Land, water and carbon footprints of circular bioenergy production systems

Renewable energy sources can help combat climate change but knowing the land, water and carbon implications of different renewable energy production mixes becomes a key. This paper systematically applies land, water and carbon footprint accounting methods to calculate resource appropriation and CO 2eq GHG emissions of two energy scenarios. The ‘100% scenario’ is meant as a thinking exercise and assumes a complete transition towards bioenergy, mostly as bioelectricity and some first-generation biofuel. The ‘SDS-bio scenario’ is inspired by IEA's sustainable development scenario and assumes a 9.8% share of bioenergy in the final mix, with a high share of first-generation biofuel. Energy inputs into production are calculated by differentiating inputs into fuel versus electricity and exclude fossil fuels used for non-energy purposes. Results suggest that both scenarios can lead to emission savings, but at a high cost of land and water resources. A 100% shift to bioenergy is not possible from water and land perspectives. The SDS-bio scenario, when using the most efficient feedstocks (sugar beet and sugarcane), would still require 11–14% of the global arable land and a water flow equivalent to 18–25% of the current water footprint of humanity. In comparative terms, using sugar or starchy crops to produce bioenergy results in smaller footprints than using oil-bearing crops. Regardless of the choice of crop, converting the biomass to combined heat and power results in smaller land, water and carbon footprints per unit of energy than when converting to electricity alone or liquid biofuel

Can crop residues provide fuel for future transport? Limited global residue bioethanol potentials and large associated land, water and carbon footprints

Bioethanol production from non-crop based lignocellulosic material has reached the commercial scale and is advocated as a possible solution to decarbonize the transport sector. This study evaluates how much presently used transport related fossil fuels can be replaced with lignocellulosic bioethanol using crop residues, calculates greenhouse gas emission savings, and determines lignocellulosic bioethanol's land, water, and carbon footprints. We estimate global bioethanol production potential from 123 crop residues in 192 countries and 20 territories under different environmental constraints (optimistic and realistic sustainable potentials) versus no constraints (theoretical potential) on residue availability. Previous studies on global bioethanol production potential from lignocellulosic material focused on one or few biomass feedstocks, and excluded (un)constrained residue availability scenarios. Our results suggest the global net lignocellulosic bioethanol output ranges from 7.1 to 34.0 EJ per annum replacing between 7% and 31% of oil products for transport yielding relative emission savings of 338 megatonne (Mt; 70%) to 1836 Mt (79%). Emission savings range from 4% to 23% of total transport emissions in the realistic sustainable versus theoretical potential. Land, water and carbon footprints of net bioethanol vary between potentials, countries/territories, and feedstocks, but overall exceed footprints of conventional bioethanol. Averaged footprints range between 0.14 and 0.24 m2 land per megajoule (MJ−1), 74–120 L water MJ−1, and 28–44 g CO2 equivalent MJ−1, with smaller footprints in the theoretical potential caused by the exclusion of secondary residues and low price of alternative biomass chains in the sustainable potential

Ecological impacts and limits of biomass use: a critical review

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. Conventional biomass sources have been widely exploited for several end uses (mostly food, feed, fuel and chemicals). More unconventional sources are continually being sought for meeting the growing planetary demands for biomass materials. Biofuels are already commercially produced in many countries and are becoming mainstream. The role of biorefineries for production of chemicals is also on the rise. Plant biomass is the primary source of food for all multicellular living organisms. Primary production remains a key link in the chain of life support on planet Earth. Is there enough for all? What new strategies (or technologies) are available or promising for providing plant biomass in a safe and sustainable way? What are the potential impacts (footprints and efficiencies) of such strategies? What can be the limiting factors—land, water, energy and nutrients? What might be the limits for specific regions (OECD vs. non-OECD, advanced vs. developing, dry and warm vs. wet and cool, etc.). In this paper, we provided answers to these questions by critically reviewing the pros and cons associated with current and future production and use pathways for biomass. We conclude that in many cases, the jury is still out, and we cannot come to a solid verdict about the future of biomass production and use

Conjunctive management of surface and groundwater in transboundary watercourses: a first assessment

