Limits to the potential of bio-fuels and bio-sequestration of carbon

This document examines bio-physical limits of bio-fuels and bio-sequestration of carbon by examining available solar radiation and observed efficiencies with which natural ecosystems and agricultural systems convert that energy to biomass. It compares these energy/carbon exchanges with national levels of energy use and carbon emissions for Australia, Brazil, China, Japan, Republic of Korea, New Zealand, Papua New Guinea, Singapore, Sweden, United Kingdom and United States.Globally primary energy consumption (related carbon emissions) is currently equivalent to ~0.06% of the incident solar energy, and 43% of the energy (carbon) captured by photosynthesis.The nations fall into three categories. Those with primary energy consumption that is: 1–10% (Japan, Korea and Singapore); ~0.1% (China, UK and the US) and; 0.1–0.01% (Australia, Brazil, Papua New Guinea, New Zealand and Sweden) of incident solar radiation. The percentage of energy captured in biomass follows this pattern, but generally lower by ~3 orders of magnitude.The energy content of traded wheat, corn and rice represents conversion efficiencies of solar radiation of 0.08–0.17% and for sugar close to 1%, ignoring energy use in production and conversion of biomass to fuels.The study implies that bio-fuels or bio-sequestration can only be a small part of an inclusive portfolio of actions towards a low carbon future and minimised net emissions of carbon to the atmosphere.     

Biomass: A modern and environmentally acceptable fuel

The energy of the sun and carbon dioxide from the atmosphere are captured by plants during photosynthesis. Plant biomass can be used to absorb carbon dioxide emissions from fossil fuels, or it can be converted into modern energy carriers such as electricity, and liquid and gaseous fuels. Biomass supplies 13% of the world's energy consumption (55 EJ, 1990), and in some developing countries it accounts for over 90% of energy use. There is considerable potential for the modernisation of biomass fuels through improved utilisation of existing resources, higher plant productivities and efficient conversion processes using advanced technologies. The interest in bioenergy is increasing rapidly, and it is widely considered as one of the main renewable energy resources of the future due to its large potential, economic viability, and various social and environmental benefits. In particular, biomass energy is among the most favourable options for reducing carbon dioxide emissions. Most of the perceived problems such as land availability, environmental impact, economic viability, and efficiency can be overcome with good management. The constraints to achieving environmentally-acceptable biomass production are not insurmountable, but should rather be seen as scientific and entrepreneurial opportunities which will yield numerous advantages at local, national and international levels in the long term.     

The study on the carbon dioxide sequestration by applying wooden structure on eco-technological and leisure facilities

Because the photosynthesis ability of old artificial forest stands is inferior to that of young stands, the utilization of these logs is benefit to the sequestration of carbon dioxide. Hence, construction of wooden patios, trails, and retaining wall to substitute concrete ones could reduce the carbon dioxide emission in Taiwan. According the research data, the energy consumption during wood processing was very low, so did the carbon dioxide emission. Because concrete was replaced and about 50% of wood consists of carbon which is from carbon dioxide sequestration, both the utilization of wood and artificial forest planted could reduce the carbon dioxide concentration. The purpose of the study was to evaluate the effects of carbon dioxide emission and sequestration by using wooden structure in both wooden leisure and eco-technological facilities. Results shown when check dam constructed by ACQ treated Japanese cedar following O&D (outdoor) method and CNS3000 K4 criterion with 40 years lifetime could reduce about 30 tons of carbon dioxide emission, which is equivalent to the carbon dioxide expiration of 92 persons per year. On another case, 61 tons of carbon dioxide emission was reduced, which is equivalent to the carbon dioxide expiration of 190 persons per year. If the high energy consumption materials, such as steel and cement, could be substituted by wood or wooden material, it could be beneficial to the sustainable management of the earth environment.     

Carbon dioxide and climate : Too much heat clouds debate

A growing awareness of the possibility of a carbon dioxide ‘greenhouse effect’ acting to warm the Earth unpleasantly has been seized on in some quarters as an argument against increased use of fossil fuels and, by implication, in support of a massive nuclear programme. These issues need to be set in a proper climatological perspective, comparing the possible extent of anthropogenic influences on climate with natural fluctuations, and should also take some account of mankind's technological capability to cope with the problem, once carbon dioxide has been recognized as a ‘pollutant’. Such a viewpoint shows that while the carbon dioxide problem is real and has important implications for energy policy, neither the problem nor the policy implications are the same as those pressed upon us by the fossil fuel doomsters.     

