Biomass slurry (Coconut shell powder, diesel and water) combustion system considered in this problem is a simple cylindrical furnace of size 0.35m diameter by 0.56m height. The inlet to the furnace is at the bottom and the fuel enters the furnace in a sprayed form at 70m/s. Biomass slurry enters the furnace at the bottom with an average mass flow rate of 0.2m/s depending on the composition of the fuel. The furnace has a constant temperature of 12000C. The fuel supply to the furnace is from two tanks, one is the oil tank and the other is the slurry tank, compressed air connection is provided to the slurry tank to create pumping action whenever it is required. The outlets of both the pipes of the tanks

are connected to a single pipe at the nozzle. By controlling the valves, fuel supply to the burner can be had from anyone of the tanks. The burner used in the experimental setup consists of a central hole through which the liquid fuel or slurry flows. Operating the fuel valve at the base of the fuel tank controls the rate of flow of fuel from it. The atomization rate can be controlled using the needle valve. There are two airports, one for the primary air supply and the other for the secondary air supply. In the primary air supply line a continuous helical path is provided to create swirling of air. At the exit a nozzle is provided as shown in fig.1. The sudden expansion of air creates vacuum, which helps to draw the fuel from the fuel nozzle. Over the primary air passage, the secondary air passage is provided. The air enters tangentially to this passage. This has been provided in order to create further swirl. Operating the gates provided in the main entrance can control the quantity of air supply and the fuel supply.

2a. Finite Volume Modeling of the Furnace using Gambit

GAMBIT is a preprocessing software developed by Fluent inc, USA, the advantage of using GAMBIT is it has a single interface for geometry creation and meshing that brings together all of Fluent’s preprocessing technologies in one environment. Advanced tools for journaling let you edit and conveniently replay model building sessions for parametric studies.

FLUENT is the world leading CFD code for a wide range of flow modeling applications. With its long-standing reputation of being user-friendly, FLUENT makes it easy for new users to come up to productive speed. Its unique capabilities in an unstructured, finite volume based solver are near ideal in parallel performance.

Dimensions of the furnace Height of the furnace: 810mm

Outer Diameter of the furnace: 930mm Inner Diameter of the furnace: 570mm

For easy meshing the furnace was divided into three sections as shown in the following fig., because of the continuity in meshing the whole furnace though divided into three sections is considered has a single volume. For analysis purpose, the combustion chamber was modeled with different inlet conditions.

Model-II: Since in the Model-2a the inlet was exactly at 90deg., the solid

particles used to make a direct impact on the cylinder wall and come out of the furnace unburnt where in the residence time of the fuel was very small, so the inlet i. e. the nozzle position was inclined at various angles to get the optimum swirling of the fuel in the furnace as shown in the following analysis.

Inlet Inclination = 45 deg with respect to x and z axis Inlet diameter = 30 mm & 75 deg from positive y-axis, with top fully open The Cylinder was divided into 3 sections for easy meshing as shown below

MODEL-III: REFINED MODELING OF THE FURNACE WITH TOP PARTIALLY OPEN

Dimensions of the furnace I. Height of the furnace: 810mm

2.Outer Dia. of the furnace: 930mm 3.Inner Dia. of the furnace: 570mm 4.Inlet Dia. = 30mm

5.Outlet diameter = 140mm: Inclination of the inlet = 45 deg, with respect to x and z axis 75 deg from positive y — axis

For easy meshing the furnace was modeled as two separate sections as shown in the following fig., and was combined using t-merge for analysis.

For analysis purpose, the combustion chamber was modeled with different inlet conditions.

Fig.5a Bottom section of the combustion chamber with the inlet diameter=30mm Fig.5b Top section of the combustion chamber with the outlet 140mm

2. Results and discussions:

MODEL-I: With top fully open and the inlet angle of 45 degrees.

