Billion Tons Of CO2 Research Articles

Low carbon transition options for Australia

A rapid and sustained transition to new energy systems for Australia was explored using the OzECCO model implemented in a systems dynamics simulation package. OzECCO simulates the close relationship between energy use and economic productivity at a sectoral level to explore scenarios of economic and biophysical function based on a calibration period of 1981–2005 and a scenario period 2006–2051. The core scenarios showed that a fully renewable (the renewables transition) or an advanced fossil and nuclear transition (the conventional wisdom transition), can reduce accumulated CO2 emissions from the Australian economy for the period 2006–2051 by 50%. Adding a low growth economy where GDP averages less than 1% annually extends this to a 60% reduction. Extensive reforestation of more than 50 million hectares extends the total reduction to 70% over the 45 year period and provides at 2051 a per capita emissions level of one to two tonnes which will be necessary if developed and developing countries are to converge on equal atmospheric impacts with reasonable lifestyle opportunities. Central to both the renewables and conventional-wisdom scenarios are substantial reductions in the physical dimensions of personal consumption, and the transfer of these avoided consumption opportunities to an intergenerational sovereign wealth fund. This fund, held outside day-to-day domestic activities, can buffer Australian society and future generations against shocks, financial or physical, that might lie waiting and unanticipated in our future. This study did not explore phasing out Australia's extensive coal and natural gas exports although their impact on global atmospheric concentrations is significant. Domestic combustion and exported fuels will add 82 billion tonnes of CO2 to the atmosphere in the scenario period 2006–2051, equivalent to a 20 ppm rise in atmospheric concentrations. The low-growth renewables transition with unconstrained exports reduces this rise to 15 ppm. The continued expansion of fuel exports thus expands atmospheric risk in physical terms but also entrains policy and strategic risks should carbon-based industries become pariahs in international commerce and political relations.

An energy network with polygeneration system and CCS suitable for China

Abstract An energy network with polygeneration system and CCS suitable for China was proposed in our previous work in consideration of low-cost CCS and energy providing safety. In this paper, based on life-cycle analysis, the role of the Energy Network has been investigated at the national level. Results show that with the import dependency of oil controlled in the range of 40%–60% during 2020 to 2030, up to 22% of the total capacity of coal fired supercritical power plants may be replaced by hundreds of new polygeneration plants for electricity and alternative fuels. When the oil import dependency will be kept from 40% to 60%, the Energy Network can save 20%–30% of energy and cut down 30%–40% of total costs every year compared to the present method with coal fired supercritical power plants and traditional alternative fuel plants with CO 2 capture. And the Energy Network can capture more than 0.1 billion tons of CO 2 with high concentration over 98% each year. Moreover, from the aspect of CCS, this Energy Network can realize as low as 15$/t of total CCS cost due to the quite low energy penalties of CO 2 capture in the polygeneration systems and the combination of CO 2 sources and storage sites. The new Energy Network has realized the proper combination of energy utilization and CO 2 capture and storage according to the unique state of China. It is suitable for China and may play an important role in CCS in the future.

Saline-aquifer CO 2 sequestration in Japan-methodology of storage capacity assessment

A nationwide saline-aquifer CO 2 storage capacity assessment has been carried out in Japan in two missions: In Mission 1, candidate saline aquifers were classified in terms of the type of geological structure and the amount of data available. Storage capacity for the entire country was then estimated based upon oil and gas exploration data (146 billion tons of CO 2). The areas considered in the Mission were located mostly offshore and far from large CO 2 emission sources. Mission 2 involved storage capacity estimation in 27 areas in the vicinity of large CO 2 emission sources. These areas had been excluded in the Mission 1 capacity assessments. With national-scale geological survey results, a preliminary assessment was performed, and promising sedimentary basins were selected for more detailed examination. To date the overall storage capacity is still under discussion in Mission 2, whereas a systematic way of evaluating data quality and quantity is proposed, and comparative studies on the storage capacity estimation is in progress.

The power of cooperation

The power of cooperation

Combating Climate Change: What Will China’s Forestry Industry Do?

