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This page describes the purpose of our Environmental Assessment method, the assessment stages, and details of the methods used. The method has been transferred to a spreadsheet. Purpose of the assessment method Our method should apply as an assessment framework for any energy project to:
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Index of assessment methods |
Assessment stages
Identify environmental aspects and agree significance
A check list of the sustainability issues and environmental aspects is provided, together with a participative method for weighting the significance of each aspect. The significance of the aspect is that to the environment, and is considered independent of the technical solution proposed in the scheme.
Assess the environmental performance
The environmental performance of the technical solution or scheme is assessed under each aspect, using detailed assessment methods such as resource use planning and life cycle assessment, or risk assessment, depending upon the purpose of the assessment.
The most important environmental indicators for energy projects are identified, and general data provided for comparisons with alternative energy schemes.
Evaluate the environmental impact
The environmental impact is evaluated against each aspect by multiplying the environmental significance and the scheme performance.
Our method assesses the overall environmental impact by calculating a cumulative score from the specific impacts.
Details of the assessment method
Agreeing the environmental aspects and their significance
The recommended approach is to agree the aspects and their significance between the stakeholders in the project. This is achieved by involving representatives of all the stakeholders in a participative group process in the early stages of the method.
Identifying the environmental aspects
Environmental aspects are identified under the following headings:
Ranking the significance of the environmental aspects using the paired comparison method
Sheets in the spreadsheet give a paired comparison method for ranking the significance of the environmental aspects. The sheets comprise a matrix with the list of aspects along the rows and columns.
For each row, the aspect in each column is compared with the aspect in the row. When the aspect in the row is considered more important than the aspect in the column a 1 is entered. Otherwise a 0 is entered.
The spreadsheet calculates the number of 1's in each row and ranks the totals in order compared with the other rows. This provides a quantitative, if inexact method for ranking the significance of the impact as perceived by the user. This exercise is repeated by the different stakeholders using copies of the spreadsheet.
Assigning and agreeing the significance weightings
The user then assigns significance weightings to each aspect on a scale of 0 to 5 , by grouping the ranked order of aspects. The stakeholders compare the weightings they have assigned, discuss the differences, and agree as a group the weightings to be assigned for continuing the impact assessment.
The agreed weightings are entered on the master spreadsheet.
Alternative assessment criteria
The primary purpose of the method is to assess the overall environmental impact. However, the facility has been provided on the spreadsheet to assign significance weightings, assess the performance, and evaluate the impact against different criteria:
The paired comparison and weighting assignment exercise is repeated for the required assessment criteria.
Assessing performance
The proposed scheme is assessed using high level environmental assessment techniques such as resource use planning, life cycle analysis, and risk assessment. The results of this analysis are used as the basis for giving performance markings under each aspect.
Positive and negative scores
Positive scores are entered for positive impacts, and negative for adverse impacts. The total result from the assessment should therefore indicate the overall benefit of the scheme or otherwise.
Multiple performance measures
Where a number of performance measures are identified under each aspect, the applicable ones are selected by entering the significance weighting on the appropriate row.
Common performance parameters
Some quantitative performance measurements should be globally applicable, for example efficiencies and emissions to the global environment. In these cases recommended performance scores for levels of efficiencies or emissions are given in the spreadsheet. The recommended performance scores are linear with respect to the efficiencies or emissions, down to the worst case. For CO2 and SO2 emissions the worst case is based on a dirty coal fired power station. The levels of CH4 and NOx emissions have been normalised (approximately) for equivalent global warming effects to those of the CO2 levels. The data used for this is given in the reference sheets of the spreadsheet.
Substitution shifts of performance
Complicating factors are when the scheme yields a negative performance, but the net impact of the scheme is positive. An example is the use of biofuels partially substituting for fossil fuels. Since some fossil fuels will be used to make up the fuel supply inefficiency has a negative impact on the depletion of fossil fuels. However, if the scheme wasn't there, all the energy would be supplied using fossil fuels so the negative impact would be greater. Hence the performance score and net impact are shifted to a positive value. A similar case exists with methane emissions using biogas to energy, compared with situations where the waste methane would otherwise be released to atmosphere.
Evaluating the environmental impact
The spreadsheet calculates the environmental impact under each aspect, and the overall environmental impact score.
Spreadsheets
Two versions of the spreadsheet are provided. The first includes:
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Download Environmental Impact Assessment spreadsheet with significance weightings and indicative performance scores (Excel) |
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Download Environmental Impact Assessment blank spreadsheet (Excel) |
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