Material used to visualize the flow is Biomass and air, Inlet dia = 30mm and Outlet 570mm. For initialization: Inlet conditions: 700m/s; outlet condition =

Residence time of the fuel in the furnace = Total length of the path line

Velocity of the inlet fuel = nd(number of rounds)

700m/sec

= П(0.35)(1.5) = 0.002356sec’s 700

From the above velocity inlet path lines, static pressure, total pressure and velocity flow lines it has been concluded that the biomass particles used to not completely burn in the furnace after impact the solid particles used to impinge out of the furnace unburnt, since the top of the furnace was not closed, so the furnace was remodeled as shown in the following fig. With a small and the most optimum opening for the exhaust gases to escape out of the furnace.

MODEL-II: With top partially open and the inlet angle of 45 degrees.

For initialization:

Material — air Inlet conditions: 700m/s; outlet condition = 101325 Pa With material as Biomass volatiles with a density of 200 kg/m3 Inclination of the inlet = 45 deg w. r.t x and z axis 75 deg from positive y-axis

Residence time of the fuel in the furnace = Total length of the path line

Velocity of the inlet fuel = nd(number of rounds) 700m/sec

= П(0.35)(4) = 0.006283sec’s 700

From the above calculation of residence time of the fuel in the furnace it is clear that the residence time was increased from 0.002356sec’s to0.006283sec’s.

3. CONCLUSIONS:

From the study of the above path lines it has been concluded that the optimum circulation of the fuel has been obtained in the furnace and there is hardly any fuel escaping out of the furnace and complete combustion of the fuel is taking place inside the furnace because of the increase in the residence time of the fuel. With this result the efficiency of the furnace was increased from 25% to 65% and with these results 80W of power was generated and the same furnace was very easily used to melt Al of 4kgs/melt. Based on the above flow analysis and combustion analysis and on the same principles, analysis of combustion of Biomass slurry in I. C.engines can be done with at most ease.

Kindergarten, solar city, Linz:

One example of a recently implemented large scale solar installation is a kindergarten in Linz which features 40 m2 solar thermal and 100 m2 PV installations.

The Kindergarten is part of the new residential city district of Linz "solar city", were more than 4000 m2 solar thermal collectors have been installed.

Lenaupark Linz

A new residential area with the city centre is presently being built. The apartment buildings will be equipped with solar thermal and photovoltaic installations. So far more than 500 m2 solar thermal collectors have been installed.

Facade integrated solar installation

Another leading example of large scale solar installations is the largest solar thermal facade integrated installation at a multi-family house in Linz. In the course of retrofitting the building, a 240 m2 large solar thermal installation was integrated into the building’s facade and 120 m2 were mounted on the roof of the building. Hot water for the 126 flats is now provided by the sun.

Georgia is located at the meeting-point of Europe and Asia (41°07′- 43°35’N latitude and 40°05′- 46°44’E longitude), between the Black Sea and the Caspian lowland, on the southern slopes of the Caucasian Mountain Range. Its capital, Tbilisi, with a population of over 1 500 000 is located at 41 °47’N, 44°40’E.

Mt. Elbrus

Sukhumi

Despite Georgia’s relatively small area it possesses an impressive variety of geographical and climatic zones. In a relatively short distance you can move from subtropics to alpine
zones and from forests to sunny valleys or even semi-deserts. The climate of eastern Georgia is dry and continental with warm summers and moderate winters. Western Georgia, on the Black Sea coast, is marked by a warm and humid (subtropical) climate, with mild winters and comparatively hot summers.

1.1 Terrain

The terrain is largely mountainous with the Great Caucasus Mountains in the north and Lesser Caucasus Mountains in the south; the Colchida lowland opens to the Black Sea in the west, with the Mtkvari river basin in the east.