Climate change is significantly affecting our planet (Kerr 2007). Global agreements and sustained action to mitigate climate change are urgently needed (King 2004). It is well known that forests play a large role in the global carbon cycle, and thus may be of prime importance in efforts to curb climate change. Carbon storage in existing forests, carbon emissions from deforestation, and carbon sequestration through afforestation and reforestation are important issues for land use policy makers. In 2000 the Intergovernmental Panel on Climate Change (IPCC) estimated that the global carbon stock present in terrestrial ecosystems is about 2,477 Gt, of which 1,146 Gt or 46.3% is stored in forests (Watson et al. 2000). However, the terrestrial global carbon stock is constantly decreasing due to large-scale deforestation at a rate which cannot be offset by current afforestation and reforestation rates (Watson et al. 2000). Therefore, higher afforestation and reforestation rates and a lower deforestation rate must be achieved. As a responsible developing country which has the largest area of artificial forest in the world, China’s afforestation and reforestation activities have, to an extent, offset the negative impacts of deforestation in the world (FAO 2005). In China, between 1980 and 2005, approximately 3.06 billion tons of CO2 was sequestered by afforestation activities, 1.62 tons of CO2 was sequestered by forest management, and CO2 emissions were reduced by 0.43 ton due to a decrease in deforestation (Commission of Development and Reform, China Government 2007).

Membrane technologies for CO 2 separation

Today, all the existing coal-fired power plants present over the world emit about 2 billion tons of CO 2 per year. The identification of a capture process which would fit the needs of target separation performances, together with a minimal energy penalty, is a key issue. Because of their fundamental engineering and economic advantages over competing separation technologies, membrane operations are, now, being explored for CO 2 capture from power plant emissions.The aim of this work is to provide people interested in the use of membranes in CO 2 capture a general overview of the actual situation both in terms of materials studies and global strategy to follow in the choice of the membrane gas separation with respect to the other separation technologies. Firstly, an overview on the polymeric membranes currently studied for their use in CO 2 capture and of their transport properties is proposed. Up to now, the most promising materials developed at laboratory scale show a selectivity of 100–160. Then, some important design parameters have been introduced in order to evaluate the advantages potentially offered by membrane systems with respect to the other separation technologies (adsorption and cryogenic). These parameters, based on specific considerations related to the output to be obtained as the product purity and the final destination of the product and to the feed conditions, might constitute guidelines for the choice of the separation technology.Considering as case study a flue gas stream containing 13% of CO 2, some general maps of CO 2 recovery versus permeate purity have been introduced. This might constitute a simple tool useful for an immediate and preliminary analysis on the membrane technology suitability for CO 2 separation from flue gas, also on the light of specific considerations, strictly related to the output to be obtained.

WATER AND CO SHOULDN'T MIX

THE ENVIRONMENTAL Protection Agency has proposed to broaden the range of geological formations where coal-based electric utilities and companies that generate carbon dioxide may inject the greenhouse gas for sequestration. The Aug. 26 proposal allows CO 2 injection and sequestration at shallower depths that are not necessarily below drinking water aquifers, contrary to what the agency proposed a year ago. Capturing carbon dioxide and sequestering it underground is considered the only way the world can continue to burn coal and avoid the ravages of climate change. Coal supplies half of the electricity in the U.S., but it generates one-third of the 6 billion tons of CO 2 the nation emits annually. However, sequestering CO 2 underground risks damaging drinking water aquifers, and for the past year, EPA has been wrestling with development of regulations that protect groundwater and allow carbon sequestration. Water suppliers tell C&EN they don’t like EPA’s latest plan. They are worried that it won’t protect ...

