an energy intensive industry, observed in Kazakhstan. The power sector becomes backbone of the entire energy system, due to more intense electrification induced sector coupling. The results show that electrification and integration of sectors enables additional flexibility, leading to more efficient systems and lower energy supply cost, even though integration effect varies from sector to sector. The levelised cost of electricity can be reduced from 62 €/MWh in 2015 to 46 €/MWh in 2050 in a fully integrated system, while the cost of heat stays on a comparable level within the range of 30–35 €/MWh, leading to an energy system cost on a level of 40–45 €/MWh. Transition towards 100% renewable energy supply shrinks CO2eq emissions from these sectors to zero in 2050 with 90% of the reduction achieved by 2040.
Water is essential to the progress of human societies. It is required for a healthy environment and a thriving economy. Food production, electricity generation, and manufacturing, among other things, all depend on it. However, many decision-makers lack the technical expertise to fully understand hydrological information. In response to growing concerns from the private sector and other actors about water availability, water quality, climate change, and increasing demand, WRI applied the composite index approach as a robust communication tool to translate hydrological data into intuitive indicators of water-related risks. This technical note serves as the main reference for the updated Aqueduct™ water risk framework, in which we combine 13 water risk indicators—including quantity, quality, and reputational risks—into a composite overall water risk score. The main audience for this technical note includes users of the Aqueduct tool, for whom the short descriptions on the tool and in the metadata document are insufficient. This technical note lays out the design of the Aqueduct water risk framework, explains how various data sources are transformed into water risk indicators, and covers how the indicators are aggregated into composite scores. This document does not explore the differences with the previous version. The resulting database and online tools enable comparison of water-related risks across large geographies to identify regions or assets deserving of closer attention. Aqueduct 3.0 introduces an updated water risk framework and new and improved indicators. It also features different hydrological sub-basins. We introduce indicators based on a new hydrological model that now features (1) integrated water supply and demand, (2) surface water and groundwater modeling, (3) higher spatial resolution, and (4) a monthly time series that enables the provision of monthly scores for selected indicators. Key elements of Aqueduct, such as overall water risk, cannot be directly measured and therefore are not validated. Aqueduct remains primarily a prioritization tool and should be augmented by local and regional deep dives.
Background:
Biomass maps are valuable tools for estimating forest carbon and forest planning. Individual-tree biomass estimates made using allometric equations are the foundation for these maps, yet the potentially-high uncertainty and bias associated with individual-tree estimates is commonly ignored in biomass map error. We developed allometric equations for lodgepole pine (Pinus contorta), ponderosa pine (P. ponderosa), and Douglas-fir (Pseudotsuga menziesii) in northern Colorado. Plot-level biomass estimates were combined with Landsat imagery and geomorphometric and climate layers to map aboveground tree biomass. We compared biomass estimates for individual trees, plots, and at the landscape-scale using our locally-developed allometric equations, nationwide equations applied across the U.S., and the Forest Inventory and Analysis Component Ratio Method (FIA-CRM). Total biomass map uncertainty was calculated by propagating errors from allometric equations and remote sensing model predictions. Two evaluation methods for the allometric equations were compared in the error propagation—errors calculated from the equation fit (equation-derived) and errors from an independent dataset of destructively-sampled trees (n = 285).
Results:
Tree-scale error and bias of allometric equations varied dramatically between species, but local equations were generally most accurate. Depending on allometric equation and evaluation method, allometric uncertainty contributed 30–75% of total uncertainty, while remote sensing model prediction uncertainty contributed 25–70%. When using equation-derived allometric error, local equations had the lowest total uncertainty (root mean square error percent of the mean [% RMSE] = 50%). This is likely due to low-sample size (10–20 trees sampled per species) allometric equations and evaluation not representing true variability in tree growth forms. When independently evaluated, allometric uncertainty outsized remote sensing model prediction uncertainty. Biomass across the 1.56 million ha study area and uncertainties were similar for local (2.1 billion Mg; % RMSE = 97%) and nationwide (2.2 billion Mg; % RMSE = 94%) equations, while FIA-CRM estimates were lower and more uncertain (1.5 billion Mg; % RMSE = 165%).