Lowest point: 0 m — Black Sea

Highest point: 5 201 m — Mt. Shkhara (on the border with Russia)

1.2 Climatic data for Tbilisi

Average annual temperature [35] Highest recorded temperature 1 Lowest recorded temperature 1 Average annual precipitation 1 Average wind speed 2 Annual total solar radiation [36] Number of sunny days 3 Annual average sunshine time 3 Ratio of actual sunshine time to maximum possible 3

O. Perpinan1p, A. Gonzalez1, J. Vega1,1. Eyras1, R. Eyras1

1ISOFOTON, S. A.,Montalban 9, 1° Dcha. 28014 Madrid, Spain, e-mail:
o. perpinan@isofoton. es

I. Introduction

From May to September 2004, the FORUM Barcelona 2004 will be celebrated in Barcelona, Spain. The Forum is a festive journey designed to bring the three main themes to life: cultural diversity, sustainable development and conditions for peace. For 141 days, this will be the place where millions of visitors experience cultures and entertainment from around the world through large and small scale exhibitions, workshops, markets, performances, games and more. 1

Several meetings, exhibitions, infrastructures and recommendations will be devoted to sustainable development as one of three axis of Forum. Among these infrastructures it should be highlighted a solar totem, a large photovoltaic pergola has been constructed as a monument to solar energy.

The original design is due to Spanish architects Martinez Lapena and Elias Torres. A huge structure composed by four legs of different height and slope supports a 3410 m2 photovoltaic generator. Maximum height of structure is 54 meters above sea level.

As a result of a public call for tender, the consortium FORUM SOLAR assumes the turnkey project. The consortium FORUM SOLAR is composed by: o ENDESA, utility private company. o IDOM, projects engineering company o INABeNsA, installation company.

o ISOFOTON, manufacturer and project engineering of PV systems.

F. Schmidhuber, C. Hebling Fraunhofer-Institute for Solar Energy Systems ISE Heidenhofstr. 2, 79110 Freiburg, Germany

Phone: +49 (0) 761/4588-5193, e-mail: helge. schmidhuber@ise. fraunhofer. de

Over 10 million Personal Digital Assistants (PDAs) and about 470 million cellular phones have been sold in the year 2003 ([Haines03], [Loding03]) and most of these devices use rechargeable batteries for the energy supply. The operation time of such devices can be increased if a solar module for charging the battery is integrated or if an external solar battery charger is used. With the today’s state of the art technology device integrated solar cells are interconnected either with tabs as in large standard modules, or they are contacted with the back on a printed circuit board (PCB). The front side contact is usually connected with a short tab on the plate. Partially the tabs are coloured black in order to give the solar module a uniform look. Contacting the solar cells to a PCB has the advantage that a mechanically very stable module is obtained. If one applies this interconnecting technology to high efficiency solar cells there is the disadvantage that by using the tabs the cell shading is increased. In this paper a novel method is presented, with which the shingle technology [Zhao97] and connection on a PCB are combined. One obtains an aesthetical, stable and nevertheless thin solar module, which is suitable for device integration.

A detailed description of the module concept is given and first measurements concerning the shingle technology, the connection and the encapsulation materials are shown. With the new module design it is possible to realise solar modules in a highly automated way with an efficiency between 18% and 20%.

Motivation

Today’s state of the art solar cells for device integration are interconnected either with small tabs as in large standard modules, or they are contacted with the back on a printed circuit board (PCB) and the front side contact is connected with a tab to the PCB. Partially the cell tabs are painted black, in order to give the solar module a uniform exterior. Contacting on a pCb has the advantage that depending upon choice of the PCB material a mechanically stable module is obtained and a packaging without a further backing material is possible. If the state of the art interconnecting technology is applied to high — efficient solar cells, it has the disadvantage that by the use of cell tabs the cell shading is increased.

The shingle technology for solar cells is described in [Zhao97] and [SCHMIDHUBER01a]. In this case the inactive cell part under the bus bar is covered by the active part of the next solar cell. The shading of the solar cells is reduced thereby and the module efficiency is increased.