In-situ mineralization of carbon dioxide in a coal-fired power plant

Mitigation of anthropogenic carbon dioxide is needed in order to allow societies to maintain the existing carbon-based infrastructure, while minimizing the effects of carbon dioxide (CO₂) on the earth eco-system. A system that consists of pressure swing adsorption and in-situ mineralization unit was introduced to capture carbon dioxide (CO₂) from a 700 MW pulverized coal-fired power plant. Results from the work demonstrate that pressure swing adsorption for post-combustion carbon capture consumed the least energy, followed by biomass co-firing, pre-combustion cryogenic-membrane hybrid, and post-combustion monoethanolamine absorption. For carbon capture and sequestration, the pressure swing adsorption-fixation system was found to yield the lowest environmental burden factor, followed by off-site sequestration in deep sea and depleted underground oil/gas fields.     

Making carbon dioxide sequestration feasible: Toward federal regulation of CO2 sequestration pipelines

As the United States moves closer to a national climate change policy, it will have to focus on a variety of factors affecting the manner in which the country moves toward a future with a substantially lower carbon footprint. In addition to encouraging renewable energy, smart grid, clean fuels and other technologies, the United States will need to make substantial infrastructure investments in a variety of industries. Among the significant contributors to the current carbon footprint in the United States is the use of coal as a major fuel for the generation of electricity. One of the most important technologies that the United States can employ to reduce its carbon footprint is to sequester the carbon dioxide (“CO₂”) from coal-fired power plants. This article focuses on the legal and policy issues surrounding a critical piece of the necessary sequestration infrastructure: CO₂ pipelines that will carry CO₂ from where it is removed from fuel or waste gas streams to where it will be sequestered. Ultimately, this article recommends developing a federally regulated CO₂ pipeline program to foster the implementation of carbon sequestration technology.     

Analysis of biomass co-firing systems in Taiwan power markets using linear complementarity models

Biomass co-firing systems in power plants generate electric power by the simultaneous combustion of biomass and fossil fuels. The co-firing process reduces investment costs by converting biomass energy into electricity in existing conventional power plants. Biomass co-firing significantly reduces carbon dioxide and sulfur dioxide emissions in power generation. To meet the increase in biomass demand, this paper has considered systematic energy crop production, which is expected to increase in the near future. Our aim is to analyze biomass co-firing systems in the Taiwanese electricity market. In this paper, we study two emerging biomass feedstocks: switchgrass and Miscanthus. We focus on the impact of energy crop co-firing on carbon dioxide and sulfur dioxide emissions for electricity generation. A Nash–Cournot competition model, which simulates potential biomass co-firing scenarios, is formulated for power markets. A case study conducted in the Taiwanese electricity market showed that biomass co-firing lowers total electricity demand and sale. Miscanthus is more economical than switchgrass in terms of the production cost and the land required to generate biopower for the same levels of biomass co-firing.     

草比树大

草本植物与木本植物的固碳效率差异,其本质是C4植物与C3植物的光合效率差异。C4植物主要存在于草本植物中,光合作用启动快、光呼吸弱、CO2补偿点低、光合效率高;木本植物大多数是C3植物,光合作用启动慢、光呼吸强、CO2补偿点高、光合效率低。在经度、纬度、时间、空间和面积相同的种植条件下,通过实验田选育的O4草本植物叶片总面积、叶绿体总数量、生物质总量、碳吸收总量、热吸收总量和氧释放总量均大于O3木本植物。本研究证明了O4草本植物是生态文明建设和应对全球气候变暖的先锋植物。将植物吸收CO2和热量、释放O2后形成的生物质应用到新气候经济的产业链中,替代化石燃料发电,进行“应用封碳”、“使用封碳”、“成型封碳”与“填埋封碳”,为碳热氧交易提供了实物产品,可产生巨大的“暂时碳汇量”、“长期碳汇量”和“永久碳汇量”。通过实体碳热氧产品交易,推行碳热氧税制度,创建零碳模式,可调节由温室气体造成的全球气候变暖。     

Biochar as a viable carbon sequestration option: Global and Canadian perspective

Biochar production and mixing in soil are seen as the best options for atmospheric carbon sequestration, providing simultaneous benefits to soil and opportunities for distributed energy generation. The proximity of biomass source and biochar dispersal greatly reduces the energy and emissions footprint of the whole process. The viability of the whole biochar process is examined from two boundary points: is there enough biomass around to have significant impact on the atmospheric CO₂ levels and is there enough soil area for biochar dispersal. The answers are soundly positive, both for the world as a whole and for Canada, for which a more detailed analysis was done. However, the massive adoption of biochar solution is critically dependent on proper recognition of its carbon sequestration impact its soil improvement potentials. To that extent the International Biochar Initiative, together with national chapters, including recently formed Canadian Biochar Initiative, are actively promoting biochar related research and policy framework. This paper addresses the questions of availability of sources and sites that would benefit from its dispersal.     

