Environmental Impact Assessment

1.-INTRODUCTION.

2.-PV MODULES :

·       Introduction.

·        Manufacturing :

·        Energy analysis.

·        Emissions analysis.

·        Material flow analysis.

·        Health & Safety risks.

·        Conclusions.

·       Operation.

·        Decommissioning.

·       Conclusions.

3.-OTHER PARTS OF THE SYSTEM.

4.-CONCLUSIONS.

APPENDIX.

1.-INTRODUCTION

The concept of Environmental Impact Assessment was established under a European commission (EC) Directive that, through a series of Regulations, has legal status within the UK.  The most significant legislation regarding Environmental Assessment is as follows.

·        EC Directive (85/337): ‘The assessment of the effects of certain public and private projects on the environment.’

·        Town and Country Planning (Assessment of Environmental Effects) Regulations 1988.

·        Town and Country Planning (Assessment of Environmental Effects) (Amendment) Regulations 1994

Environmental Impact Assessment is an assessment of the impact of a renewable energy project, prior to a planning application to determine whether the project will have an adverse effect on the environment.  An environmental assessment will be  instigated for only some renewable projects, namely those that are deemed ‘likely to have significant environmental affects.’  Many renewable schemes do not require an environmental assessment as its impact is unlikely to be significant, this is determined using two categories.

Schedule 1

·        Environmental assessment is mandatory for these projects.

·        Generally large scale development with an output of 300MW.

Schedule 2

·        The project will require an environmental assessment if the Planning Authority concludes that the scheme is likely to give rise to significant environmental affects.

·         Most large-scale renewable projects fall into schedule 2 due to concerns about the proposed technology or the associated infrastructure.

An Environmental Impact Assessment involves a structured assimilation and evaluation of information regarding issues such as landscape, air quality, water quality and noise. The objective of the Environmental Assessment is to initially identify the affects and where they are deemed to be significant, establish if these can be minimised by design modifications or mitigation procedures.

The present technology of the PV – hydrogen storage – fuel cell system is unlikely to require environmental assessment under current legislation.  Although for this project we have carried out a life cycle environmental assessment for each of the major system components.

·        PV modules

·        Hydrogen storage

·        Fuel cell (similar assessment as electrolyser)

2.-PV Modules.

Introduction.

            The Environmental Assessment for the PV modules is related to the whole life of the product, i.e. manufacturing processes, operation and decommissioning.

            The most important part is manufacturing since PV modules are produced under very high energy consumption characteristics. Photovoltaic energy production is suppose to be an environmentally friendly energy system with no emissions and no waste production, clean and noiseless but it is important to ensure that manufacturing is not going to be more expensive than energy produced and manufacturing processes are not going to be more harmful for the environment than operation advantages. Then it is very important to know if the product is going to be economically and environmentally viable for the overall life cycle.

            For the manufacturing processes environmental impact, three different studies have been carried out : Energy Analysis, Energy Related Emissions Analysis and Material flow analysis.

            For the Energy Analysis the amount of energy associated to the manufacturing processes of the product are calculated to see if the production costs are comparable to the energy produced benefits.

            For the understanding of this analysis , few concepts have to be revised :

o       Gross Energy Requirement (GER) or the total amount of  primary energy incorporated in a product.

o       Process Energy Requirement (PER) or the energy required for a specific process step in the manufacturing process. This can be divided into direct PER, covering the electrical and fuel energy which is consumed during the process and indirect related to the energy used not involved in the process (i.e. lighting, heating, ventilation and others...)

The sum of PER values for all single processes involved, gives the GER value for the manufacturation of the product.

     The Energy Related Emissions Analysis is being used to calculate the quantity of CO2, NO2,NOx and particles emissions have been not released to the environment by using to this energy generation system.

            The Material Flow Analysis is an study of all the material flows during the process and its related emissions.