In this paper a method is presented, in which the shingle technology and the interconnection on a PCB are combined. One receives an aesthetically looking, stable and nevertheless thin solar module, which is suitable for device integration. This new module concept is also very easy to produce because the finishing technology for surface mounted devices (SMD) can partially be used.

The first practical solar cells with vertical p-n-junctions were developed in Russia at the end of the sixties (there are British, German, and French Patents of Russian scientists) after considerable theoretical and experimental work in 1960th. The fist Russian invention was applied in 1967 (Strebkov D., Kozurev V.) Actually it is possible to tell: new class of silicon vertical multi-junction and high voltage cell technology were developed in 1967 (Landsman A., Strebkov D., Unishkov V. et al) [3-5].

In the early 1970s and later, in Russia a number of the new design ideas for high voltage SC for concentrated sunlight was put forward and realized [6].

The term multi-junctional edge-illuminated SC has been used in papers published in English to reflect untraditional geometry of vertical SCs and because such design involves many p-n junctions to form monolithic solar cell.

Some variations of vertical multijunction SC are shown at Fig. 2. One should remark that term multijunction is also used for tandem SC. So it is better to use adjective vertical to differentiate the dissimilar approaches.

Many of the design parameters of conventional SC are the result of a series of compromises between competitive phenomena. Many concentrator SC designs have been proposed to avoid disadvantages of conventional SC for high concentrated light and to decrease ohmic losses for concentration light. The practical Russian realization of SC with cross section (simple classical version), which is represented at Fig. 3, has also a name high-voltage SC or “Photovolt”.

They have a double-sided sensitive area and are transparent for the infrared non-active spectral band. The generator featured a high sensitivity to radiation with a wavelength of 1 pm. The maximum EMF density of generator is higher than 50 V / cm2, maximum current density — 10 A/ cm2. Ordinary silicon solar modules cannot achieve such ratings. More complicated design was realized and received name matrix SC (Fig. 4 and Fig. 5) Examples of realization of small high voltage solar modules 500 V and 1000 V are shown at Fig. 6.

There were made several investigations by Chadda T., Wolf M., Sater B. et al, and some patents were published in the USA in the middle of 1970th [7-10]. Some investigations have proceeded later [11-13].

In the early of 1990s the small industrial series of SCVJ were produced in All-Russian Electrical Engineering Institute (VEI) using technological processes developed to manufacture high voltage semiconductor devices.

a

In spite of the interesting properties of vertical design of SC not many books give information on SCVJ. So authors believe that detailed (but unfortunately not full) list of references will be useful to readers. Now photovoltaic systems with concentrator are becoming commercial and one of the future practical options for concentrator systems is SCVJ.

It is possible to match the area of the photoactive face with the power distribution in the incident radiation flux, to reduce power losses in case of non-uniform incident radiation

fluxes and to increase the efficiency of the generator in case it receives highly concentrated radiation. A method of fabricating such solar cell generator is also described in this patent [33]. A cross-section and photograph of a sample of stair-like SC are shown at Fig. 7, 8.

Main characteristics

After the first stages of development SC technology when planar SC showed efficiency more than 6-8%, the SCVJ have not been considered as a real competitor of planar SC. It partly reflects the fact that main advantages of SCVJ: low series resistance and increased tolerance to the damaging radiation were not very important for usual mass terrestrial applications. But SCVJ having interesting characteristics and features can find definite niches.

The SCVJ developed in Russia showed output electric power about 3.6 kW/cm2 under the illumination of 10 kW/ cm2 Nd-laser beam with the wavelength 1.06 pm. It was obtained 32 kV from the SCVJ small module. There were achieved the voltage density about 106 V/cm2 and power density about 20 W/cm2 from SCVJ in concentration light. Temperature decreasing of voltage is about — 1.1 mV/K under illumination about 7500 “suns “.