Conclusions:
Allometric equations should be selected carefully since they drive substantial differences in bias and uncertainty. Biomass quantification efforts should consider contributions of allometric uncertainty to total uncertainty, at a minimum, and independently evaluate allometric equations when suitable data are available.
While we increasingly turn to desalination as a secure water supply, it is still perceived as an expensive and environmentally damaging solution, affordable only for affluent societies. In this contribution, we recast desalination from one of a last resort to a far-reaching, climate change mitigating, water security solution.
First, we argue that the benefits of desalination go beyond the single-use value of the water produced. If coupled with water reuse for irrigation, desalination reduces groundwater abstraction and augments the water cycle. As such, it may support both adaptation to, and mitigation of climate change impacts by deploying plentiful water for human use, with all the benefits that entails, while helping preserve and restore ecosystems.
Second, we counter two arguments commonly raised against desalination, namely its environmental impact and high cost.
The environmental impact can be fully controlled so as not pose long-term threats, if driven by renewable energy. Desalination may then have a zero carbon footprint. Moreover, appropriately designed outfalls make the disposal of brine at sea compatible with marine ecosystems. Recovery of energy, minerals and more water from brine reject (particularly in the form of vapour for cooling to enable more crops and vegetation to grow), while possible, is often hardly economically justified. However, resource recovery may turn more attractive in the future, and help reduce the brine volumes to dispose.
When fresh water becomes scarce, its cost tends to go up, making desalination increasingly economic. Moreover, desalination can have virtually no environmental costs. Considering the environmental costs of over-abstraction of freshwater, desalination tilts the balance in its favour.
In the future, the Sahara and Sahelian regions could experience more rainfall than today as a result of climate change. Wetter periods, termed African humid periods, occurred in the past and witnessed a mesic landscape in place of today’s hyperarid and semiarid environment. Such large past changes raise the question of whether the near future might hold in store similar environmental transformations, particularly in view of the growing human-induced climate, land-use, and land-cover changes. In the last decades, geoengineering initiatives (in the form of active re-greening projects of the Sahara and Sahel) have been proposed and could have significant effects on the climate of the region. Here, we synthesize the literature on past and projected changes in the hydroclimate of the Sahelian-Saharan region and the associated feedbacks. We further address the current state of knowledge concerning Saharan and Sahelian afforestation projects and their consequences. Our review underscores the importance of vegetation in land-atmosphere-ocean feedback processes and the far-field impacts of northern African ecosystem changes.
This research explores the feasibility of 100% renewable energy (RE) systems for the Middle East and North Africa (MENA) region for assumptions of the year 2030. The demand for three sectors are taken into account: power, non-energetic industrial gas and seawater desalination. Three strategical scenarios are discussed, namely Region, Area and Integrated, mainly differing in level of regional grid interconnection and sector coupling. Solar photovoltaics (PV) and wind energy are found to be the most cost-competitive RE sources with the highest potential in the region covering more than 90% of the generation capacity in all the considered scenarios. The variability of RE is solved via energy storage, surplus electricity generation and electricity grids. The estimated overall levelised cost of electricity (LCOE) lies between 40.3 and 52.8 €/MWh, depending on the scenarios. The total LCOE decreased by 17% as a result of sector coupling compared to the interconnected power sector alone. Power-to-gas technology not only functions as a seasonal storage by storing surplus electricity produced mainly from wind power and partially from solar PV, but provides also the required gas for the non-energetic industrial gas sector. Battery storage complements solar PV as a diurnal storage to meet the electricity demand during the evening and night time. Seawater reverse osmosis desalination powered by renewables could potentially be a proper solution to overcome the water challenges in the MENA region at affordable cost of 1.4 €/m³. A comparison with a BAU strategy shows that a 100% renewable energy-based power system is 55–69% cheaper than a BAU strategy without and with greenhouse gas emission costs.