Carbon Recycling: An Alternative to Carbon Capture and Storage

Introduction Carbon capture and storage (CCS) is being hailed as the answer to the globe's most pressing question: what to do with the 27 billion metric tons of carbon dioxide emitted yearly from the burning of fossil fuels? Touted as the most promising interim solution to deal with the greenhouse gas responsible for global warming, CCS still remains unproven, costly and will not be commercially available for another 10 to 20 years. Meanwhile, scientists are exploring alternatives to CCS by capitalizing on CO2 as a commodity instead of treating it as a waste. Background Twenty-seven billion tons of CO2 is already a hefty number, but energy-related carbon dioxide emissions are projected to reach 43 billion metric tons per year by 2030; an increase of 60%. A new report by the International Energy Agency (IEA) estimates that growing energy demands from emerging giants like China and India, coupled with a lack of cost-effective alternatives to fossil fuels, means that by 2050, 77% of the world's power will still be derived from fossil fuels(1). "We will require immediate policy action and a technological transition on an unprecedented scale," IEA Executive Director Nobuo Tanaka said in Tokyo after releasing the report. Carbon capture and storage (CCS), the process of capturing carbon dioxide and storing it in deep geological formations in the ocean or as mineral carbonates, is being promoted by the IEA and others as the most promising technology to deal with fossil fuel derived emissions. Not negating the role of alternative energies, the IEA is merely realistic about the enduring use of fossil fuels and the urgent need to deal with the resulting carbon dioxide. Addressing Carbon Capture and Storage On May 15th, 2009, U.S. Secretary of Energy Steven Chu announced at the National Coal Council that US$2.4 billion from the American Recovery and Reinvestment Act will be used to expand and accelerate the commercial deployment of carbon capture and storage technology, including financing to train a generation of engineers and geologists to work in the field. Chu said,: To prevent the worst effects of climate change, we must accelerate our efforts to capture and store carbon in a safe and cost-effective way." Governments in Europe, Australia, Canada and China are also strongly investing in the technology. Nevertheless, several massive hurdles still stand in the way of full-scale CCS deployment. UK consulting firm, McKinsey, figures that adding CCS to the next generation of European power plants could boost their price by up to US$1.3 billion each. Their thorough analysis(2) shows that the typical cost of a demonstration project is likely to be in the range of US$80 ? $120 per tonne of CO2 sequestered. Legally, there are concerns over whether CO2 transport and long-term storage present human or ecosystem related risks, and who is ultimately responsible if a leak occurs. While progress is underway in some countries, no country has yet developed the comprehensive, detailed legal and regulatory framework that is necessary to effectively govern the use of CCS.

Onset of Convection in CO2 Sequestration in Deep Inclined Saline Aquifers

Abstract CO2 sequestration in deep geological formations has been suggested as an option to reduce greenhouse gas emissions. Saline aquifers are one of the most promising options for carbon dioxide storage. It has been shown that the dissolution of CO2 into brine causes the density of the mixture to increase. If the corresponding Rayleigh number of the porous medium is enough to initiate convection currents, the rate of dissolution will increase. Early time dissolution of CO2 in brine is mainly dominated by molecular diffusion, while late time dissolution is predominantly governed by a convective mixing mechanism. In this paper, linear stability analysis of density-driven miscible flow for carbon dioxide sequestration in deep inclined and homogeneous saline aquifers is presented. The effect of inclination and its influence on the pattern of convection cells has been investigated and the results are compared with the horizontal layer. The current analysis provides approximations for the initial wavelength of the convective instabilities and the onset of convection that helps in selecting suitable candidates for geological CO2 sequestration sites. Introduction Carbon dioxide sequestration is the capture and safe storage of carbon dioxide that would otherwise emit to the atmosphere. Sequestration refers to any storage scheme that can keep CO2 out of the atmosphere(1). In general, proposed storage sites of carbon dioxide can be divided into two categories: geological sites and marine sites. Carbon dioxide sequestration in deep geological formations has been suggested as a way of reducing greenhouse gas emissions. Geologic sequestration of CO2 is the capture of CO2 from major sources, transporting it usually by pipeline, and injecting it into underground formations such as oil and gas reservoirs, saline aquifers and unmineable coal seams for a significant period of time(2, 3). Unlike coalbed methane reserves and oil reservoirs, sequestration of CO2 in deep saline aquifers does not produce value-added by-products, but it has other advantages. While there are uncertainties regarding the scope, the world's total capacity to store CO2 deep underground is large(4). Underground formations are generally unused and are available in many parts of the world(5). It has been estimated that deep saline formations in the United States could potentially store up to 500 billion tonnes of CO2. Most existing large CO2 point sources are within easy access to a saline formation injection point and, therefore, sequestration in saline formations is compatible with a strategy of transforming large portions of the existing energy and industrial assets to near-zero carbon emissions via low-cost carbon sequestration retrofits(3). However, it is important to investigate the behaviour of CO2 injected into aquifers for effective and safe use of storage. Geological storage of CO2 as a greenhouse gas mitigation option was proposed in the 1970s(6), but little research was done until the early 1990s when the idea gained credibility through the work of individual research groups(7–10). When CO2 is injected into the formation above its critical temperature and pressure, the density of supercritical carbon dioxide is usually less than brine. This density difference causes CO2 to migrate upwards to the top of the formation under an impermeable caprock.