Open circuit voltage was measured for photovolt under the impulse illumination by xenon lamp at the temperature of liquid nitrogen. For one p-n junction EMF was equal to 1.06 V (close to the value corresponding to energy gap). Temperature coefficient of voltage was increasing from 0.4 mV/oC to 2 mV/oC under increasing concentration ratio till 10W/cm2.

The spectral-probe method was developed to combine measuring of the spectral response with a scanning technique (for instance variable-wavelength laser beam probe used) [27].

The theoretical estimations [14] indicate the limit of efficiency of the SCVJ is similar to the limit of efficiency of traditional (planar) SC, and this limit can be achieved for concentrated light and with advanced technology.

We do not consider here (in short paper) review on vertical p-n-junctions using other materials but one should said that vertical multijunction solar cell technologies using GaAlAs-GaAs [29], germanium [30], silicone carbide [31], were developed in Russia at the end of 1970th.

Cascade SCVJ were made from silicon (top) and germanium (bottom); detailed investigation were published in [30].

SCVJ silicon carbide showed ability to work at very high temperatures till 200oC.

We also have to make reference to paper of researcher who does not belong to Russian or American groups [26].

Wood energy plantations represent innovative crops destined to the production of biomass for industrial use. The plantations are characterised by high planting density: in fact it ranges from 10,000 to 18,000 plants per hectare. The species mainly employed are eucalyptus, poplar trees, willows and robinias but for the Sicilian context has been proved that eucalyptus is the one that can give better results. These plantations in Sicily could product thousand of tons with a coefficient of 7 tons for ha. The following layers of the Territorial Information System have been employed for the individuation of the areas that could be potentially destined to the cultivation of short rotation coppices:

□ Land use

□ Digital Terrain Model

□ Climate

□ Geological substratum

Concerning land use, we considered the possibility of carrying out the cultivation of short rotation coppices in the following categories of present land use:

□ Presently utilised arable lands

□ Arable lands in fallow (set-aside)

□ Bare, shrubby and herbaceous grazing lands and grasslands periodically used as pastures

□ Shrubby area

The following selection has individuated areas with less than 10% slope, in order to allow the mechanisation of operations. Furthermore, since the crops are rather demanding concerning climate, we identified a limit of 500 mm of annual average rain precipitations, so that irrigation can be avoided. Such limit hasn’t involved irrigated arable lands. Making these consideration we can asses the potential areas.

Short rotation forestry could produce in Sicilian context 1.322.250,16 tons of biomass that can be transformed in wood pellets.

With the present price levels and taking into account the subsidies made available by regional regulations, such crops achieve sufficient levels of profitability. Intersecting the ecological needs of the species that could be employed in terms of climate and soil with the economic characteristics of mechanisation and competition with other crops, it was possible to estimate that in Sicily biomass-producing crops could be extended to around

350.0 ha. As mentioned above in order to develop these sector a relevant incentive from public administration is necessary for planting the crop.

The renewable energy potential within Europe’s borders would actually be almost capable of satisfying current electrical energy demand. Wind energy is already close to being economically competitive and exhibits a huge technical potential throughout the continent. Due to high population densities, however, any major expansion of wind capacities within the European Union would be confronted with far greater impediments than those encountered in deserts, steppes, tundra, and other regions largely devoid of human settlement.