Christian Breyer is Professor for Solar Economy at LUT University, Finland. His major expertise is research of technological and economic characteristics of renewable energy systems specializing for highly renewable energy systems, on a local but also global scale. Research includes integrated sector analyses with power, heat, transport, desalination, industry, NETs, CCU, and Power-to-X. He worked previously for Reiner Lemoine Institut, Berlin, and Q-Cells (now Hanwha Q Cells). He is a member of ETIP PV, IEA-PVPS, scientific committee of the EU PVSEC and IRES, chairman at the Energy Watch Group, and reviewer for the IPCC.
Mahdi Fasihi, M.Sc., is Research Assistant at LUT University, Finland. His focus area is CO2 direct air capture and techno-economic assessment of renewable electricity-based Power-to-X fuels and chemicals production and global trading. Highly resolved energy system modeling is a key method for his potential assessments. He received his M.Sc. degree in Energy Technology at LUT University and B.Sc. in Mechanical Engineering at Guilan University, Iran.
Cyril Bajamundi, PhD, is Chief Technology Officer of Soletair Power Oy, a Finnish start-up company focused on CO2 direct air capture and Power-to-X fuel conversion. He had been a Senior Scientist with VTT Technical Research Center of Finland, working in direct air capture of CO2 to support power-to-gas and power-to-liquid technologies for energy storage. Previously, he worked as Assistant Professor in the Department of Chemical Engineering at the University of the Philippines, where he received his M.Sc. in Chemical Engineering.
Felix Creutzig leads a working group at the Mercator Research Institute on Global Commons and Climate Change, Berlin, and is Chair of Sustainability Economics of Human Settlements at Technical University Berlin. Educated as a physicist, he holds a PhD in Computational Neuroscience. He coordinates the chapter on “demand, services, and social aspects of mitigation” in the 6th assessment report of the IPCC. Research interests include data science and machine learning approaches for designing low-carbon cities, and demand-side solutions for climate change mitigation.
The potential for global forest cover
The restoration of forested land at a global scale could help capture atmospheric carbon and mitigate climate change. Bastin et al. used direct measurements of forest cover to generate a model of forest restoration potential across the globe (see the Perspective by Chazdon and Brancalion). Their spatially explicit maps show how much additional tree cover could exist outside of existing forests and agricultural and urban land. Ecosystems could support an additional 0.9 billion hectares of continuous forest. This would represent a greater than 25% increase in forested area, including more than 200 gigatonnes of additional carbon at maturity.Such a change has the potential to store an equivalent of 25% of the current atmospheric carbon pool.
Science , this issue p. 76 ; see also p. 24
Land-based greenhouse gas removal (GGR) options include afforestation or reforestation (AR), wetland restoration, soil carbon sequestration (SCS), biochar, terrestrial enhanced weathering (TEW), and bioenergy with carbon capture and storage (BECCS). We assess the opportunities and risks associated with these options through the lens of their potential impacts on ecosystems services (Nature's Contributions to People; NCPs) and the United Nations Sustainable Development Goals (SDGs). We find that all land-based GGR options contribute positively to at least some NCPs and SDGs. Wetland restoration and SCS almost exclusively deliver positive impacts. A few GGR options, such as afforestation, BECCS, and biochar potentially impact negatively some NCPs and SDGs, particularly when implemented at scale, largely through competition for land. For those that present risks or are least understood, more research is required, and demonstration projects need to proceed with caution. For options that present low risks and provide cobenefits, implementation can proceed more rapidly following no-regrets principles.
