cnx_vinyl/docs/sustainability.md

# Sustainability

Two commitments are fixed design requirements for this plant, not aspirations
to be traded away during engineering: run on as much renewable energy as
possible, and discharge no contaminated water. Both are decisions we can
actually make, because the two biggest utility systems (steam and cooling)
are explicitly excluded from the Newbilt scope and will be sourced and
installed locally in Thailand. That gives us a free hand to spec them green
from day one.

## Renewable energy: large solar installation

The pressing machinery itself is a modest electrical load: 32 kVA connected,
~21 kW average for a full Duplex line. The real energy demand sits in the
utilities around it, above all the steam generator (400 kg/h saturated steam
at 10 bar / 180 °C) and the 250 kW cooling system.

- A large rooftop/ground PV installation is planned. Northern Thailand's solar
  irradiance is favorable, and daytime-heavy production shifts align well with
  PV output.
- The chosen hardware direction: multiple large **Deye** three-phase hybrid
  inverters (30 to 80 kW class, parallelable up to 10 units) paired with a
  **Gobel Power** high-voltage LiFePO4 battery stack at **271 kWh** (15
  stacked 18 kWh packs, LFP 314 Ah cells, rated 8000+ cycles). Deye is an
  officially supported protocol on the Gobel BMS, and Deye has established
  Thai distribution. Two engineering checks are open: matching the battery
  rack's DC voltage window to the specific Deye model (a full 15-pack rack
  can exceed the 800 V window of the smaller Deye series), and obtaining
  Gobel's safety certifications (not published) for a Thai commercial
  install. At 271 kWh the stack is a peak-shaving and ride-through buffer,
  not full off-grid autonomy, against loads like the 250 kW cooling system.
- The machine load and cooling system are straightforward PV targets.
- Steam is the open engineering question. Options under evaluation include an
  electric boiler (maximizes the solar share), a biomass boiler (locally
  abundant fuel), and solar-thermal pre-heating of boiler feedwater. No
  technology choice has been made yet; it will be driven by honest numbers on
  load profiles, storage, and grid backup, not by what sounds greenest.
- Whole-factory HVAC (continuous temperature, humidity, and PM control, see
  [facility systems](facility-security.md)) adds a major tropical-climate
  load on top of process cooling and must be part of the PV and battery
  sizing.
- System sizing (kWp, storage, grid-connection model) is open until the site
  is chosen.

### Roof design for PV (candidate Mueang Chi site)

Sized against the candidate 5-0-66.5 rai parcel in Mueang Chi (18.4708 N,
98.9642 E), whose narrow skewed shape fixes how the building can sit. Two
findings drove the roof form:

- **Orientation barely matters at this latitude.** An annual geometric
  clear-sky model puts the optimum fixed tilt near 18° facing due south, but
  the response is very flat — at 10° tilt, swinging the azimuth from due
  south to ESE costs under 2%. Rotating the building toward due south would
  gain **under one percentage point** of yield while cutting boundary
  clearance from 16 m to 12 m. The building therefore stays aligned with the
  plot, which also keeps truck circulation on the site's long axis.
- **Roof form matters more than orientation.** The plot puts the long axis on
  a 212° bearing, so a symmetric gable would strand half the array on a
  WNW-facing slope worth only ~94% of ideal. A **monopitch roof at 10°,
  falling toward ESE**, puts the entire roof on one plane at ~98% of ideal
  and yields a single uninterrupted rectangular array field — simpler
  racking, stringing, and roof penetrations.

10° was chosen over a shallower pitch deliberately: the yield difference
between 6° and 10° is under 0.2%, but northern Thailand's dry-season dust and
burning haze make self-cleaning in the rains worth more than the ~1.8 m of
extra building height the steeper pitch costs.

| Item | Figure |
|---|---|
| Sloped roof plane | ~1,520 m² |
| Module assumed | generic 580 W, 2,278 × 1,134 mm (~225 W/m²) |
| Modules (1 m perimeter strip, walkway every 4 rows) | 425 |
| Installed capacity | **~247 kWp** |
| Array coverage of the roof plane | 72% |
| Expected yield | **~335 to 360 MWh/yr** |
| Share of mature two-shift use (1,000 to 1,500 MWh/yr) | ~25 to 35% |

**No module has been selected.** The 580 W / 2,278 × 1,134 mm figure is a
generic placeholder for the current large-format n-type TOPCon class (the
size and power band shared by Trina Vertex, JA Solar DeepBlue, Longi Hi-MO
and Jinko Tiger Neo in their 570 to 600 W ratings), chosen so the layout
count is realistic. Capacity scales almost linearly with whatever module is
actually procured: the roof fits ~425 modules of that footprint, so a 550 W
module gives ~234 kWp and a 620 W module ~264 kWp. String sizing must then be
matched to the Deye inverters' MPPT voltage window before anything is fixed.

