Term Carbon Storage Research Articles

Effect of climatic factors on leaf litter decomposition dynamics of a subtropical scrub forest under field and microcosm conditions

This study investigated the leaf litter decomposition dynamics of Hayat-ul-Mir subtropical scrub forest in Pakistan. Litter bags were incubated for 360 days in the forest to elucidate the effect of elevation and incubation time and for 90 days in microcosms to investigate the effect of projected warming (+2.3°C and +4.5°C) and soil moisture (M15% and M20%) on litter decomposition. Site elevation significantly affected k and T50% while time affected mass loss, residual weight, remaining C and N at p < .01 in field. After 360 days of decomposition, ∼48% residual weight with 11.7 ± 0.4% of C and 1.07 ± 0.06% of N was observed in the litter bags. Higher elevations (850–1020 m) were recorded with low C and N mineralization compared to 600–850 m elevations indicating their potential for long term carbon storage. Warming (+4.5°C) significantly accelerated the pace of decomposition in microcosms with comparatively higher mass loss (+26%), k (+34%), and soil CO2 efflux (+50%) reducing T50% by 77 days than observed under ambient conditions (To). The effect of moisture was insignificant but comparatively, decomposition was high at M20%. The study concludes that future warming will significantly accelerate the pace of nutrient cycling reducing the carbon storage potential of this ecosystem.

The potential of seaweed cultivation to achieve carbon neutrality and mitigate deoxygenation and eutrophication

Carbon neutrality has been proposed due to the increasing concerns about the consequences of rising atmospheric CO2. Previous studies overlooked the role of lost particle organic carbon (POC) and excreted dissolved organic carbon (DOC) from seaweed cultivation in carbon sequestration, that is to say, long term carbon storage in the oceanic sediments and in the water. This study assessed the potential of seaweed cultivation to achieve carbon neutrality of China by 2060 using a new method that included lost POC and excreted DOC. Based on the seaweed production in the years 2015–2019 in China, harvested seaweed removed 605 830 tonnes of carbon, 70 615 tonnes of nitrogen and 8 515 tonnes of phosphorus from seawaters annually; farmed seaweed sequestrated 344 128 tonnes of carbon and generated 2533 221 tonnes of oxygen annually. Among the seven farmed seaweeds, Gracilariopsis lemaneiformis has the highest capacities for carbon removal (9.58 tonnes ha−1 yr−1) and sequestration (5.44 tonnes ha−1 yr−1) and thus has the smallest cultivation area required to sequestrate 2.5 Gt CO2 that is annually required to achieve China’s carbon neutrality goal by 2060. The O2 generated by seaweed cultivation could increase dissolved oxygen in seawaters (0–3 m deep) by 21% daily with gas exchange excluded, which could effectively counteract deoxygenation in seawaters. Gracilariopsis lemaneiformis also has the highest N removal capacity while Saccharina japonica has the highest P removal capacity. To completely absorb the N and P released from the fish mariculture, a production level or a cultivation area two and three times larger (assuming productivity remains unchanged) would be required. This study indicates that seaweed cultivation could play an important role in achieving carbon neutrality and mitigating deoxygenation and eutrophication in seawaters. Cultivation cost could be offset to some extent by increased sales of the harvest parts of the seaweed for food and biofuel.

Prediction of the lifespan of cement at a specific depth based on the coupling of geomechanical and geochemical processes for CO2 storage

The injection of carbon dioxide (CO2) captured from combustion-based processes into underground formations is one of a number of plausible methods to reduce its release into the atmosphere and consequential greenhouse gas warming. Once the gas has been captured efficiently and effectively, depleted oil and gas reservoirs are seen as high potential candidates for carbon storage projects. However, legacy issues associated with a high number of oil and gas wells abandoned during the last few decades put the carbon capture and storage projects (CCS) at risk. These include any defects within the cement surrounding the well casing or for capping an abandoned well that can become unwanted CO2 leakage pathways. To predict the lifespan of these cements due to exposure to CO2-bearing fluids at the conditions found underground, the geochemical processes need to be coupled with the geomechanical changes within the cement matrix. In a viable CCS project for sequestering CO2, the cement matrix should be capable of withstanding acidic environments formed by dissolution of CO2 in brine for more than ten thousand years. This work aims at providing a framework to predict the behaviour of cement due to CO2 exposure under reservoir conditions. The results show that the chemical reactions and geomechanical changes within the cement matrix can result either in its radial cracking or radial compaction. Both of these behaviours are investigated as possible phenomena which may affect the CO2 leakage, and therefore the viability of the site for long term carbon storage.

