I’ve been thinking about the cost comparisons for different electricity sources, and the way in which they often use LCOE as the measure when comparing the different technologies. LCOE is the energy price required for the project to have an NPV (or profit) of 0. Its calculation is complicated and difficult to do by hand, so I tried inventing a far simpler method I call Endowment Pricing, seeing whether it achieved results similar to the technically correct LCOE while being simpler.

The Simplicity of Endowment Pricing

A particular amount of assets earns a certain cashflow in each year. A particular cashflow is equivalent in value to a certain sum of assets. If 100$ in a bank account earns 5$ forever, then a bond earning 5$ forever is equal in value to 100$ in a bank account. In this way, all recurring incomes and expenses can be made commensurate with one-time investments, while being consistent with the more "correct" yet complex LCOE calculations. This principle lets us make a simple system for calculating the costs, both upfront and long-term, of some investment or project.

The cost of an upfront investment, is simply what you pay for it. The formula for handling recurring costs is slightly more subtle. What we need is a start amount that we set aside, \$s\$, a multiple of how much that money grows while we wait, \$m\$, and the cost we’re ultimately having to pay, \$c\$. We have to know how much money we have to put in start with, and set aside that much money to pay the recurring cost.

\$sm = c\$

However, this is still not enough. If we start with s = 500, m = 2 and c = 1000, then we end up starting with $500, waiting for it to double in value, paying the cost, and ending up with 0$ at the end of it. We need to end up with s, so that we’ll have s after paying the cost, which is enough money to replace it again and still have s left over next time, as well.

\$sm = c + s\$

We want to have s as a fraction of c. To do this, we have to solve this equation:

\$c/{(m-1)} = s\$

m is simply your total return while waiting, when you earn a return of \$r\$ over the lifespan of your investment, \$l\$. The formula thus becomes:

\$c/{(1+r)^l-1} = s\$

The end result is a simple process for calculating how big an endowment you’d need, such that you’d be able to enjoy a particular asset perpetually into the future. You’d need to pay the cost to buy it to begin with (\$c\$), replace the original investment at the end of its lifespan (\$l\$), discounting your original investment its discount rate (\$r\$), and repeating this process with every cost that you’re paying. We can put all this into a single, simple equation:

\$Endowment C\ost = c + c_r/{(1+r)^{l_r}-1} + c_1/{(1+r)^{l_1}-1} + ... c_n/{(1+r)^{l_n}-1}\$

Let’s try this with a few actual numbers, from Lazard’s most recent round of LCOE calculations. I took the most optimistic estimate in each of the categories from their site.

Cost Nuclear Solar Wind

Upfront Cost

8475

700

1025

Capacity Factor

90%

30%

55%

Capacity Cost

9415

2335

1865

Discount Rate

7%

7%

7%

Lifespan

40

30

20

Replacement Cost

1235

305

480

Fixed O&M

135

7

20

Variable O&M

35

0

0

O&M Reserve

2430

100

285

Heat Rate

10450

-

-

Fuel Price per MMBTU

0.85

-

-

Fuel Price per kWy

75

-

-

Fuel Reserve

1070

-

-

Endowment Cost

14150

2740

2630

Relative Cost

5.380

1.041

1.0

My findings are that endowment pricing achieves results quite similar to that of the LCOE calculations. Solar and wind are near-identically priced, with nuclear being 5.4 times more expensive. The Lazard study found that nuclear energy, at an LCOE of 141$ in their optimistic case, was 5.875 times more expensive.

I suspect that the difference comes down to differences in rounding on both ends. When comparing my endowment costs to their LCOE estimates per MWh, I found that the ratio was quite consistent:

  • The solar endowment cost was 2630$, ~110 times the LCOE

  • The wind endowment cost was 2740$, ~115 times the LCOE

  • The nuclear endowment cost was 14150$, ~100 times the LCOE

My conclusion is that endowment pricing is a simple tool for comparing the costs of different potential investments. It uses a very simple and direct method of making upfront and recurring costs commensurable: it calculates how much money you need to invest as an extra upfront cost, such that all recurring costs are paid in advance. It makes estimating the potential value of savings due to new technology, and the appropriate level of spending on R&D, as simple as comparing it to the endowment cost already invested.

Given its simplicity of calculation, its ease of interpretation, and how it inherently treats long-term and short-term expenses equally, endowment pricing is an accounting technique that’s uniquely useful for public accounting. Putting all the expenses for any project or investment upfront, leaves no room for dishonest politicians or deceptive accounting to underestimate the cost of their new policies. Switching from a system of invisible liabilities slowly building up, to one where costs must be written down and paid for on day one, is both more honest and more understandable. That’s why I think it’s ultimately a superior accounting method that should be used by anyone wanting to compare the costs of different technologies, or wanting to find an honest estimate of the cost of a given government program.