One of the main issues of the material flow analysis is to know if photovoltaic panels are a real possibility of electricity generation keeping in mind natural resources available for the manufacturing of the modules and taking in account that at the present there are no recycling technologies what leads to the continuos use of natural resources.

Another issue of this part of the study are the non energy related emissions to the environment, either water or air. All waste generated from PV modules production activities represent a big amount of solids that may have emissions associated to them.

            The operation study present a short review of the advantages and disadvantages of utilisation of solar photovoltaic.

            Decommissioning part encloses the key issues to keep in mind when the modules are refused.

Manufacturing.

Energy analysis.

            The energy analysis carried out is for the systems under the three different climate conditions. Table below shows the final results.

            Each area has give different number of PV panels due to the different solar irradiation conditions and energy requirements. These are:

Scotland:          210 PV panels assumed as 210 m² of cell area.

Italy:                 66 PV panels assumed as 66 m² of cell area.

Phoenix:           120 PV panels assumed as 120 m² of cell area.

For  other assumptions and detailed calculations see the Appendix.

Energy related emissions analysis.

            The energy related emissions analysis has been done to calculate the quantity of emissions not released to the atmosphere by using the system designed.

Material flow analysis.

In this part of the study we have look at two different aspects:

1.    The possibility of photovoltaic energy being a source of energy, for this, it has to be known if there are natural resources available for PV panels fabrication.

2.    Non energy related emissions either to air or water, coming from manufacturing, operation and decommissioning of PV panels.

1.    Natural resources.

            Main materials involved in PV panels manufacturing are Quartz and Silver for the contacts.

            Quartz is an abundant natural resource, so there is no point of concern about this material. But silver seems not to be very abundant. 5 g of silver are estimated to be required per m² of cell, for a supply of 5% of the world electricity requirement it would be necessary 4 kton of silver per year what is 30% of the current silver production.[Environmental aspects of solar cell modules, E.A.Aselma, Utrecht University, 1996].

            Reduction of silver is a point of concern for PV modules manufacturing, as well as cost, and research in other materials to substitute silver is necessary.

2.    Emissions to the environment.

            Other emissions than energy related emissions analysed above, released during production of monocrystalline PV modules are:

·      Fluorine.

·      Chlorine.

·      Nitrate.

·      Isopropanol.

·      SO₂.

·       CO₂.

·       Respirable silica particles.

·       Solvents.

                These emissions are mainly caused by the carbothermic silica reduction process. SO₂ emissions can be significantly reduced by using standard measures like the use of low-sulphur fuel and desulphurization of fuel gasses [Environmental aspects of solar cell modules, E.A.Aselma, Utrecht University, 1996].

            Chlorine and fluorine emissions are estimated to be around 20-25% of equivalent emissions of a coal fired electricity plant. .[Environmental aspects of solar cell modules, E.A.Aselma, Utrecht University, 1996].

            Silica particles and solvents can be minimised with a  good waste management schedule.

Operation.

Advocates of renewable solar systems argue that during operation the environmental impact of this technology is minimal in comparison with other forms of renewable energies.  This is illustrated in the following diagram.

It is during the operational phase that the module produces electrical energy, the quantity of which is dependent on the module efficiency and the location of the module.  The key benefits of PV during this phase are that it is inexhaustible and there are negligible material inputs or gaseous, liquid or radioactive pollutants discharged.  PV is also particularly safe during operation, as there are no mechanical rotating parts and  noise pollution.  If there was a fire it is anticipated there would be no significant gaseous emissions.

There are potentially similar electrical hazards associated with any PV installations as with any small-scale installation.  This includes a possible risk an electrical shock particularly when the DC voltages are higher than the standard 12-48 volts employed in most small-scale PV systems.

The visual impact of the PV installation may be one of the main issues, giving rise to local concern.  PV arrays obviously have a visual impact on the environment, as they are likely to be visible from adjacent dwellings and this may be particularly significant in conservation areas.  The visual impact will be minimised in the future as PV building integration technology is constantly improving. 

Decommissioning.