For example, the available wind energy potentials on land sites in Germany are theoretically adequate for replacing 17% of existing electricity generation, yet implementation is becoming increasingly more expensive, since the most favourable sites are already being employed. The use of local photovoltaic (PV) installations appears very costly at current prices. An additional major energy source of the future will be offshore wind power, the potential of which is frequently underestimated. It would generally be advisable to exploit the wind resources of all Eu member states. Remarkably, however, areas with the greatest wind potential such as Great Britain and neighbouring Norway have achieved only modest growth in the past [IEA 03] [WpM 03]. Even if capacities were appreciably expanded, the effects of fluctuating output could be accommodated by existing power stations in those countries for many years up to relatively high proportions of the total electricity production, as is already being experienced in Denmark, Germany and Spain. As long as the total contribution from wind energy lies below 20%, no insurmountable problems may be anticipated (s. e. g. [Gie 00]). If the power industry is dominated by storage hydropower plants, such as in the case of Norway, even greater contributions of wind energy may be easily tolerated. Yet exceeding inherent system limitations would ultimately necessitate major grid reinforcement to smooth regional fluctuations, thereby combining the characteristics of production within different regions, supplanting the low capacities generally encountered in thinly populated regions, and consequently allowing a much greater contribution of renewable energies to be achieved.

Until neighbouring countries become interested in exchanging significant amounts of wind electricity to achieve the mutual benefits of smoother temporal characteristics, and until the huge potentials in distant foreign countries are tapped, however, the contribution of wind power in countries such as Germany, which is already approaching its installation limits, cannot be expected to grow significantly.

The most interesting additional resources are therefore the huge potentials of wind and solar energy beyond the borders of the EU. Both can complement varying seasonal capacities elsewhere. In the case of wind power, for instance, the coastal regions of Morocco and Mauritania are particularly advantageous due to their summer peaks in production, which are the reverse of seasonal conditions in Europe. Solar electricity from concentrating parabolic arrays could likewise complement the output of wind farms in Germany, both inland and offshore. Since electricity demand is growing more rapidly in Morocco than in EU countries, wide-area utility services could be initiated using environmentally benign technologies for local generation [DOE 02]. The immediate EU neighbour Spain is likewise experiencing above-average growth of electricity consumption and would thus be the predestined partner for initiating transnational trade in renewable energies. Even after the costs and losses of currently available transmission equipment had been deducted, wind and solar electricity could be conveyed in a cost-effective manner over distances of more than 5000 km to central Europe. The price of wind power would be significantly lower than if produced e. g. in Germany at typical generation sites, while the price of concentrated solar electricity generation could still be competitive with domestic inland wind power if the entire range of German wind sites were being employed. In addition, a supply system extending beyond the EU would permit a full renewable energy supply to be realized for the EU and its cooperating partners. By embarking onto such a large-scale renewable energy strategy, a new form of economic cooperation with developing nations could be achieved to the advantage of all parties (s. also [Czi 99] and [BBB+ 03]).

Johann Gerdenitsch, department of environmental planning and Solar Appointee of the City of Fuerth

Introduction

The increased request for suitable PV-installations, demands that municipalities have a differentiated knowledge about usable potential. Based on concrete examples of the roofing landscape of the city of Fuerth, this lecture will present methods for recording this potential. The results give a very varied picture of the different building users (eg., residential buildings, commercial industrial buildings, agricultural and public buildings) and roofing forms that are suitable for solar energy purposes. Examples of cooperation possibilities and initiatives as to how this potential can be mobilized via different means of public relations will then be outlined.

Inventory of solar energy installations and capacities

At the end of 2003 Fuerth counted 170 solar — thermal collection installations with a total collection surface of 1482 m2. Almost all of these are single installations with an average collection surface of 9m2 on one-family houses and they mainly support the heating-sytems used for the warming of domestic water.

At the beginning of 2004 a total of 111 photovoltaic-installations had been installed on Fuerth’s roofs with a total production of 1611 KWp.

Around 84 installations with a production of approx. 182 KWp are installed on private residential buildings (predominately one-family houses.)

10 PV installations with a production of about 270 KWp are on municipal buildings, 8 thereof being on municipal schools with a share of approx. 250 KWp.

Particularly in 2003/2004, farmers installed installations on agriculturally used buildings (approx. 116 installations) with a total production of around 160 KWp.

A large PV-facility constructed on the former waste disposal site in Atzenhof started operation in Dec. 2003 with a total production of 1MWp.

