I've got a question regarding the Form 860 data about US power plants.

It is organized block-wise and not plant-wise. To become useful, the capacity numbers must be summed up.

How may I get the total capacity for each technology for each plant (by name or id)?

Plant ID,Plant Name,Nameplate Capacity (MW),Technology,...
3,Barry,153.1,Natural Gas Steam Turbine,..
3,Barry,153.1,Natural Gas Steam Turbine,..
3,Barry,403.7,Conventional Steam Coal,..
3,Barry,788.8,Conventional Steam Coal,..
3,Barry,195.2,Natural Gas Fired Combined Cycle,..
3,Barry,195.2,Natural Gas Fired Combined Cycle,..
10,Greene County,299.2,Natural Gas Steam Turbine,..
10,Greene County,269.2,Natural Gas Steam Turbine,..
10,Greene County,80,Natural Gas Fired Combustion Turbine,..
10,Greene County,80,Natural Gas Fired Combustion Turbine,..
10,Greene County,80,Natural Gas Fired Combustion Turbine,..

Only summing up is easily doable with SUMIF in Calc or Excel, but how to filter by technology? So I've better wanted to do this by pure CSV processing.

Is this possible with e.g. Python? Thanks for any good answer!

With Python, you can use the 3rd party Pandas library:

Read your Excel file into a dataframe

import pandas as pddf = pd.read_excel('file_in.xlsx')

Calculate GroupBy with sum

Grouper key(s) may either be a scalar or a list. For example, these are both valid:

res = df.groupby('Technology')['Capacity'].sum().reset_index()
res = df.groupby(['ID', 'Name'])['Capacity'].sum().reset_index()

We use reset_index to return a dataframe.

Export back to Excel

res.to_excel('file_out.xlsx')