That’s what I was going to suggest. Not a real “Excel solution” but it should work fine. I’m not sure if Excel actually has a replace function. If not, copy and paste into Word and do it there.
@AlsoNamedBort’s second method (to convert “Text to Columns” under the Data tab and select spaces as the delimiter with “Treat consecutive delimiters as one” checked) is the correct and robust way to do this operation. The “find and replace” method will work provided that the formatting is completely consistent for each cell but it is fragile because if you are using cut & paste from a webpage or a PDF that consistency is not guaranteed. It is better to learn the correct (i.e more robust) way of doing things rather than the expedient rote method that fails on you when everything is not just so. This method will also work for longer lines of data or ones where the units may differ.
All the find and replace and MID or LEFT options above are fine … with one issue.
The formula result is text, not a number so you can’t (readily) total them or run numeric formulas e.g. multiply by the billing rate to show the daily cost.
On the assumption that all the cell entries are in the generic format: 999.99 kWh
a formula to do what you are looking for is: =VALUE(LEFT(A1,FIND(“k”,A1)-1))