Specific Emission Reduction Research Articles

Taxing CO 2 and subsidising biomass: analysed in a macroeconomic and sectoral model

This paper analyses the combination of taxes and subsidies as an instrument to enable a reduction in CO 2 emission. The objective of the study is to compare recycling of a CO 2 tax revenue as a subsidy for biomass use as opposed to traditional recycling such as reduced income or corporate taxation. A model of Denmark’s energy supply sector is used to analyse the effect of a CO 2 tax combined with using the tax revenue for biomass subsidies. The energy supply model is linked to a macroeconomic model such that the macroeconomic consequences of tax policies can be analysed along with the consequences for specific sectors such as agriculture. Electricity and heat are produced at heat and power plants utilising fuels which minimise total fuel cost, while the authorities regulate capacity expansion technologies. The effect of fuel taxes and subsidies on fuels is very sensitive to the fuel substitution possibilities of the power plants and also to the extent to which expansion technologies have been regulated. It is shown how a relatively small CO 2 tax of 15 US$/tCO 2 and subsidies for biomass can produce significant shifts in the fuel input-mix, when the expansion of production capacity is regulated to ensure a flexible fuel mix. The main finding is that recycling to biomass use will reduce the level of CO 2 tax necessary to achieve a specific emission reduction. Policies to ensure a more intensive use of such relatively expensive renewable energy sources as biomass could be implemented with only small taxes and subsidies.

Shift Reactors and Physical Absorption for Low-CO2 Emission IGCCs

Integrated gasification combined cycles (IGCC) exhibit conditions particularly favourable to the sequestration of CO2. The concept pursued in this paper is the generation of syngas low in carbon, where most of the heating value of the coal fuel is carried by hydrogen. Catalytic shift reactors convert most of the CO in the syngas into CO2, which is subsequently removed by physical absorption and then compressed to make it suitable for transport and permanent storage. Energy balances, performance, and cost of electricity are evaluated for two plants based on a Texaco gasifier and a large, heavy-duty gas turbine giving an overall IGCC power output between 350 and 400 MW. In one plant, the raw syngas exiting the gasifier is cooled in a high-temperature, radiative cooler; in the other it is quenched by the injection of liquid water. With respect to “conventional” Texaco IGCCs, the reduction of specific CO2 emissions by 90 percent reduces LHV efficiency from 5 to 7 percentage points and increases the cost of electricity of about 40 percent. These penalties can be reduced by accepting lower reductions of CO2 emissions. Compared to the semiclosed cycle considered by other authors, where CO2 is the main component of the gas turbine working fluid, the plants analyzed here exhibit higher efficiency over the whole range of specific CO2 emissions.

Joint Implementation and Forestry Projects: Conceptual and Operational Fallacies

Increased human activity is causing a build-up of greenhouse gases (GHGs) which are thought to contribute to global warming. Climate change is an international environmental concern because the effects of GHG emissions will be felt throughout the world irrespective of their origin.Similarly,mitigation activities undertaken anywhere in the world have the same impact on the global environment. The Framework Convention on Climate Change, opened for signature in June 1992 during the Rio conference, seeks to address the problem of global warming at the international level. It has received widespread acceptance and has been ratified by 171 states.While the convention does not set out specific emission reduction targets,the recently adopted Kyoto Protocol sets out quantified emission limitation and reduction commitments for OECD countries and countries undergoing the process of economic transition to a market economy (Annex B parties).Annex B parties commit themselves to reduce their overall GHG emissions by at least 5 per cent below 1990 levels between 2008 and 2012.1 Developing countries do not take on emission limitation or reduction commitments. In the first part of this article,we analyse the mechanism of joint implementation (JI) generally and in the Climate Change Convention specifically.The second part concentrates on JI projects in the forestry sector.We argue that the carbon sequestration potential of trees on which JI forestry projects are predicated has not been proven.Indeed,in the long term,these projects have a very limited effect on carbon sequestration considering that woody biomass eventually decays or burns.We also argue that JI forestry projects often conflict with local and international environmental priorities.The third part addresses concerns with JI at the international level.It focuses on reordering JI priorities and fitting development concerns in JI.

Effectiveness of non-CO2 greenhouse gas emission reduction technologies

Non-CO2 greenhouse gases, such as methane and nitrous oxide, can make a relevant contribution to the enhanced greenhouse effect, and hence emission reduction is desirable. In emission reduction inventories, both the magnitude of the emission reduction as well as the specific emission reduction costs should be determined. The current knowledge of the potential for and costs of reducing these emissions is still limited. Taking this into account, the following results can be obtained. Methane emissions can be considerably reduced from underground coal mining, oil production, natural gas operations, landfilling of waste, and wastewater treatment. Also emissions from enteric fermentation and animal manure can be reduced substantially. The total technical potential for methane emission reduction (given the present activity level) is estimated to be about one third. The economic potential, having net negative emission reduction costs, is estimated to be about half of this value. These reductions can be attained over a period of 10 - 20 years. The technical potential for the reduction of nitrous oxide emissions is currently estimated to be less than 10% Apart from the possibility of implementing existing techniques, there seems to be considerable room for developing techniques for more far-reaching emission reductions both for methane and nitrous oxide.

Carbon dioxide recovery using a dual gas turbine IGCC plant

A new scheme is described for electricity production based on coal gasificiation with recovery of CO 2. Coal is gasified into a synthesis gas, mainly consisting of hydrogen and carbon monoxide. After clean-up, this synthesis gas is separated by a membrane into a carbon-rich gas and a hydrogen-rich gas. The hydrogen-rich gas is fed to a conventional gas turbine. The carbon-rich gas is fed to another gas turbine, where it is fired in a mixture of oxygen and CO 2. The exhaust of the latter is almost pure CO 2 and can be stored outside the atmosphere. The CO 2 emissions of this plant are about 10% of the emissions of an IGCC plant without CO 2 recovery, and the conversion efficiency is approx. 6% lower. A first estimate is that the electricity production costs are about one third higher. It is found that the specific emission reduction costs can be limited to about $16 per tonne of CO 2 avoided. The main technical problem of this new scheme is the development of a new type of gas turbine with CO 2 as working fluid.