Carbon dioxide (CO2) storage and sequestration of land cover in the Leyte Geothermal Reservation

This study estimated the existing stored carbon (C) and rate of sequestration by vegetation that can potentially serve as a sink for the carbon dioxide emitted from eight geothermal plants in Leyte Geothermal Reservation, Philippines. For the 20,438 ha watershed in the vicinity of the power project, the total C storage is 3.84 Mt C (14.10 Mt CO₂) while C sequestration based on biomass change was 47.35 kt C (173.77 kt CO₂). Relative to power plant emission, the C stored in the reserve is equivalent to more than 22 years of CO₂ emission. Annual C sequestration is 27% of CO₂ emission per year. For the next 25 years, two scenarios were projected. Under Scenario I (“Business as Usual”), the forest reserve will be able to store and sequester more than 32 years of CO₂ emission from the power plants. Under Scenario II (“Accelerated Reforestation”), the reserve will be able to store and sequester about 34 years of CO₂ emission.In addition, the rate of C sequestration based on biomass change in vegetation was recorded to assess the optimum land use that can absorb the carbon dioxide emitted by the power project. These are as follows: tree plantations (10.09 tC/ha/yr)>coconut (4.78 tC/ha/yr)>brushland (4.29 tC/ha/yr)>natural forest (0.92 tC/ha/yr).In terms of cost, the power project operator is spending P1.22 per t CO₂ (P4.4 or US$0.12 per tC) for every year of C storage and sequestration. For 25 years, the total cost is P30.40 per tCO₂ (P111.5 or US$2.94 per tC) which is comparable to the cost of C offset in other tropical countries.     

Carbon charges and natural gas use in China

Substitution of natural gas for coal in China's power sector could significantly reduce emissions of carbon dioxide, but gas-fired power is generally more costly than coal-fired power in China today. This paper explores how carbon charges and carbon sequestration technology might tip the balance in favour of gas. The costs of electricity from new coal-fired and gas-fired power plants in China are compared under various assumptions about fuel costs, exchange rates, carbon dioxide charges, and application of carbon sequestration technology. Under average cost conditions today, gas-fired power is roughly two-thirds more costly than coal-fired power. But with a charge of $20/tonne of carbon dioxide, the costs of gas- and coal-fired power would typically be about equal. Over the longer term, carbon sequestration technology could be economical with a carbon dioxide charge of $22/tonne or more under typical cost conditions, but gas with sequestration would not have a clear cost advantage over coal with sequestration unless the charge exceeded $35/tonne.     

Economics of co-firing coal and biomass: An application to Western Canada

Co-firing biomass and coal in retrofitted power plants is an efficient means to reduce carbon dioxide emissions in the energy sector. Under IPCC reporting rules, the impacts of energy produced from biomass would not be reported in the energy sector, thereby effectively lowering the emission intensity of a power plant. In this study, a carbon tax is compared to a feed-in tariff for incentivizing conversion of coal plants to co-fire with biomass. In the application, a model of the Alberta electrical grid with an intertie to British Columbia is linked to a fiber transportation model for these provinces. Results indicate that there is an upper threshold on a carbon tax after which retrofitting of coal plants is less efficient than increasing natural gas generating capacity. This is not the case with a feed-in tariff as it specifically targets biomass energy. Although the optimal generating mix achieved with a carbon tax leads to lower aggregate emissions than the mix achieved using a feed-in tariff, it will result in higher average generating costs. Results indicate that it is optimal for Alberta to retrofit approximately 500 MW of current coal capacity (8.6%) to co-fire with biomass, although Alberta wood pellet production acts as a constraint on further conversions.     

