7. Calculated fields

How does plant efficiency affect emissions intensity?

Presumably, more efficient plants will have a lower emissions intensity. Can we prove this?

Unfortunately, we don’t have an emissions intensity or efficiency Measure. We need to create these.

Let’s start a new worksheet and go to Analysis -> create calculated field:

7.1. Create emissions intensity field (CO2 per MWH)

We can create an emissions intensity by dividing the “Reported CO2e emissions” Measure by the “Net Generation” Measure. The syntax requires measure names (or dimensions) to be in Bracketts:

Calculated fields work very similarly to Excel equations, except they often do column by column calculations rather than cell by cell (e.g. A * B rather than A1*B1, A2*B2, etc).

7.2. Create efficiency field (energy output / energy of fuel input)

Let’s also create an efficiency measure, defined as the energy produced divided by energy within the burned fuel. That is, ([Net Generation (Megawatthours)]*3.412)/[Elec Fuel Consumption MMBtu]. Note the unit conversion, from Megawatthours to MMBTU.

Let’s put the efficiency measure on the Columns, and emissions intensity on the Rows (and color / filter on fuel type, as before):

At first, things look very wrong. But, this is likely due to an issue with some data-points rather than an issue inherent in our calculations. Maybe some of the data is just bad. Let’s exclude some of the bad data-points and see if there’s any picture for at least most of the data.

We know efficiency cannot be negative, and cannot be more than one. So, we can Filter the data based on efficiency. Drag the efficiency measure onto Filters, and filter on all values:

Still not a great picture. Let’s exclude some of the extreme values on the emissions intensity. Assume any emissions intensity above 3.0 is bad data.

Finally, an interesting picture! It’s noisy data, but the general trend indicates that more efficient generators have a lower emission intensity. Furthermore, natural gas plants have a larger efficiency range, whereas coal is fairly clustered. (what other factors could affect this stuff?)

So we’ve really dug into greenhouse gas data and done some cool analysis. But, what about other environmental releases? We can link in the EPA Toxic Release Inventory.

SUBPAGES (10): 1. INTRODUCTION 2. CREATING 2-D GRAPHS 3. 3-D GRAPHS AND MORE! 4. MAPS 5. MERGE IN EIA POWER PLANT DATA 6. DOES THE AMOUNT OF ELECTRICITY GENERATED INFLUENCE GHG EMISSIONS? 7. CALCULATED FIELDS 7. CALCULATED FIELDS 8. TRI DATASET & TABLE CALCULATIONS 9. DASHBOARDS