Figure 3: Screenshot of the PVGIS WebGIS

From the WebGIS it is possible to calculate values referring to potential PV energy generation after selecting the main characteristics of the desired PV installation. Similarly computations can be made for monthly radiation and daily radiation entering the aspect to take into account in the calculation. Concerning PV potential energy, the method can be applied only on PV technologies that do not depend strongly on the solar spectrum, and do not show effects of long term exposure to irradiation or high temperatures. Therefore, at the moment PVGIS does not try to calculate the output of amorphous silicon modules which are more dependent on these two effects.

4. Critical review

During the latest years attention towards RESs has led to the construction of many GIS applications aiming at informing on different aspects of RESs availability, its potential, applications and related technologies. However, it must be highlighted that even by taking into consideration the entire national territory some states are lacking available geographic models for one or more RESs

1. Methodology

The system architecture environment more commonly adopted are ArcGIS and Google Maps. Usually the former is used when more complex datasets are entered in the WebGIS. Commonly OGC interrogation protocols and specifically Web Map Service (WMS) standard are adopted and used to share data (e.g., Transenergy, Atlante Nazionale Biomasse ENEA, Geothermic Low Enthalpy Viewer, PVGIS). However, also other standards are used (e.g., WFS in transenergy).

Furthermore, the information more commonly found on the applied methods is that which is considered at the basis of the development of databases and the practical application; hence, an overview analysis of the state of art. These are generally reviews of the literature and of completed or on-going projects, carried out previously or simultaneously to the collection of data and maps from other databases and sources (for instance the Romanian Geoportal Geofizica contains information from the geological atlases and maps together with data form geological reports). The collected information is then normally directly inserted without any further analysis or after simple elaborations (calculation of more specific parameters) in a geographical environment through georeferentiation. Transenergy, PVGIS, T-JAM and BioEnerGIS are knowledgeable for their in-depth explanations reporting information on interpolation methods, applied models and harmonization of datasets that can be found in several specific guides and manuals.

2. Graphic Display

The latest group usually presents only the location of the plant/installation and the related characteristics. For example by clicking on top of the plant icon, which is displayed differently according to the type of resource used, other information is viewed (e.g., commonly the installed capacity is divided between thermal and electrical). Furthermore, the background map usually gives information on administrative boundaries (e.g., province/county).

Instead the former group is more heterogeneous due to the type of data. Data on geothermal resources usually represent the presence of wells and springs together (spatially punctual data) with temperatures at different depths (spatially continuous data). Similarly, solar source is represented by spatially continuous data (e.g., irradiation). On the contrary, available biomass considering also that for biogas production, is usually represented with total values for a given area (e.g., regions) and in some cases divided in quantitative classes (however see BIOPOLE where pixel resolution is 500X500 m).

3. Geographical extension and scale of information

To a certain degree, a related issue highlighted by some projects is the need of combining datasets and maps with different scales of precision (e.g., the Romanian Geoportal Geofizica uses maps with scales from 1:200,000 to 1:50,000).

4. General considerations

The process of creating such a tool (WebGIS) should be extensively explained in order to inform the users on the strengths and weaknesses of the applied methodology and to enable its replication. However, a schematic summary will be important to enable a quick identification of the methodology applied and of the protocols and standards adopted. Furthermore, attention shall also focus on the basic assumptions and methods of data harmonization and joining datasets. This largely depends on the type of data available and the specific aims. Finally, this type of transparency will decrease the risk of confusion as different information will be available for several RESs.