Black carbon sequestration as an alternative to bioenergy

Most policy and much research concerning the application of biomass to reduce global warming gas emissions has concentrated either on increasing the Earth's reservoir of biomass or on substituting biomass for fossil fuels, with or without CO₂ sequestration. Suggested approaches entail varied risks of impermanence, delay, high costs, and unknowable side-effects. An under-researched alternative approach is to extract from biomass black (elemental) carbon, which can be permanently sequestered as mineral geomass and may be relatively advantageous in terms of those risks. This paper reviews salient features of black carbon sequestration and uses a high-level quantitative model to compare the approach with the alternative use of biomass to displace fossil fuels. Black carbon has been demonstrated to produce significant benefits when sequestered in agricultural soil, apparently without bad side-effects. Black carbon sequestration appears to be more efficient in general than energy generation, in terms of atmospheric carbon saved per unit of biomass; an exception is where biomass can efficiently displace coal-fired generation. Black carbon sequestration can reasonably be expected to be relatively quick and cheap to apply due to its short value chain and known technology. However, the model is sensitive to several input variables, whose values depend heavily on local conditions. Because characteristics of black carbon sequestration are only known from limited geographical contexts, its worldwide potential will not be known without multiple streams of research, replicated in other contexts.     

Use of near-infrared radiation for oxygenic photosynthesis via photon up-conversion

Radiation between 400 and 700 nm, used for oxygenic photosynthesis by cyanobacteria, algae and plants, represents only 44% of total solar energy while the range above 700 nm comprises 52%. An ability to use near infrared (NIR, 700–1200 nm) radiation would greatly improve the efficiency of photosynthesis, but NIR photons have too low energy to excite the photosystems of oxygenic photosynthesis. Here we show that a mechanism called photon up-conversion can turn NIR radiation into an energy source for photosynthesis. In the future, it may be possible to up-convert the NIR part of the solar energy flux to visible light for use in photo-induced biohydrogen production by oxygenic photosynthesis.     

International policy issues regarding solar water heating, with a focus on New Zealand

Like many countries New Zealand is moving towards renewable energy targets and has recently (November 2006) announced a revised solar hot water heating subsidy program that is being implemented through the Energy Efficiency and Conservation Authority (EECA). This paper describes the new program and reviews international policies regarding solar water heating to see which aspects have been effective in gaining an increased penetration of solar systems for water heating. In addition, the factors leading to successful policy implementation and the possible downsides of the 2006 New Zealand policy are discussed with regard to international experience.     

Economic efficiency of solar hot water policy in New Zealand

New Zealand has recently followed the path of several other countries in promoting solar hot water (SHW) systems in the effort to reduce greenhouse gas emissions, yet the economic efficiency of large-scale policies to encourage SHW remains a pressing question for policymakers. This paper develops an economic framework to examine policies to promote SHW in New Zealand, including the current information, training, and subsidy policy. The economic framework points to environmental, energy security, and average-cost electricity retail pricing market failures as motivation for SHW policy, with the global climate change externality the most important of these. The results indicate that domestic SHW systems are close to being financially attractive from a consumer perspective, but a more substantial subsidy policy would be necessary for SHW to appeal to a wider audience. Such a policy is far more likely to have positive net benefits than a policy of mandating SHW on all homes or all new homes in New Zealand, and could be justified on economic efficiency grounds under reasonable assumptions. However, this result reverses under an economy-wide carbon trading system that internalizes the environmental externality.     

Cost of energy and environmental policy in Portuguese CO2 abatement—scenario analysis to 2020

This paper quantifies the contribution of Portuguese energy policies for total and marginal abatement costs (MAC) for CO₂ emissions for 2020. The TIMES_PT optimisation model was used to derive MAC curves from a set of policy scenarios including one or more of the following policies: ban on nuclear power; ban on new coal power plants without carbon sequestration and storage; incentives to natural gas power plants; and a cap on biomass use. The different MAC shows the policies’ effects in the potential for CO₂ abatement. In 2020, in the most encompassing policy scenario, with all current and planned policies, is possible to abate only up to +35% of 1990 emissions at a cost below 23 € t/CO₂. In the more flexible policy scenarios, it is possible to abate up to −10% of 1990 emissions below the same cost. The total energy system costs are 10–13% higher if all policies are implemented—76 to 101 B€—roughly the equivalent to 2.01–2.65% of the 2005 GDP. Thus, from a CO₂ emission mitigation perspective, the existing policies introduce significant inefficiencies, possibly related to other policy goals. The ban on nuclear power is the instrument that has the most significant effect in MAC.     

