1. The Debate
The single-use vs. stainless steel decision is arguably the most consequential choice in biopharmaceutical facility design. It affects capital investment, operating cost, turnaround time, contamination risk, product flexibility, and environmental footprint—and the right answer depends entirely on your specific situation.
The single-use bioreactor (SUB) market has grown at approximately 25% CAGR over the past decade, driven by clinical-stage companies that need flexibility and speed-to-clinic without massive capital outlays. But stainless steel still dominates at large commercial scale, where high batch volumes and decades-long product lifecycles make the upfront investment worthwhile.
Neither technology is universally superior. The question is: at what scale, batch frequency, and product type does the economics tip from one to the other? This article provides the data and framework to answer that question for your specific situation.
Single-use (SU): Bioreactor with a pre-sterilized, gamma-irradiated polymer bag as the product-contact vessel. Disposed after each batch. Also called "disposable." Major suppliers: Cytiva (Xcellerex), Sartorius (BIOSTAT STR), Thermo Fisher (HyPerforma), Merck (Mobius).
Stainless steel (SS): Traditional fixed vessels constructed from 316L stainless steel, cleaned in place (CIP) and sterilized in place (SIP) between batches. Reused for thousands of cycles.
2. Capital Cost Comparison
The capital cost advantage of single-use is dramatic. A single-use facility requires no CIP/SIP systems, minimal piping, simplified HVAC (no steam generation), and reduced cleanroom classification in many areas. The savings compound throughout the facility:
The facility timeline is equally different. A single-use facility can be designed, built, and validated in 18–24 months. A stainless steel facility typically requires 36–60 months. For a company racing to supply a newly approved product, this time difference can be worth more than the capital savings.
These are facility-level costs, not bioreactor-level costs. A single 2,000 L SUB vessel costs $200–400K, while a 10,000 L SS vessel costs $500K–$1.5M. The real cost difference is in the infrastructure required to support the vessels. Single-use dramatically simplifies the facility.
3. Operating Cost Comparison
While single-use wins on capital, stainless steel often wins on operating cost per batch—especially at high batch frequencies. The key tradeoff is consumables vs. utilities.
Single-Use Operating Costs
- Biocontainer (bag): $2,000–5,000 per 2,000 L bag
- Tubing, connectors, sensors: $1,000–3,000 per batch
- Filters (0.2 μm, depth): $1,500–4,000 per batch
- Sampling assemblies: $500–1,500 per batch
- Total consumables: $5,000–15,000 per batch
At 100 batches per year, consumables alone cost $500K–$1.5M annually. This cost scales linearly with batch number—no economies of scale.
Stainless Steel Operating Costs
- CIP chemicals (NaOH, acid, sanitizer): $200–500 per cycle
- Water for Injection (WFI): 5,000–10,000 L per CIP cycle at $0.50–$2.00/L
- Steam for SIP: $100–300 per cycle
- Labor (CIP/SIP validation, monitoring): $500–1,500 per cycle
- Total per CIP/SIP cycle: $3,000–8,000
But stainless steel also requires ongoing maintenance: gasket replacement, valve servicing, re-passivation, and periodic requalification. These add $50K–200K per vessel per year in fixed costs regardless of batch frequency.
Labor Comparison
Single-use requires fewer operators because there is no CIP/SIP to run, monitor, and validate. A typical CIP/SIP cycle takes 8–24 hours of vessel time and 2–4 hours of operator attention. With single-use, turnaround between batches can be as short as 4–8 hours (bag change, line setup, leak test). This translates to higher facility utilization and fewer FTEs.
4. The Crossover Point
The crossover point—where the total cost of ownership (capital + operating) is equal for single-use and stainless steel—depends on two primary variables: scale and batch frequency.
Scale crossover: ~2,000–5,000 L working volume
Frequency crossover: ~100–200 batches/year
Below both thresholds: single-use is cheaper
Above both thresholds: stainless steel is cheaper per batch
Mixed (small scale + high frequency, or large scale + low frequency): case-by-case
The scale crossover exists because single-use bags above 2,000 L become increasingly expensive and have engineering limitations (mixing, heat transfer, kLa). The largest commercially available SUBs are currently 4,000–6,000 L, compared to stainless steel vessels that routinely reach 25,000 L or more.
The frequency crossover exists because single-use consumables are a per-batch cost with no amortization. After enough batches, the cumulative consumables cost exceeds the capital savings. At 200+ batches per year with a 5-year facility amortization, stainless steel almost always wins on total cost.
The COVID-19 pandemic exposed a critical vulnerability of single-use: supply chain dependence. When multiple vaccine manufacturers simultaneously ramped up SU demand in 2021–2022, lead times for biocontainers extended from 4–6 weeks to 6–12 months. Stainless steel vessels, once installed, have no such supply chain risk. Factor this into your risk assessment.