Effects of Invasive Spartina alterniflora Loisel. and Subsequent Ecological Replacement by Sonneratia apetala Buch.-Ham. on Soil Organic Carbon Fractions and Stock

Background and Objectives: The rapid spread of invasive Spartina alterniflora Loisel. in the mangrove ecosystems of China was reduced using Sonneratia apetala Buch.-Ham. as an ecological replacement. Here, we studied the effects of invasion and ecological replacement using S. apetala on soil organic carbon fractions and stock on Qi’ao Island. Materials and Methods: Seven sites, including unvegetated mudflat and S. alterniflora, rehabilitated mangroves with different ages (one, six, and 10 years) and mature native Kandelia obovata Sheue, Liu, and Yong areas were selected in this study. Samples in the top 50 cm of soil were collected and then different fractions of organic carbon, including the total organic carbon (TOC), particulate organic carbon (POC), soil water dissolved carbon (DOC) and microbial biomass carbon (MBC), and the total carbon stock were measured and calculated. Results: The growth of S. alterniflora and mangroves significantly increased the soil TOC, POC, and MBC levels when compared to the mudflat. S. alterniflora had the highest soil DOC contents at 0–10 cm and 20–30 cm and the one-year restored mangroves had the highest MBC content. S. alterniflora and mangroves both had higher soil total carbon pools than the mudflat. Conclusions: The invasive S. alterniflora and young S. apetala forests had significantly lower soil TOC and POC contents and total organic carbon than the mature K. obovata on Qi’ao Island. These results indicate that ecological replacement methods can enhance long term carbon storage in Spartina-invaded ecosystems and native mangrove species are recommended.

Assessment of Thermal Stress on Well Integrity as a Function of Size and Material Properties

Wellbore integrity is critical to long term carbon storage. During CO2 injection, changes in temperature may result in large stress variations that can damage the well, threatening its integrity. The different materials comprising the wellbore and near-wellbore environment (namely the casing, cement and surrounding rock) possess different thermal properties. Consequently, there can be considerable variations in both material properties and thermal gradients across these layers, resulting in different amounts of contraction and expansion of these materials. This may generate sufficient thermal stresses to lead to fracture within the cement and/or host rock, or delamination of the cement/casing or cement/rock interfaces. Downsized wellbore samples have been used in laboratory studies to investigate the failure modes and failure criteria during thermal cycling operations. However, it is not clear to what extent such results can be reliably used to predict well failure at field scale conditions. In this work, we conduct a parameter study involving the size and material properties of the wellbore samples subjected to different rates of thermal loading, with the objective of predicting how these parameters can affect the thermal stress in field scale well conditions.A state-of-the-art parallel multiscale, multiphysics code named GEOS, developed at Lawrence Livermore National Laboratory, was used to study the thermal response of wellbore materials. A finite element solver considering linear elastic materials was coupled with a finite volume heat equation solver to simulate the wellbore deformation and fracture during thermal cycling. To understand the effect of wellbore size on thermal fracturing, simulations were conducted at different height to diameter ratios. The wellbore sample size was systematically varied from the lab scale to field scale with several intermediate scales. The change in thermal stresses were compared for different scales. Additionally, the effect of elastic modulus and cooling rates were studied.

Biochar Pellet Carbon Footprint

Life cycle assessment of Biochar was performed in this study using SimaPro software, aiming at the evaluation of the carbon footprint of biochar. Product Category rules have been developed. Data have been collected in a demonstrative slow pyrolysis plant, which is present at the University of Perugia and from field tests. The technical standard followed is ISO/TS 14067. Biochar, used as a soil amendment can improve soil health and fertility, soil structure, nutrient availability, soil-water retention capacity and is also a mechanism for long term Carbon storage in soils. Carbon sequestration in soils can be seen not only as a strategy to mitigate the global climate change, but also as a source of profit for companies via Carbon Credits. LCA is a useful tool to estimate the Carbon balance through all the Biochar life cycle. The feedstocks considered in this study is miscanthus, a perennial herbaceous energy crop. The functional unit is one ton of dry matter of initial feedstock (that is miscanthus biomass). The final carbon footprint is equal to -737 kgCO2eq/t of feedstock dried.