Material constraints related to storage of future European renewable electricity surpluses with CO2 methanation

The main challenges associated with a growing production of renewable electricity are intermittency and dispersion. Intermittency generates spikes in production, which need to be curtailed when exceeding consumption. Dispersion means electricity has to be transported over long distances between production and consumption sites. In the Directive 2009/28/EC, the European Commission recommends sustainable and effective measures to prevent curtailments and facilitate transportation of renewable electricity. This article explores the material constraints of storing and transporting surplus renewable electricity by conversion into synthetic methane. Europe is considered for its mix of energy technologies, data availability and multiple energy pathways to 2050. Results show that the requirements for key materials and land remain relatively low, respecting the recommendations of the EU Commission. By 2050, more than 6 million tons of carbon dioxide might be transformed into methane annually within the EU. The efficiency of renewable power methane production is also compared to the natural process of converting solar into chemical energy (i.e. photosynthesis), both capturing and reenergizing carbon dioxide. Overall, the production of renewable methane (including carbon dioxide capture) is more efficient and less material intensive than the production of biofuels derived from photosynthesis and biomass conversion.     

Ocean carbon sinks and international climate policy

Terrestrial vegetation sinks have entered the Kyoto Protocol as offsets for anthropogenic greenhouse gas emissions, but ocean sinks have escaped attention. Ocean sinks are as unexplored and uncertain as were the terrestrial sinks at the time of negotiation of the Kyoto Protocol. It is not unlikely that certain countries will advocate the inclusion of ocean carbon sinks to reduce their emission reduction obligations in post-2012 negotiations. We use a simple model of the international market for carbon dioxide emissions to evaluate who would gain or loose from allowing for ocean carbon sinks. Our analysis is restricted to information on anthropogenic carbon sequestration within the exclusive economic zone of a country. We use information on the actual carbon flux and derive the human-induced uptake for the period from 1990 onwards. Like the carbon sequestration of business as usual forest management activities, natural ocean carbon sequestration applies at zero costs. The total amount of anthropogenic ocean carbon sequestration is large, also in the exclusive economic zones. As a consequence, it substantially alters the costs of emission reduction for most countries. Countries such as Australia, Denmark, France, Iceland, New Zealand, Norway and Portugal would gain substantially, and a large number of countries would benefit too. Current net exporters of carbon permits, particularly Russia, would gain less and oppose the inclusion of ocean carbon sinks.     

Geothermal energy technology and current status: an overview

Geothermal energy is the energy contained as heat in the Earth’s interior. This overview describes the internal structure of the Earth together with the heat transfer mechanisms inside mantle and crust. It also shows the location of geothermal fields on specific areas of the Earth. The Earth’s heat flow and geothermal gradient are defined, as well as the types of geothermal fields, the geologic environment of geothermal energy, and the methods of exploration for geothermal resources including drilling and resource assessment.Geothermal energy, as natural steam and hot water, has been exploited for decades to generate electricity, and both in space heating and industrial processes. The geothermal electrical installed capacity in the world is 7974 MW_e (year 2000), and the electrical energy generated is 49.3 billion kWh/year, representing 0.3 % of the world total electrical energy which was 15,342 billion kWh in 2000. In developing countries, where total installed electrical power is still low, geothermal energy can play a significant role: in the Philippines 21% of electricity comes from geothermal steam, 20% in El Salvador, 17% in Nicaragua, 10% in Costa Rica and 8% in Kenya. Electricity is produced with an efficiency of 10–17%. The geothermal kWh is generally cost-competitive with conventional sources of energy, in the range 2–10 UScents/kWh, and the geothermal electrical capacity installed in the world (1998) was 1/5 of that from biomass, but comparable with that from wind sources.The thermal capacity in non-electrical uses (greenhouses, aquaculture, district heating, industrial processes) is 15,14 MW_t (year 2000). Financial investments in geothermal electrical and non-electrical uses world-wide in the period 1973–1992 were estimated at about US$22,000 million. Present technology makes it possible to control the environmental impact of geothermal exploitation, and an effective and easily implemented policy to encourage geothermal energy development, and the abatement of carbon dioxide emissions would take advantage from the imposition of a carbon tax. The future use of geothermal energy from advanced technologies such as the exploitation of hot dry rock/hot wet rock systems, magma bodies and geopressured reservoirs, is briefly discussed. While the viability of hot dry rock technology has been proven, research and development are still necessary for the other two sources. A brief discussion on training of specialists, geothermal literature, on-line information, and geothermal associations concludes the review.