Expected final online publication date for the Annual Review of Environment and Resources Volume 44 is October 17, 2019. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
CO2 direct air capture (DAC) has been increasingly discussed as a climate change mitigation option. Despite technical advances in the past decade, there are still misconceptions about DAC's current and long-term costs as well as energy, water and area demands. This could undermine DAC's anticipated role in a neutral or negative greenhouse gas emission energy system, and influence policy makers. In this study, a literature review and techno-economic analyses of state-of-the-art DAC technologies are performed, wherein, DAC technologies are categorised as high temperature aqueous solutions (HT DAC) and low temperature solid sorbent (LT DAC) systems, from an energy system perspective. DAC capital expenditures, energy demands and costs have been estimated under two scenarios for DAC capacities and financial learning rates in the period 2020 to 2050. DAC system costs could be lowered significantly with commercialisation in the 2020s followed by massive implementation in the 2040s and 2050s, making them cost competitive with point source carbon capture and an affordable climate change mitigation solution. It is concluded that LT DAC systems are favourable due to lower heat supply costs and the possibility of using waste heat from other systems. CO2 capture costs of LT DAC systems powered by hybrid PV-Wind-battery systems for Moroccan conditions and based on a conservative scenario, without/with utilisation of free waste heat are calculated at 222/133, 105/60, 69/40 and 54/32 €/tCO2 in 2020, 2030, 2040 and 2050, respectively. These new findings could enhance DAC's role in a successful climate change mitigation strategy.
While a rapid decommissioning of fossil fuel technologies deserves priority, most climate stabilization scenarios suggest that negative emission technologies (NETs) are required to keep global warming well below 2°C. Yet, current discussions on NETs are lacking a distinct energy perspective. Prominent NETs, such as bioenergy with carbon capture and storage (BECCS) and direct air carbon capture and storage (DACCS), will integrate differently into the future energy system, requiring a concerted research effort to determine adequate means of deployment. In this perspective, we discuss the importance of energy per carbon metrics, factors of future cost development, and the dynamic response of NETs in intermittent energy systems. The energy implications of NETs deployed at scale are massive, and NETs may conceivably impact future energy systems substantially. DACCS outperform BECCS in terms of primary energy required per ton of carbon sequestered. For different assumptions, DACCS displays a sequestration efficiency of 75-100%, whereas BECCS displays a sequestration efficiency of 50-90% or less if indirect land use change is included. Carbon dioxide removal costs of DACCS are considerably higher than BECCS, but if DACCS modularity and granularity helps to foster technological learning to <100$/tCO2, DACCS may remove CO2 at gigaton scale. DACCS also requires two magnitudes less land than BECCS. Designing NET systems that match intermittent renewable energies will be key for stringent climate change mitigation. Our results contribute to an emerging understanding of NETs that is notably different to that derived from scenario modelling.
Pathways for achieving the 1.5–2 °C global temperature moderation target imply a massive scaling of carbon dioxide (CO2) removal technologies, in particular in the 2040s and onwards. CO2 direct air capture (DAC) is among the most promising negative emission technologies (NETs). The energy demands for low-temperature solid-sorbent DAC are mainly heat at around 100 °C and electricity, which lead to sustainably operated DAC systems based on low-cost renewable electricity and heat pumps for the heat supply. This analysis is carried out for the case of the Maghreb region, which enjoys abundantly available low-cost renewable energy resources. The energy transition results for the Maghreb region lead to a solar photovoltaic (PV)-dominated energy supply with some wind energy contribution. DAC systems will need the same energy supply structure. The research investigates the levelised cost of CO2 DAC (LCOD) in high spatial resolution and is based on full hourly modelling for the Maghreb region. The key results are LCOD of about 55 €/tCO2 in 2050 with a further cost reduction potential of up to 50%. The area demand is considered and concluded to be negligible. Major conclusions for CO2 removal as a new energy sector are drawn. Key options for a global climate change mitigation strategy are first an energy transition towards renewable energy and second NETs for achieving the targets of the Paris Agreement.
A major renewable-energy milestone occurred in 2022: Photovoltaics (PV) exceeded a global installed capacity of 1 TW dc. But despite considerable growth and cost reduction over time, PV is still a small part of global electricity generation (4 to 5% for 2022), and the window is increasingly closing to take action at scale to cut greenhouse gas (GHG) emissions while meeting global energy needs for the future. PV is one of very few options that can be dispatched relatively quickly, but discussions of TW-scale growth at the global level may not be clearly communicating the needed size and speed for renewable-energy installation. A major global risk would be to make poor assumptions or mistakes in modeling and promoting the required PV deployment a n d i n d u s t r y g r o w t h a n d then realize by 2035 that we were profoundly wrong on the low side and need to ramp up manufacturing and deployment to unrealistic or unsustainable levels.