The waste site has been operated as a waste management plant for almost 50 years and is a consciously planned and officially approved constructional facility of the city of Fuerth.

Thus, it cannot be compared to the open space (undeveloped area) facilities in matters concerning the Renewable Energy Law and its full scope of supply (and service) should be detailed in the appraisal by the National Solar Association.

The total municipal portion of the PV-installations in the city of Fuerth accounts for 1270 KWp (79%) which is not a negligible amount.

A 10-fold increase in the solar electricity production was able to be made from 2001 to 2004.

Fig.: Development of PV-installations in the urban area of Fuerth

The roofage potential for solar energy installations

The evaluation of an inventory that was in large, made on the basis of aerial photographs, brought the following results;

From a total of approx. 22 600 buildings in the urban area, over 5000 (22 %) are suitable for using for solar energy. [34]

picture: existing solar installations and the roofage potential in the village
structured suburb of Unterfarrnbach in the city of Fuerth

The approx. 5000 PV-suitable buildings in the urban area have a surface potential of approx. 800,000 m2 that is usable for solar energy.

On approx. 4600 buildings with slanting roofs (i. e. 92 %) there is a PV suitable surface of approx. 600 000 m2 available and 200,000 m2 on approx. 400 buildings (i. e. 8%) with flat roofs.

The flat roof potential prevails particularly in commercial / industrial areas but also partially on public buildings.

How trading works

Imagine an organization, Xco. that finds itself included under a C&T scheme. Xco. must register its operations, and then have them validated by an approved environmental auditor. It will then receive allocations of permitted emissions under the relevant process: either though an auction or by the process known as grandfathering whereby allocations are made pro rata with reference to Xco.’s previous emissions. Xco. must then assess the relative costs, in its own situation, of the following four options: to meet its allocation in full; over-emit and buy permits; under-emit and sell permits (or bank them into a future allocation perios, if permitted under the scheme); or to pay a penalty.

If required, it will arrange sale or purchase of allocations through a broker. It must report trades to the allocation registry, and then show compliance with relevant legislation. It can be appreciated that substantial transaction costs will be incurred by Xco. through this process.

Such trading systems have been applied to environmental problems since the early 1990s, principally in the US. Experience has been mixed: a successful example is the Acid Rain Program introduced by the US Environmental Protection Agency, which has been credited with halving SO, emissions from 1990-2002. The program turned out to be much cheaper than expected (possibly by half, saving up to $1.4bn): reductions were achieved by fuel substitutions rather than by the installation of scrubbing equipment.

Carbon trading

How are pollutant trading systems applied to the reduction of greenhouse gases such as carbon dioxide? There are distinct types of instrument which can be traded.

• Project-based greenhouse gas emission reduction credits, created and exchanged through a given activity: essentially a flexibility mechanism for command and control schemes [42]

US developments

There have been a number of differing proposals for carbon trading systems in the US. Discussion has been conducted at a theoretical level (see for example CBO 2001, Jacoby and Ellerman 2002) until the recent debut of the Chicago Climate Exchange. Much debate has centered around the cost effectiveness of alternative schemes: whether for example to issue allowances to “upstream” energy suppliers or “downstream” energy consumers; and how to balance the requirements of capping carbon emissions and limiting overall costs to the economy.

However slow progress on these issues may be within the Federal government, there is considerable state level activity — including the establishment of carbon registries, for example in California, which will provide the institutional framework for trading in the future. At a regional level, there are proposals for multipollutant trading that effectively extend the EPA’s Acid Rain to other pollutants: so-called 3P and 4P schemes may include S0x, N0x, Hg and C02. In further political developments, the front-running Democratic candidate for the November 2004 presidential election — John Kerry — promotes carbon trading and re-engagement with the Kyoto process. And in a bi­partisan effort, a bill to promote carbon trading was introduced by Senators McCain and Liebermann and just narrowly defeated in the US Senate in early November 2003.