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23-Chem-A5 Chemical Plant Design and Economics · May 2013

Question 2 of 7: Depreciation

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

Notes on this paper

National Exams — May 2013 — 04-Chem-A5 Chemical Plant Design and Economics. Three-hour, open-book exam; any non-communicating calculator permitted. The paper poses seven equally weighted essay questions and the candidate answers any five; only five are marked. All seven are answered below for completeness. These are conceptual design-and-economics questions — the solutions are written as organised prose (clarity and organisation are explicitly marked). The one numerical illustration (a Canadian Capital Cost Allowance schedule in Q2) is worked from stated assumptions.

Reference texts: M.S. Peters, K.D. Timmerhaus & R.E. West, Plant Design and Economics for Chemical Engineers (5th ed., McGraw-Hill) — the exam's named primary text (cost estimation, profitability, depreciation, optimisation); R. Turton et al., Analysis, Synthesis, and Design of Chemical Processes (4th ed., Prentice Hall) — process synthesis, safety, and economics; W.D. Seider et al., Product and Process Design Principles (3rd ed., Wiley) — separation-train synthesis and heuristics; supporting Canadian tax practice from the Canada Revenue Agency Capital Cost Allowance classes and the half-year rule.

Question 2: Depreciation (20 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

What depreciation is, in a tax sense. A capital asset — reactors, columns, buildings — is bought once but delivers service over many years, so its cost cannot be expensed in the year of purchase. Depreciation is the systematic, book-keeping allocation of that capital cost over the asset's useful life. Crucially for the corporation, depreciation is a non-cash, tax-deductible expense: it is subtracted from revenue when computing taxable income, so it lowers the income-tax liability without any cash actually leaving the company that year. The cash saved equals the depreciation amount multiplied by the corporate tax rate, and this "depreciation tax shield" is why depreciation matters so directly to on-going finances. In Canada, tax depreciation is not the straight-line figure carried on the financial statements but the Capital Cost Allowance (CCA) prescribed by the Canada Revenue Agency: assets are grouped into classes, each with a declining-balance rate, and only the class rate may be claimed for tax.

Current value versus salvage value. The current value (book value; in the CCA system the undepreciated capital cost, UCC) is the original installed cost minus the depreciation accumulated to date — what the asset is "worth" on the books at a given moment. The salvage value is the estimated proceeds recoverable when the asset is finally retired and disposed of at the end of its service — its market or scrap value at disposal, independent of the book calculation. The two need not agree: an asset can be fully written down (low book value) yet still fetch a meaningful salvage price, or vice-versa; any gain or loss on disposal relative to book value has its own tax treatment.

Recovery period. The recovery period is the length of time (number of years) over which the capital cost is written off for tax — the depreciable service life assigned to the asset's class. Under a declining-balance system such as CCA, the recovery period is expressed through the class rate rather than a fixed number of years, but it plays the same role: it sets how quickly the capital cost, and therefore the tax shield, is recovered.

Illustration — a Canadian CCA schedule (Check assumptions below). Consider installed process equipment of capital cost $C=\$500{,}000$ in a class with a declining-balance CCA rate of $30\%$, subject to the half-year rule in the year of acquisition, at a corporate tax rate $t=25\%$.

  1. Year 1 — half-year rule. Only half the normal allowance may be claimed in the acquisition year: $$CCA_1 = C\,r\,(0.5) = (\$500{,}000)(0.30)(0.5) = \boxed{\$75{,}000}$$ leaving an undepreciated capital cost $UCC_1 = \$500{,}000-\$75{,}000 = \$425{,}000$.
  2. Year 2 — full declining balance. The full rate now applies to the remaining UCC: $$CCA_2 = UCC_1\,r = (\$425{,}000)(0.30) = \$127{,}500,\qquad UCC_2 = \$297{,}500.$$
  3. Year 3. Continuing the declining balance, $$CCA_3 = UCC_2\,r = (\$297{,}500)(0.30) = \$89{,}250,\qquad UCC_3 = \$208{,}250.$$
  4. Tax shield. The cash saved by the Year-2 allowance is $CCA_2\,t = (\$127{,}500)(0.25) = \$31{,}875$ — real money kept in the business purely because depreciation reduced taxable income.
QuantityValue
Year 1 CCA (half-year rule)$\$75{,}000$
UCC after Year 1 (current/book value)$\$425{,}000$
Year 2 CCA$\$127{,}500$
UCC after Year 2$\$297{,}500$
Year 3 CCA$\$89{,}250$
Year-2 depreciation tax shield (at $25\%$)$\$31{,}875$

Check: the schedule assumes a single Class with a 30% declining-balance CCA rate, application of the half-year (50%) rule in the acquisition year, no additions/dispositions in the class, and a flat 25% combined corporate tax rate. Actual rates depend on the CRA class and the federal/provincial combined rate in force.