5. Head-to-Head Comparison
| Factor | Single-Use | Stainless Steel |
|---|---|---|
| Capital cost | Low ($50–100M facility) | High ($200–500M facility) |
| Turnaround time | Fast (4–8h, no CIP/SIP) | Slow (8–24h CIP/SIP) |
| Contamination risk | Lower (pre-sterilized) | Higher (cleaning validation required) |
| Maximum scale | ~4,000–6,000 L | Unlimited (>25,000 L) |
| Flexibility | High (multi-product) | Low (often dedicated) |
| Environmental impact | Plastic waste (50–100 kg/batch) | Water/chemical waste (5,000–10,000 L/CIP) |
| Leachables & extractables | Concern (E&L studies required) | Not an issue |
| kLa performance | Lower (30–150 h−1) | Higher (100–400 h−1) |
| Facility build time | 18–24 months | 36–60 months |
| Supply chain risk | Higher (bag supply dependency) | Lower (once installed) |
6. Product-Specific Considerations
The optimal bioreactor technology depends heavily on what you are manufacturing. Here is guidance by product type:
Monoclonal Antibodies (High Volume)
For established commercial mAbs with annual demand >100 kg, stainless steel at >10,000 L scale is almost always the most cost-effective option. The high batch frequency and long product lifecycle (15–20 years) amortize the capital investment. However, many companies use SU for clinical supply and early commercial launch, then transition to SS as demand becomes clear.
Gene Therapy (Small Batches)
AAV and lentiviral vector manufacturing operates at small scale (200–2,000 L) with relatively few batches per year. Single-use is the dominant choice because capital efficiency matters more than consumables cost, and multi-product flexibility is essential (most gene therapy CMOs make multiple products).
Cell Therapy (Patient-Specific)
Autologous cell therapies (CAR-T) are manufactured in individual patient batches, typically in closed, single-use systems. Stainless steel is impractical for this application. Single-use is not just preferred—it is the only viable approach for patient-specific manufacturing.
Biosimilars (Cost-Driven)
Biosimilar manufacturers compete primarily on cost. For established biosimilar products with proven market demand, stainless steel at large scale provides the lowest COGS. Several large biosimilar manufacturers in Asia operate 10,000–25,000 L stainless steel facilities specifically for cost competitiveness.
Clinical Supply (Flexibility)
During clinical development, the ability to quickly switch between products in the same facility is paramount. A single-use facility can manufacture Product A on Monday and Product B on Wednesday with no cross-contamination risk. This flexibility is nearly impossible with dedicated stainless steel vessels without extensive changeover procedures.
Model Your Production Economics
Compare COGS for single-use and stainless steel scenarios with our Fermentation Economics tool.
Fermentation Economics →7. The Hybrid Approach
The most pragmatic solution for many manufacturers is a hybrid facility that combines single-use upstream with stainless steel downstream. This approach captures the benefits of both technologies where they are strongest.
Why Hybrid Works
- Upstream (bioreactors): SU bags are well-suited because each batch requires a fresh, sterile vessel. The contamination risk reduction alone justifies SU in many cases. Scale limits (2,000–4,000 L) are acceptable when multiple SUBs run in parallel.
- Downstream (chromatography): Chromatography columns and resins are inherently reusable—they are designed for hundreds of cycles. Single-use chromatography is expensive and generates massive waste. SS columns with CIP between cycles are far more economical.
- Filtration: TFF cassettes are typically single-use or limited-use regardless of the upstream technology. Depth filters and 0.2 μm filters are always single-use.
The hybrid model is increasingly the default for new mAb facilities built since 2020. It provides the fast turnaround and contamination safety of SU upstream with the cost efficiency and performance of SS downstream.
8. Environmental Perspective
The environmental debate between single-use and stainless steel is more nuanced than it first appears. Each technology generates a different type of waste:
Single-Use Waste
- Plastic waste: 50–100 kg per 2,000 L batch (bags, tubing, filters, connectors)
- Primarily polyethylene (PE), ethylene vinyl acetate (EVA), and polycarbonate
- Most SU waste is classified as biohazardous and must be incinerated, not recycled
- At 100 batches/year: 5–10 metric tons of plastic waste annually
Stainless Steel Waste
- Water: 5,000–10,000 L of WFI per CIP cycle, plus rinse water
- Chemicals: NaOH (0.5–1 M), phosphoric acid, peracetic acid
- Steam: Energy for SIP (saturated steam at 121°C for 30+ minutes)
- At 100 batches/year: 500,000–1,000,000 L of contaminated wastewater annually
Lifecycle Analysis
Published lifecycle assessments (LCAs) show mixed results. A widely cited 2012 GE Healthcare (now Cytiva) study found that single-use reduces carbon footprint by 33% and water use by 87% compared to stainless steel at the 2,000 L scale. However, critics note that these studies often exclude the environmental cost of plastic resin production and incineration, and that the comparison is not fair at larger scales where SS is more efficient.
The industry trend is toward recyclable single-use materials and take-back programs (Cytiva's Figurate, Sartorius sustainability initiatives), but these programs are still in early stages and cover only a fraction of SU waste.
If your primary concern is water and energy consumption, single-use is greener. If your primary concern is solid waste and plastic pollution, stainless steel is greener. A comprehensive environmental strategy considers both and selects the approach that minimizes total impact for your specific scale and location.
References
- Langer, E.S. & Rader, R.A. (2023). "Single-Use Technologies in Biopharmaceutical Manufacturing." BioPlan Associates Annual Report and Survey of Biopharmaceutical Manufacturing Capacity and Production, 20th Edition.
- Sinclair, A. & Monge, M. (2010). "Quantitative Economic Evaluation of Single Use Disposables in Bioprocessing." Pharmaceutical Engineering, 30(3), 1–8.
- Rawlings, B. & Pora, H. (2009). "Environmental impact of single-use and reusable bioprocess systems." BioProcess International, 7(2), 18–25.
- Pietrzykowski, M., Flanagan, W., Pizzi, V., et al. (2013). "An Environmental Life Cycle Assessment Comparison of Single-Use and Conventional Process Technology for the Production of Monoclonal Antibodies." Journal of Cleaner Production, 41, 150–162.