            At the end of the life time of the modules, they must be dispose in a sensitive way. At the moment there are no many options for recycling the silicon wafer. Aluminium frames can be recycled separately in the same way as this material normally is, glass could be recycle if technologies would exist to separate the glass from the adherent EVA and other module components.

            This kind of modules a formed mainly by :

·        Glass, around 78% of its weight.

·        EVA, 10% of its weight.

·        Polyester, 7%.

·        Silicon, 4%.

·        Silver, 0.4%.

·        Copper, 0.3%.

            Most of the components are environmentally harmless but special attention has to be taken when dealing with silver and copper waste, anyway quantities are relatively small and at the moment do no represent any damage.

Our recommendation for research entities is to encourage investigation to make silicon wafer recycling commercially available. Anyway, polycrystalline and amorphous silicon modules are relatively harmless compared with other types, such as Cadmium Telluride or Copper indium selenide, that may realise heavy metal emissions if incinerated.

3.- OTHER PARTS OF THE SYSTEM

Life Cycle Analysis of Fuel Cell

Manufacturing

Due to current confidentiality concerns, fuel cell manufactures were unwilling to provide us with manufacturing data.

Operation

The environmentally benign features of a fuel cell during its operational phase and its high power conversion efficiency make it an appealing source of power generation.  Fuel cell emission levels are none or minimal during operation as they do not rely on a fuel combustion process and in comparison to conventional power plants the fuel cell emissions are predicated to be reduced by 1000 to 10, 000 times.  Emissions for a fuel cell are 0.003lb/MWh of SO₂ and 0.0004lb/MWh of NOx.  Due to high conversion efficiencies of the fuel cell, between 40-60%, minimal emissions of CO₂ a during operation.  Assuming a fuel reformer efficiency of 95% and a power plant efficiency of 45% it has been calculated that emissions of CO₂ are 376.42Kg/MWh.  This is significant in comparison to battery power emissions, assuming a fuel ratio of 40% nuclear power and 60% coal, the batteries CO₂ emissions are approximately double the fuel cells at 714.3 Kg CO₂/MWh.  The low levels of pollutants emitted during the operation of a fuel cell make it suitable for use in locations where environmental constraints may be stringent such as urban centres.

Fuel cell implementation will also provide benefits in terms of minimal environmental impact on local water usage, as the fuel cell does not require any external water, instead water is actually produced as a by-product.  This is in comparison with conventional power plants that require significant quantities of local water for system cooling.  Therefore a fuel cell system will reduce ecological impact on local water systems due to a reduction in demand for water supplies.  The fuel cell does not have any mechanical rotating parts and therefore the electrochemical process eliminates any noise impact.

Decommissioning and Recycling

At the end of the fuel cells effective life it must be decommissioned and an evaluation of this stage indicates there will be no significant hazards or adverse environmental impacts.  As opposed to waste disposal the key issue is recycling of the individual components of the fuel cell system.  Component recovery is dependent on the specific fuel cell type as in a molten carbonate fuel cell (MCFC) the nickel can be recovered from the catalyst and both the electrodes.  The phosphoric acid fuel cell (PAFC) will require recovery of the elements platinum from both the anode and cathode and nickel from the catalyst.  After decommissioning the solid oxide fuel cell (SOFC) component recovery will include both the nickel and zirconium components.   

Life Cycle Analysis of Hydrogen

Manufacturing

Steel is the most common alloy, which is used to facilitate hydrogen storage in the form of both tanks and cylinders.  Modern steel making is a particularly energy intensive process and therefore has a more significant environmental impact than the operational or decommission and recycling phases.  Modern steel manufacturing employs blast furnaces to process steel from iron ore and the environmental impact, as a consequence of this production, is in the form of toxic gaseous emissions and a large expenditure of energy.  The basic materials used for the manufacture of pig iron are iron ore, coke and limestone.  The coke is burned as a fuel to heat the furnace and as it burns, releases polluting emissions of carbon monoxide, which combines with the iron oxides in the ore, reducing them to a metallic iron.  This results in the release of emissions of the greenhouse gas, carbon dioxide. 