Methodology of CO2 aquifer storage capacity assessment in Japan and overview of the project

Abstract A systematic Japanese nationwide saline-aquifer CO 2 storage capacity assessment has been carried out. The project was subdivided into two parts (Missions 1 and 2). We first classified the candidate saline aquifers based on the type of geological structure and the abundance of available data. A total of 146 billion tons of CO 2 storage capacity was estimated for the entire country based on oil and gas exploration data using the volumetric method in Mission 1. The potential areas considered in the Mission 1 program are mostly offshore and located far from large scale CO 2 emission sources. Mission 2 involved storage capacity estimation for regions near large scale CO 2 sources, and the Mission 2 study areas were excluded from the Mission 1 capacity assessments. A total of 27 areas that involve nearby CO 2 sources were chosen for the study. A preliminary assessment was performed based on national-scale geological information, and promising sedimentary regions were selected for more detailed examination. Detailed studies were performed for 14 promising areas based on available existing geological data, and regional-scale storage capacities were estimated. A wide range of estimated storage capacities for the various areas emerged, from 10 million tons of CO 2 for the Hakodate Bay area to 4.2 billion tons of CO 2 for the Osaka Bay area, although the quantitative significance of these assessments must be considered to be only preliminary.

Combining geologic data and numerical modeling to improve estimates of the CO2 sequestration potential of the Rock Springs Uplift, Wyoming

Abstract We present results from the first stages of a detailed three dimensional analysis of the geologic CO 2 sequestration potential of the Rock Springs Uplift (RSU), located in south-western Wyoming. This site is of particular interest because of the collocated 2.1 GW Jim Bridger coal burning power plant and the possibility of additional power plants being developed in the area to take advantage of the abundant coal reserves in the RSU region (i.e. the Southern California Edison CEPL project). The Rock Springs Uplift is a huge asymmetric dome structure with two superior target sequestration reservoirs located beneath a 1500 m thick sequence of Cretaceous shale. The target reservoirs, the Weber Sandstone and Madison Limestone, with thicknesses of greater than 200m and 75m respectively, are located at depths where pressures are well above the critical point of CO 2 . Seismic data reveal that the structure of the RSU creates an ideal trap for buoyant supercritical CO 2 . The target reservoirs currently contain high salinity sour brines (35,000-80,000 ppm) with little or no economic value. Reservoir continuity inferred from well logs and cores and high average measured porosity (10%) and permeability (10-75 md) led to initial screening estimates on the order of 26 billion tons of CO 2 for the storage capacity of the structure. This paper focuses on calculations that will help to refine the initial capacity estimates through the use of high resolution multiphase numerical models. First we present an analysis using a system level simulator, CO2-PENS, to differentiate between two injection depths in the Weber on the basis of the costs associated with on-site drilling and pipelines for a range of permeabilities. The deeper site is analogous to the subsurface near the Jim Bridger Power Plant (JBPP), while the shallower site is analogous to the crest of the RSU. Results of this analysis show that deeper injection may be more cost effective. Next, we develop a 3-D computational hydrostratigraphic model and simulate injection of CO 2 near the Jim Bridger Power Plant. Utilizing existing seismic and wellbore data, a geologic framework model has been created in EarthVision (i.e., 3D model building and visualization software). From this model, hydrostratigraphic units were extracted and a 3-D computational mesh for a 16×16 km section of the RSU structure was constructed. This model is used to simulate injection of 80% of the total CO 2 emissions from the 2.1 GW JBPP (483 kg/s or 15 Mt/year) into the Weber formation for two cases. The first case assumes a very high permeability in the Weber and needs only one injection well, while the second case assumes a lower permeability and uses 9 injection wells. The major differences between these two examples are the amount of CO 2 that dissolves into the formation brines and the areal extent of the resulting plumes. Because the low permeability case requires more injectors, the injected CO 2 is exposed to a larger volume of reservoir rock and leads to a higher percentage of the total injected CO 2 being dissolved in the formation water. The focused injection for the high permeability case leads to more CO 2 remaining in the supercritical state and longer up-dip transport. Finally, both cases show that both diffusive and advective transport into the surrounding strata may significantly increase the storage potential of the RSU.