Cooperative management of transboundary river basins is widely recognized as important. Emphasis on joint management of shared aquifers has also grown in recent years. Perhaps surprisingly, despite abundant focus on transboundary surface water and growing focus on shared groundwater, there is scant focus on their intersection. To address this knowledge limitation, this article reviews experiences in transboundary water treaties oriented toward different water sources, in order to: i) understand how transboundary water institutions vary according to the water source to which they are oriented, ii) gauge the nature and strength of conjunctive transboundary water management treaties, and iii) identify ways to enhance conjunctive water management in transboundary contexts. The results reveal the existence of more than 50 treaties that make mention of both water sources. Nonetheless, only eight treaties devote ‘substantive’ focus to both surface and groundwater. Review of treaty contents reveals that their focus is on ‘softer’ issues related to institutional development. Moving forward, the reality that the evolution of conjunctive treaties is relatively nascent, and that scope of such treaties is still limited to institutional issues, may indicate large untapped potential – it may be time to outline pathways toward practical implementation of conjunctive water management in transboundary contexts

Can crop residues provide fuel for future transport? Limited global residue bioethanol potentials and large associated land, water and carbon footprints

Bioethanol production from non-crop based lignocellulosic material has reached the commercial scale and is advocated as a possible solution to decarbonize the transport sector. This study evaluates how much presently used transport related fossil fuels can be replaced with lignocellulosic bioethanol using crop residues, calculates greenhouse gas emission savings, and determines lignocellulosic bioethanol's land, water, and carbon footprints. We estimate global bioethanol production potential from 123 crop residues in 192 countries and 20 territories under different environmental constraints (optimistic and realistic sustainable potentials) versus no constraints (theoretical potential) on residue availability. Previous studies on global bioethanol production potential from lignocellulosic material focused on one or few biomass feedstocks, and excluded (un)constrained residue availability scenarios. Our results suggest the global net lignocellulosic bioethanol output ranges from 7.1 to 34.0 EJ per annum replacing between 7% and 31% of oil products for transport yielding relative emission savings of 338 megatonne (Mt; 70%) to 1836 Mt (79%). Emission savings range from 4% to 23% of total transport emissions in the realistic sustainable versus theoretical potential. Land, water and carbon footprints of net bioethanol vary between potentials, countries/territories, and feedstocks, but overall exceed footprints of conventional bioethanol. Averaged footprints range between 0.14 and 0.24 m2 land per megajoule (MJ−1), 74–120 L water MJ−1, and 28–44 g CO2 equivalent MJ−1, with smaller footprints in the theoretical potential caused by the exclusion of secondary residues and low price of alternative biomass chains in the sustainable potential

Surface water resources

The Amu Darya and the Syr Darya are the two primary rivers draining into the Aral Sea, with a total basin area of over 1,737,000 km2, which includes parts of six states. The estimated (pre-development) mean annual flow the two rivers used to discharge into the Aral Sea was 115 km3, but the estimated current total flow is around 10 per cent of that, due to massive water resource developments in the upstream parts of the Basin, which took place primarily in the second half of the twentieth century. The existing observational meteorological and hydrological networks in the Basin are not sufficient to support informed water management. The observational networks have declined since the 1990s and have not been improved since then. Regional water data sharing is also suboptimal at present. The flows of both main rivers in the Basin are primarily meltwater-dependent. Meltwater from snow and glaciers together contributes close to 70 per cent and 80 per cent of the mean annual river flow of the Amu Darya and Syr Darya Basin, respectively. Snowmelt runoff significantly outweighs that of glaciers. The Basin contains some of the world’s most complex and largest water management infrastructure, including the world’s longest canal, the Kara Kum in Turkmenistan, and what is soon to be the world’s highest reservoir, the Rogun dam in Tajikistan (currently under construction). Water infrastructure primarily serves two economic sectors-irrigated agriculture and hydropower. The network of irrigation canals in the Basin is dense and complex, covering thousands of kilometres. There are over 80 reservoirs in the Basin with an individual capacity of over 10 million m3. Upstream riparian countries-Kyrgyzstan and Tajikistan-are implementing ambitious development plans of new hydropower facilities. A characteristic feature of water infrastructure in the region is its ageing, causing it to require costly maintenance. Tajikistan, Kyrgyzstan, Uzbekistan and Turkmenistan are among the ten most vulnerable states to climate change in Europe and Central Asia. There is high uncertainty about possible future impacts on water availability, although warming trends are already clear and flow reduction is very likely in the distant future. Future reduction of glaciers and seasonal snow cover due to climate change will most likely affect mainly the seasonality of river flow and only marginally impact mean annual flow itself in both large basins