Modelling the long term carbon storage of a mixed forest under climate change: a meta-modelling approach.

Modelling the long term carbon storage of a mixed forest under climate change: a meta-modelling approach.

Long term carbon storage potential and CO2 sink strength of a restored salt marsh in New Jersey

The study compares the amounts of carbon fixed via photosynthesis of a restored tidal marsh to the total organic carbon remaining in sediments of a natural tidal marsh and arrives at preliminary baselines for carbon sequestration and storage over time. The Eddy-covariance method (indirect method) was used to estimate marsh canopy net ecosystem exchange (NEE) and measured an annual gross primary production of 979gCm−2, while the loss through respiration was 766gCm−2, resulting in a net uptake of 213gCm−2yr−1. Time of the day, solar irradiation, air temperature, humidity and wind direction all together explained 66% of the variation in NEE. The high marsh community of Spartina patens showed NEE to be significantly higher than the low marsh community. The net ecosystem carbon balance (NECB) over long time scales was estimated by measuring the actual amount of total organic carbon contained in dated sediment cores from a natural marsh (direct method), which resulted in a carbon accumulation rate of 192.2gm−2yr−1. Changes in total organic carbon content over time in the core sample showed that 78% of organic carbon remained stored in the sediments after 130 years and only the most recalcitrant carbon (50%) remained under storage beyond 645 years. Overall the study showed that temperate macrotidal salt marshes are net sinks of carbon with potential for long term carbon storage. The marsh turned into a carbon sink at the beginning of May and switched back to being a source in late November. The average sedimentation rate estimated from the 137 CS dating (1950s to present) was 1.4mmyr−1 which is similar to accretion rates of comparable S. patens patches in the east coast. Accretion rates derived from our study are slightly lower than the 60+ year rate of sea level rise (2.6mmyr−1) recorded by tide gauge measurements in the Northeast.

Financial analysis of Chir pine plantations for carbon offsets, timber and resin in Nepal

A financial analysis was done for Chir pine (Pinus roxburghii) plantations that produce carbon offset payments, timber and resin in a community forest context in Nepal. Results indicate that the inclusion of carbon offset payments increases rotation age and land expectation value. The optimal rotation age is approximately 35 years without including carbon offset payments, while the rotation age can increase beyond 75 years with the inclusion of carbon offset payments. The substantial change in optimal rotation age also suggests that carbon offset payments will likely change the product mix produced from Chir pine plantations. Likewise, land expectation value increases significantly with carbon offset payments indicating that local communities could benefit from such payments. The results also indicate that different assumptions about the quantity of long term carbon storage (i.e. pickling rate) have a significant impact on rotation age and land expectation value.DOI: http://dx.doi.org/10.3126/banko.v22i2.9193Banko Janakari: A Journal of Forestry Information for NepalVol. 22, No. 2, 2012 NovemberPage: 3-10Uploaded date: 12/1/2013

Potential availability of urban wood biomass in Michigan: Implications for energy production, carbon sequestration and sustainable forest management in the U.S.A.

Tree and wood biomass from urban areas is a potentially large, underutilized resource viewed in the broader social context of biomass production and utilization. Here, data and analysis from a regional study in a 13-county area of Michigan, U.S.A. are combined with data and analysis from several other studies to examine this potential. The results suggest that urban trees and wood waste offer a modest amount of biomass that could contribute significantly more to regional and national bio-economies than it does at present. Better utilization of biomass from urban trees and wood waste could offer new sources of locally generated wood products and bio-based fuels for power and heat generation, reduce fossil fuel consumption, reduce waste disposal costs and reduce pressure on forests. Although wood biomass generally constitutes a “carbon-neutral” fuel, burning rather than burying urban wood waste may not have a net positive effect on reducing atmospheric CO2 levels, because it may reduce a significant long term carbon storage pool. Using urban wood residues for wood products may provide the best balance of economic and environmental values for utilization.