Carbon storage in depleted gas fields: Key challenges

Abstract It is recognized that most of the available geological storage capacity for CO 2 is in saline aquifers. The best aquifers are likely to be in sedimentary basins (and in many cases near to fossil energy sources). However, unless the formations have been explored for hydrocarbon potential, it is likely that little data exists so significant work will be required to evaluate the realistic storage potential. Depleted gas fields offer more limited capacity but are better characterized, have seals that have successfully retained hydrocarbon gas for millions of years, and may offer a shorter route to practical implementation for early projects. Estimates indicate that depleted offshore gas fields in UK waters have the potential to store around 3.8 billion tonnes of CO 2 . This is a significant capacity and an inviting target particularly if existing infrastructure and wells can be reused. This paper explores the issues around injecting and storing CO 2 in highly depleted gas fields using a case study based on the characteristics of a Southern North Sea gas field. The study shows that assessing and managing the flow control aspects of CO 2 injection, particularly initially when the reservoirs are at very low pressure is going to be a major technical challenge. The challenges include a requirement for a high -tech flow control device at the base of the tubing to allow the dense phase CO 2 to be expanded in a controlled manner. Also the requirement for CO 2 -specific well flow performance software as conventional software, designed to model the flow of hydrocarbons, is not necessarily suffciently rigorous when modeling a complex fluid like CO 2 , particularly the thermodynamics aspects. Understanding and mitigating Joule Thomson effects is necessary to avoid the possible formation of ice and gas hydrates. Without a comprehensive understanding of CO 2 flow systems and accurate modeling of the thermodynamic effects it may not be possible to realize the potential that gas field storage offers.

CO2 point emission and geological storage capacity in China

Abstract Carbon dioxide capture and geological storage (CCS) is regarded as an effective option to reduce CO 2 emissions from the use of fossil fuels. CCS is particularly important to China due to its large and rapidly rising emissions and high dependence on fossil fuel, and large remaining coal reserves. This paper presents the key results of the authors’ study to evaluate o pportunities for the deployment of CCS technologies within China. It focuses on the data, methodology, and results of basin-scale CO 2 sto rage capacity and CO 2 point emission estimation in China. There is a total estimated theoretical CO 2 geological storage capacity of 3088 gigat ons in China’s onshore and offshore basins, including a storage capacity of 3066 gigatons for deep saline formations accounting for 99% of total geological storage resource. China also has an annual emission about 3.9 billion tons of CO 2 from large point sources in 2007. In view of initial site-source matching analysis, He huai Basin, Bohai Bay Basin, Subei Basin and Sichuan Basin have the best potential for CCS deployment. There is significant potential for CCS technologies to deliver deep, sustained and cost-effective emissions reductions for China over the course of this century

Taking out 1 billion tons of CO 2: The magic of China's 11th Five-Year Plan?

China's 11th Five-Year Plan (FYP) sets an ambitious target for energy-efficiency improvement: energy intensity of the country's gross domestic product (GDP) should be reduced by 20% from 2005 to 2010 [National Development and Reform Commission (NDRC), 2006. Overview of the 11th Five Year Plan for National Economic and Social Development. NDRC, Beijing]. This is the first time that a quantitative and binding target has been set for energy efficiency, and signals a major shift in China's strategic thinking about its long-term economic and energy development. The 20% energy-intensity target also translates into an annual reduction of over 1.5 billion tons of CO 2 by 2010, making the Chinese effort one of the most significant carbon mitigation efforts in the world today. While it is still too early to tell whether China will achieve this target, this paper attempts to understand the trend in energy intensity in China and to explore a variety of options toward meeting the 20% target using a detailed end-use energy model.

Carbon Capture & Storage: Blue-Sky Technology or Just Blowing Smoke?

