Renewable vs Non-renewable energy in the UK and Ireland (2014)

Hello, I study at Swansea University and have been tasked to create data visualizations for the global power plant database (GPPD).
I have come on here to ask how could my visual design be improved?

Image :

Visual Design Type : Digital (Symbol) Map

Name of Tool : Tableau

Country : United Kingdom, Ireland

Year : 2014

Visual Mappings :
Column: Longitude (generated)
Row: Latitude (generated)
Detail: country_long
Detail: AVG(longitude)
Detail: AVG(latitude)
Detail: wepp_id
Colour: primary_fuel_grouped [Renewable, Non-Renewable]
Shape: Sum(estimated_generation_gwh)

Unique Observation :
There is many more renewable power plants throughout the UK and Ireland but they produce a significant amount less gwh than the non-renewable sources. The spread of renewable power plants can be seen along coastlines and throughout most of scotland which can be explained due to wind and tidal energy that can be utilized with these power plants. Larger, non-renewable power plants are mostly seen in the center of the United Kingdom as this is where many populated cities are.

Data Preparation : primary_fuel was grouped into renewable and non-renewable. Null values were also removed.

This is very interesting to see the distribution of renewable and non renewable fuel sources throughout the UK and Ireland, I like that it can be seen that Scotland relies a lot less on non renewable sources in comparison to England.

Perhaps some circles are a bit small which makes it difficult to see if somebody’s eyesight is not great.

Hello Adam, thanks for the feedback! I have made the minimum size of the circles slightly larger to make reading the visualization easier, but I do not want to make the size of the circles too large as it will become hard to differentiate how many power plants there are. Here is an improved version below, please let me know if this any easier to read.