Colimitation of decomposition by substrate and decomposers – a comparison of model formulations

Abstract. Decomposition of soil organic matter (SOM) is limited by both the available substrate and the active decomposer community. The understanding of this colimitation strongly affects the understanding of feedbacks of soil carbon to global warming and its consequences. This study compares different formulations of soil organic matter (SOM) decomposition. We compiled formulations from literature into groups according to the representation of decomposer biomass on the SOM decomposition rate a) non-explicit (substrate only), b) linear, and c) non-linear. By varying the SOM decomposition equation in a basic simplified decomposition model, we analyzed the following questions. Is the priming effect represented? Under which conditions is SOM accumulation limited? And, how does steady state SOM stocks scale with amount of fresh organic matter (FOM) litter inputs? While formulations (a) did not represent the priming effect, with formulations (b) steady state SOM stocks were independent of amount of litter input. Further, with several formulations (c) there was an offset of SOM that was not decomposed when no fresh OM was supplied. The finding that a part of the SOM is not decomposed on exhaust of FOM supply supports the hypothesis of carbon stabilization in deep soil by the absence of energy-rich fresh organic matter. Different representations of colimitation of decomposition by substrate and decomposers in SOM decomposition models resulted in qualitatively different long-term behaviour. A collaborative effort by modellers and experimentalists is required to identify formulations that are more or less suitable to represent the most important drivers of long term carbon storage.

Evolution of non-dissolved particulate organic matter during composting of sludge with straw

Long term composting induces loss of C and organic matter stabilisation. These two processes may have opposite effects on long term carbon storage in soils. To check whether raw materials should be composted or not before being spread on the soil, changes in particle size fractions were quantified during composting of 9tons of sewage sludge and straw. Both the mass of the fine fraction (<2μm) and the amount of carbon contained in it increased after seven months, respectively, +37% and +43%. The fine fraction contributes to carbon sequestration. A literature review supported the assumption that composting should increase long term C storage. Nevertheless, soil texture or agricultural practices modify the behaviour of this fraction. Thus, the fractionation method used for soils is relevant to predict the effect of composting as a mitigation option in greenhouse gas reduction strategies, but is not sufficient in itself.

Carbon materials obtained from self-binding sugar cane bagasse and deciduous wood residues plastics

Abstract It is demonstrated that dispersed biomass residues (bagasse, sawdust) can be processed into hard carbonaceous blocks, panels or boards with good strength and thermodynamic properties. There are two possible approaches: to mould dispersed biomass charcoal with a phenol–formaldehyde binder or to produce this material by carbonising the biomass fiberboard prepared by making use of steam explosion autohydrolysis pulp or steam explosion lignin as a binder. In the first step, steam explosion lignin, as a modifier and a binder is introduced to the lignocellulosic biomass by impregnation or during the hot pressing process to form a hard fiberboard. By subsequent carbonisation of the fiberboard panels or blocks, carbonised panels or blocks with high bending and crushing strength and suitable thermodynamic properties are obtained due to the formation of an internal lignin reinforcement in cell lumina and impregnation of cell walls with lignin solution or molten lignin. The carbonised panels demonstrate a good dimensional stability after a standard treatment with water. The bending strength of the carbonised panels after 24 h soaking in water is 93% of that in dry state. The thermodynamic properties and porosity of the carbonised panels demonstrate their suitability for use as a building material. Lignin, a natural binder of fiberboards, has proven to be suitable for preparation of cabonaceous panels and boards. In this respect new carbon building blocks and panels from moulded biomass and carbonised steam exploded biomass act as a concentrated form of long term carbon storage and will be a factor stabilizing the growing CO2 concentration in the atmosphere. [Proceedings of the First Workshop of QITS, Materials Life-Cycle and Environmentally Sustainable Development, March 2–4, Campinas, UNU/IAS San Paulo, Brazil, 1998, pp. 95–101; Proceedings of the Workshop in “Targeting Zero Emissions for the Utilization of Renewable Resources”, ANESC, Tokyo, 1999, pp. 2–11.]