Towering 650 feet over the sea surface and spouting an impressive burning flare, it would be easy to mistake the Sleipner West gas platform for an environmental nightmare. Its eight-story upper deck houses 200 workers and supports drilling equipment weighing 40,000 tons. Located off the Norwegian coast, it ranks among Europe’s largest natural gas producers, delivering more than 12 billion cubic feet of the fuel annually to onshore terminals by pipeline. Roughly 9% of the natural gas extracted here is carbon dioxide (CO2), the main culprit behind global warming. But far from a nightmare, Sleipner West is actually a bellwether for environmental innovation. Since 1996, the plant’s operators have stripped CO2 out of the gas on-site and buried it 3,000 feet below the sea floor, where they anticipate it will remain for at least 10,000 years. We believe [CCS] is a viable way to cut global warming pollution. . . . We have the knowledge we need to start moving forward. –David Hawkins, Natural Resources Defense Council Operated by StatoilHydro, Norway’s largest company, Sleipner is among the few commercial-scale facilities in the world today that capture and bury CO2 underground. Many experts believe this practice, dubbed carbon capture and storage (sometimes known as carbon capture and sequestration, but in either case abbreviated CCS), could be crucial for keeping industrial CO2 emissions out of the atmosphere. Sleipner injects 1 million tons of CO2 annually into the Utsira Formation, a saline aquifer big enough to store 600 years’ worth of emissions from all European power plants, company representatives say. With mounting evidence of climate change—and predictions that fossil fuels could supply 80% of global energy needs indefinitely—the spotlight on CCS is shining as brightly as the Sleipner flare. A panel of experts from the Massachusetts Institute of Technology (MIT) recently concluded that CCS is “the critical enabling technology to reduce CO2 emissions significantly while allowing fossil fuels to meet growing energy needs.” The panel’s views were presented in The Future of Coal, a report issued by MIT on 14 March 2007. Environmental groups are split on the issue. Speaking for the Natural Resources Defense Council (NRDC), David Hawkins, director of the council’s Climate Center and a member of the MIT panel’s external advisory committee, says, “We believe [CCS] is a viable way to cut global warming pollution. . . . We have the knowledge we need to start moving forward.” Other environmental groups, including the World Resources Institute, Environmental Defense, and the Pew Center on Global Climate Change, have also come out in support of CCS. These groups view CCS as one among many alternatives (including renewable energy) for reducing CO2 emissions. Greenpeace is perhaps the most vocal critic of CCS. Truls Gulowsen, Greenpeace’s Nordic climate campaigner, stresses that CCS deflects attention from renewable energy and efficiency improvements, which, he says, offer the best solutions to the problem of global warming. “Companies are doing a lot of talking about CCS, but they’re doing little to actually put it into place,” he says. “So, they’re talking about a possible solution that they don’t really want to implement now, and at the same time, they’re trying to push for more coal, oil, and gas development instead of renewables, which we already know can deliver climate benefits.”

A Global Land Use and Biomass Approach to Reduce Greenhouse Gas Emissions, Fossil Fuel Use and to Preserve Biodiversity

As average growth consumptions per capita and world population will continue to grow, the promotion of sustainable developments during the next half a century implies to take into account environmental aspects, local potentialities and futures changes in population as well climatic, economic and social factors. At the global level, land and fossil fuel availability per capita, capacity of absorption of greenhouse gas emissions are considered the most important environmental factors. Whereas at local levels are to be considered preservation or improvement of soil fertility, of water regimes, of quality of air, soil and water. Biodiversity must be taken into account at both levels to cope also with climate change. But as underlined by IPCC lead authors, up to now there is no tool available to deal with these issues in a comprehensive and adequate manner. A new tool, presented here, the Integrated Environmental Assessment (IEA) has therefore been developed. It takes into account all actions, from the sun to final services, in three stages: solar energy bioconversion and phytomass production at I; conversion of phytomass and non renewable resources into final products and waste disposal at II; arrangement of products to meet final needs, such as nutrition, housing mobility etc. at III. IEAs start at the global level with the GIEA, the results of which are then to be confronted with constraints at local levels from LIEAs. This new tool can be used to identify impacts of technological changes in land management and to compare alternative practices better than with LCAs. It was used to analyze environmental impacts of technological changes between 1950 and 2000 in France, in wheat production at stage I. It appeared that not only yields, but also the primary mitigation potential (PMP) per hectare have been multiplied by 4, whereas the net primary energy gain per ha has been multiplied by 3.2. Besides this, 14,5 Mha (the area of the French forest about a quarter of France) land use change could be avoided; in the case of deforestation this would have led to the emission of more than 4 billion tons of CO2. Lessons are drawn from the past and for the next fifty years: In developed and industrialized countries, alternative managements of land and increased use of non food phytomass can and should be envisaged. In Sub-Saharan Africa population is expected to double during the next 50 years and soil fertility is drastically decreasing; agricultural practices are no longer sustainable. If no changes appear in agriculture, forests and GHG emission from deforestation as well as biodiversity are threatened by further and inevitable land use change. Increasing yields per hectare should therefore become the priority; it would at the same time increase food security, improve mitigation and adaptation to climate change, help to combat deforestation and desertification, better preserve biodiversity, and ultimately also allow more bioenergy production: This would improve the food security and at the same time help to achieve the objectives of the three main UN environmental conventions and of the UN Millennium Goal.