The energy required in the furnace also has an environmental impact as the blast furnace operates continuously and the air used to supply the blast is pre – heated to temperatures between 540^o and 870^oC (1000^o and 1600^oF).  The pig iron must be transformed to steel using heat treatments, which consists of heating the metal to 760^o to 870^oC (1400 to 1600^oF) at which austenite is formed again this process is particularly energy intensive.  Other methods of heat treatments also have a negative environmental impact such as ‘carburizzing’ where the steel is heated in carbonaceous gases such as methane or carbon monoxide.

Operation

Hydrogen as a fuel has many advantageous properties, the most significant are that it is completely recyclable and is produced by an abundant completely natural means – water.  Hydrogen is initially produced by the splitting of a water molecule, in our system using energy produced by PV to power an electrolyser.  Upon the combustion of hydrogen water vapour is the principle by product which returns to the biosphere where it originated from, therefore the process is inexhaustible and environmentally benign.

The growing awareness of the role of hydrogen as a future fuel is primarily due to its limited polluting emissions during combustion.  As hydrogen obviously contains no carbon, all emissions of greenhouse gases such as CO, CO₂ and HC are essentially eliminated.  Although the combustion of hydrogen produces emissions in the form of NO and NO₂ as a result of the chemical reaction with atmospheric oxygen and nitrogen.   The nitrogen oxide emissions can be reduced and controlled, as they are dependent on the fuel - air equivalence ratio and the temperature and therefore a variable of the type of combustion.

An obvious criterion to consider during the environmental impact assessment of hydrogen is its remarkably wide combustion limits. This facilitates ease of combustion and also requires that increased precautions be taken against leaks.  The environmental damage and radiation hazards resulting from a hydrogen – air fire are minimised in comparison to a hydrocarbon fire as a consequence of the low emissivity of the hydrogen flame.  Additionally the radiation leakage from a hydrogen fire is at a wavelength, which is readily absorbed by the atmosphere.  If hydrogen does leak the risks of an explosion and thus the consequent environmental impact are minimised to the space immediately above the leak as hydrogen’s low-density means it rises very rapidly.

Decommission and Recycling

At the end of their working life period the storage tank or storage cylinders must be decommissioned and then recycled and subsequently reused as a new steel product.  This recycling process reduces the net energy required to produce a similar product from new and therefore benefits the environment.

APPENDIX.

1.-Assumptions.

            Following tables show the several assumptions made for the calculations:

2.-Energy Requirements for PV modules Manufacturing.

Energy requirements for monocrystalline and polycrystalline are assumed to be the same [2]. These are presented in table 4, table 5 shows the same values for amorphous silicon PV panels.

3.-Energy Analysis.

Energy Production.

            The energy produced by the PV modules has been calculated as follows:

·      Yearly electricity production = cell efficiency * system performance ratio * Irradiation.

·      Lifetime electricity production = years lifetime * yearly electricity production.

·      Yearly primary electricity savings = yearly electricity production divided by efficiency conversion from primary energy to electricity.

The results obtained for each type of module can be examine in following tables:

            This results are per m² of silicon cell, the system designed has different cell area for each climate studied. Next tables show energy production for each type of panel on the different climate areas studied.

Energy Pay back analysis.

Energy related emissions analysis.

There are potentially similar electrical hazards associated with any PV installations as with any small-scale installation.  This includes a possible risk an electrical shock particularly when the DC voltages are higher than the standard 12-48 volts employed in most small-scale PV systems.

The visual impact of the PV installation may be one of the main issues, giving rise to local concern.  PV arrays obviously have a visual impact on the environment, as they are likely to be visible from adjacent dwellings and this may be particularly significant in conservation areas.  The visual impact will be minimised in the future as PV building integration technology is constantly improving.