The increasing demand for water in urban and industrial areas in arid and semiarid coastal zones has led to the search for alternative nonconventional water resources.. Desalination plants are the most feasible solution to the huge water demand in arid regions, especially in Egypt, with its limited water resources of the Nile River and expected drought due to climate change and upstream dam construction. Many desalination technologies, such as thermal and membrane technologies, are used. Thermal desalination includes multistage flash desalination, multi-effect desalination, and desalination by vapor compression. Membrane desalination involves RO, forward osmosis, and electro dialysis. (RO) desalination plants are the most significant technique for desalinated water in Egypt. However, the treatment of brine wastewater is still a challenging problem. Hypersaline water effluent, as a byproduct of seawater desalination, has a negative impact on the marine ecosystem if it is discharged inadequately. In the past decade, Egypt has launched many large-scale projects along Red Sea and Mediterranean coasts to cope the recent economic growth.
In this research a review of taxonomy of many related publications, and comparison has been made between the different seawater desalination techniques to determine the advantages and disadvantages of each of them, as well as to know the best technology that can be used in Egypt. The Egyptian state's plan to address the excessive demand for water resources as a result of the continuous population growth was reviewed by making a strategic plan for 30 years. It was divided into five-year plans, some parts of which have been completed, and the rest of the plan is being completed to present significant comparisons and enable the derivation of informative conclusions.
A study was conducted on three species (Khaya senegalensis, Corymbia citriodora and Casuarina equisetifolia) planted in desert lands of Egypt and irrigated with basic treated municipal wastewater. Every single tree is permanently drip irrigated and at the same time fertilised by the nutrient-rich wastewater. Trees of different classes of the diameter at breast height (eight for each species) were felled to determine the form factor and stem volume, as well as the biomass and carbon sequestration of stem, crown and root of the individual trees. In addition, a scenario for the development of un-thinned stands from ages 5 to 35 years was constructed. The age of the sample trees at felling was: 128, 66 and 82 months for K. senegalensis, C. citriodora and C. equisetifolia, respectively. The vigorous sampled trees had a stem volume of 0.289, 0.162 and 0.229 m³ and an aboveground and belowground biomass of 451, 161 and 264 kg for K. senegalensis, C. citriodora and C. equisetifolia, respectively. Results of the scenario showed an unexpectedly high growth rate of afforestation in desert lands using municipal wastewater. At the age of 25, the stem volume for all three species exceeds 398 m³/ha. At the same age of 25 years, K. senegalensis, C. citriodora and C. equisetifolia sequester 1131, 1068 and 860 CO2 t/ha, respectively. Afforestation in desert areas presents a unique situation in forestry, as growth is stimulated by sufficient sunlight, water and nutrients. Competition for water and nutrients is strongly diminished. Self-thinning of stands under such conditions is expected to be much slower than in rain-fed plantation forests. On the other hand, tree maturity span is curtailed. This opens new possibilities for different forest management and practices towards resilient forest-based mitigation of climate change. For its unexpected role as an effective mitigation measure, afforestation in desert lands should be encouraged and further research conducted.
Thanks to fast learning and sustained growth, solar photovoltaics (PV) is today a highly cost-competitive technology, ready to contribute substantially to CO 2 emissions mitigation. However, many scenarios assessing global decarbonization pathways, either based on integrated assessment models or partial-equilibrium models, fail to identify the key role that this technology could play, including far lower future PV capacity than that projected by the PV community. In this perspective, we review the factors that lie behind the historical cost reductions of solar PV and identify innovations in the pipeline that could contribute to maintaining a high learning rate. We also aim at opening a constructive discussion among PV experts, modelers, and policymakers regarding how to improve the representation of this technology in the models and how to ensure that manufacturing and installation of solar PV can ramp up on time, which will be crucial to remain in a decarbonization path compatible with the Paris Agreement.