Nuclear energy: current situation and prospects to 2020

For close to half a century nuclear fission has been providing reliable supplies of electricity to the UK, with virtually no emissions of carbon dioxide. Over that period, the UK nuclear industry has avoided the emission of over one and a half billion tonnes of CO2. Yet no nuclear plant has been built in the UK for over two decades even though many of the stations in our current fleet are now within a decade or so of the end of their lifetime. Without new plants being ordered soon, the UK's nuclear capacity will decline dramatically, from 23% today to 3% post-2020--just as considerations of supply security and climate change are becoming increasingly important. Elsewhere in the world, many countries such as China, India, Japan, South Korea, Finland and France are building new stations. Other countries such as the USA, South Africa, and some nations that currently do not have nuclear stations (such as Indonesia and Poland) are making preparations for future nuclear stations. Globally capacity factors for nuclear plants are higher than they have ever been, averaging around 85% and with the best stations achieving well over 90%. Lifetime can be 60 years. That the economics of such stations compete well with other technologies is well founded and easily verifiable--especially in the face of rising fossil fuel prices and the pricing in of costs for CO2 emissions--both of which stand to improve the economics of nuclear energy still further. Waste volumes arising from modern plants are just a fraction of those of some earlier stations, and the technologies are in place to deal with them safely and effectively. Following recent reviews and international developments, there is growing confidence that internationally available competitive designs of nuclear plant will provide part of the solution to the UK's long-term energy needs.

Growth of fluoroform (CHF3, HFC‐23) in the background atmosphere

There is growing concern over the emission and accumulation of very long‐lived fluorinated trace gases in the atmosphere, due to their large global warming potentials (GWPs). Unlike CFCs and other ozone‐depleting, chlorinated and brominated chemicals, consumption of these fluorinated compounds is not controlled by the Montreal Protocol or any other international agreement. Of all the known and potential trace ‘greenhouse’ gases, the two with the highest GWPs are sulfur hexafluoride (SF6) and fluoroform (CHF3, HFC‐23). Whereas several studies have reported the detection and accumulation of SF6 in the atmosphere, the presence of HFC‐23 has remained unreported. We have found that present‐day HFC‐23 concentrations (c. 11 pptv in late 1995) exceed those of SF6 by a factor of three. Concentrations have steadily increased in the atmosphere since at least 1978, and are continuing to do so at a present rate of 5% per year. Furthermore, HFC‐23 appears to be long‐lived in the atmosphere, with a stratospheric lifetime of at least 1000 years, and a modelled tropospheric lifetime of 230 years. In terms of global warming, the cumulative emissions of HFC‐23 up to, and including, 1995 are equivalent to 1.6 billion tonnes of CO2.

Possibility of underground CO 2 sequestration in Japan

The possibility of underground CO 2 sequestration in depleted oil and gas fields and aquifers is being studied in Japan. The underground structures in the study are classified into four categories, as follows. 1. Category 1: Oil and gas reservoirs and neighboring aquifers. 2. Category 2: Aquifers in anticlinal structures. 3. Category 3: Aquifers in monoclinal structures on land. 4. Category 4: Aquifers in monoclinal structures offshore. The potential is computed at the volume of three billion tonnes of CO 2 by summation of categories 1) and 2). The estimated potential is about eighty billion tonnes of CO 2 by summation of categories 3) and 4).

The 1982-1983 El Niño: a 6 billion ton CO2release

The atmospheric CO 2 concentration at Amsterdam Island showed important variations of the increase rate during the 1982-1983 El Nino. After elimination of the weak local and regional interferences, the main feature of the CO 2 record is a slower than normal increase rate at the beginning and at the end of this El Nino, i.e., from April to December 1982, and from July 1983 to April 1984. and higher than usual from December 1982 to July 1983. In the whole, the CO 2 increase curve is shifted upwards by 1 ppm, which corresponds to a supplementary input into the atmosphere of about 6 billion tons of CO 2 . DOI: 10.1111/j.1600-0889.1987.tb00283.x