This study analyses the role that renewable energy based desalination, in conjunction with improvements in water use efficiency in the irrigation sector, can play towards securing future global water supplies. It is found that the global desalination demand by 2050 can be reduced by much as 30% and 60%, depending on the irrigation efficiency growth rate. India, China, USA, Pakistan and Iran account for between 56% and 62% of the global desalination demand. Decarbonising the desalination sector by 2050, will result in global average levelised cost of water decreasing from about 2.4 €/m³ in 2015, considering unsubsidised fossil fuel costs, to approximately 1.05 €/m³ by 2050, with most regions in the cost range of 0.32 €/m³ – 1.66 €/m³. Low-cost renewable electricity, in particular solar photovoltaics and battery storage, is found to form the backbone of a sustainable and clean global water supply, supported by measures to increase irrigation efficiency. The results show the untapped relationships between the irrigation and decarbonised desalination sector that can be utilised to strengthen the global water supply for the decades to come and meet United Nations Sustainable Development Goals.
Afforestation is considered a cost‐effective and readily available climate change mitigation option. In recent studies afforestation is presented as a major solution to limit climate change. However, estimates of afforestation potential vary widely. Moreover, the risks in global mitigation policy and the negative trade‐offs with food security are often not considered. Here, we present a new approach to assess the economic potential of afforestation with the IMAGE 3.0 integrated assessment model framework. In addition, we discuss the role of afforestation in mitigation pathways and the effects of afforestation on the food system under increasingly ambitious climate targets. We show that afforestation has a mitigation potential of 4.9 GtCO2/yr at 200 US$/tCO2 in 2050 leading to large‐scale application in an SSP2 scenario aiming for 2°C (410 GtCO2 cumulative up to 2,100). Afforestation reduces the overall costs of mitigation policy. However, it may lead to lower mitigation ambition and lock‐in situations in other sectors. Moreover, it bears risks to implementation and permanence as the negative emissions are increasingly located in regions with high investment risks and weak governance, for example in Sub‐Saharan Africa. Afforestation also requires large amounts of land (up to 1,100 Mha) leading to large reductions in agricultural land. The increased competition for land could lead to higher food prices and an increased population at risk of hunger. Our results confirm that afforestation has substantial potential for mitigation. At the same time, we highlight that major risks and trade‐offs are involved. Pathways aiming to limit climate change to 2°C or even 1.5°C need to minimize these risks and trade‐offs in order to achieve mitigation sustainably.
By 2050, it is estimated that the annual cereal production would need to increase by about 140% and total global food production increase by 70%. Meanwhile, total water withdrawals for irrigation is projected to increase by 11%. In contrast, poor management of existing water resources, pollution and climate change has resulted in limited freshwater resources. The aim of this paper is to assess how improved irrigation efficiency and renewable energy based desalination maybe used to secure future water supplies for the growth of rice, wheat and maize.
The efficiencies of the existing irrigation sites were obtained and improved based on a logistic curve. The growth was projected such that by 2050, all existing irrigation sites would have an efficiency of 90%. The new irrigation efficiencies were used to obtain the reduced irrigation demand for the years 2030 and 2050. The desalination demand was estimated and an energy system model used to optimise the corresponding renewable energy based power system.
It was found that improving the average irrigation efficiency to 60% by 2030, led to a 64% reduction in total desalination demand. Similarly, an improvement towards 90% irrigation efficiency, by 2050, translates to an 80% reduction in global desalination demand. In 2030, the total water cost is mostly within 0.7 €/m3 – 2 €/m3 including water transportation costs. Literature reports that farmers may be willing to pay up to 0.63 €/m3 for their irrigation water. The global range in 2050 is estimated to be 0.45 €/m3 – 1.7 €/m3 reflecting the lower system costs in 2050.
The above results indicate that as conventional water prices increase, renewable energy based seawater reverse osmosis desalination, offers a cost effective water supply for the irrigation sector. Adoption of high efficiency irrigation systems alleviate water stress and can eliminate need for additional water supply.