Caveat on method: the tilt/azimuth comparison is a geometric clear-sky model,
so it is reliable for **ranking** orientations but not for absolute energy.
The kWh/kWp figure behind the yield column is the regional 1,400 to 1,500
kWh/kWp/yr assumption, derated to ~98% for the ESE azimuth. Confirm against
PVGIS or a TMY dataset before committing capital.

This supersedes the older "150 to 200 kWp on a ~1,500 m² roof" figure in
[scale](scale.md), which assumed lower module power density; current
large-format modules reach roughly 225 W/m². Roughly 70 m of plot depth
remains undeveloped behind the building for ground-mount, which matters if
the electric-boiler route is chosen.

### Energy efficiency architecture: recover before generating

The deepest efficiency in this plant comes from its own thermodynamics: the
steam's job is to heat the molds, and the cooling water's job is to remove
that same heat again, so roughly 98% of the 250 kW cooling load is heat
leaving the press molds, put there almost entirely by the steam, and the
press cooling return exits at ~60 °C. That
warm return is a premium heat source, and the architecture is built around
reusing it before generating anything new:

- **Feedwater heat recovery**: a water-to-water heat pump lifts the 60 °C
  press cooling return into boiler feedwater at 90 to 95 °C. Each kWh it
  consumes does double duty: it cuts the boiler's work and removes load from
  the chiller at the same time. Together with condensate return, this saves
  roughly 10 to 15% of steam energy while shrinking the cooling system.
- **Waste heat for low-grade consumers**: the label dry oven and HVAC
  dehumidification reheat (the 35 to 60% RH spec means air is cooled below
  dew point and reheated continuously) run on recovered press heat instead
  of fresh electricity.
- **Solar thermal feedwater preheat**: flat-plate or evacuated-tube
  collectors reach 60 to 90 °C trivially in the Thai sun; cheap, proven, and
  stackable with the heat pump recovery.
- **Steam accumulator**: the presses draw steam in bursts, so an accumulator
  (already a Newbilt option) lets a smaller boiler ride the peaks.
- **The boiler only does the final lift**: whichever technology is chosen
  (electric, LPG, or biomass), it supplies just the last step to 180 °C /
  10 bar from already-hot feedwater.

Two honest exclusions, checked and ruled out:

- **Heat pumps cannot make the final steam**: commercial steam-generating
  heat pumps top out around 120 to 165 °C at lower pressures than the fixed
  Newbilt spec of 10 bar / 180 °C; hybrid heat-pump-plus-compression systems
  exist as industrial pilots, but core utility reliability is the wrong
  place to pioneer.
- **Ground-source (earth temperature) does not work in tropical Thailand**:
  the ground sits at 28 to 30 °C year-round, far too cold to be process heat
  and warmer than the 20 to 25 °C cooling loop wants, so boreholes help
  neither side. That budget is better spent on PV panels.

Fuel-side context for the boiler choice: there is no natural gas pipeline in
northern Thailand, so gas firing means an on-site bulk LPG tank (roughly 2.5
to 5 tonnes, with hazardous-storage separation distances and licensing), and
diesel means a fuel tank with price exposure. The electric and biomass paths
avoid a fossil tank on the property entirely, which matters for both the
sustainability commitments and the BOI story.

## Water supply

The zero-discharge commitment below governs water *leaving* the plant. It
says nothing about water arriving, and that side is still open: **no source
has been confirmed for the candidate site** — PWA mains, a licensed deep
well, or both. That choice drives storage, treatment, and part of the
utilities budget.

Estimated demand at mature two-shift operation (16 h/day):

| Draw | m³/day |
|---|---|
| Cooling tower evaporation | 6.0 |
| Cooling tower blowdown (4 cycles of concentration) | 2.0 |
| Boiler makeup + blowdown (80% condensate return) | 1.6 |
| Galvanics rinse, after the recycling below | 3.0 |
| Domestic, canteen, showers (25 staff) | 2.0 |
| **Total** | **~15, call it ~20 with margin** |

The cooling tower is over half of it — worth remembering when the heat
recovery above is sized, because every kW the feedwater heat pump lifts off
the chiller is also water the tower does not evaporate.

Storage is **two tanks, not one**:

- **Fire reserve ~200 m³** — dedicated, never drawn on by process or
  domestic, per [facility security](facility-security.md).
- **Raw/process ~50 m³ usable** (5 m dia × 3 m) — roughly 2.5 days at peak,
  feeding a softening/RO skid for boiler feedwater and dosing for the tower.

A **combined ~250 m³ tank**, with the fire volume protected by taking the
process suction from a higher level, is cheaper and has a real side benefit:
process turnover stops the fire reserve going stagnant. Worth pricing — but
only the fire design and the insurer can approve it, so the split above
stands as the safe default until they do.

Open items: confirm the source, its yield and its quality (a well needs a
licence and a pump test; hardness and iron set the treatment spec), and
settle whether racking height pushes the fire reserve past 200 m³ before
either tank is ordered.

## Zero contaminated water

The reference process schematic shows a conventional open "dirty water"
cooling loop. We will not build it that way.

- Cooling (up to 250 kW, 220 l/min peak, roughly 98% of it mold cooling) will
  run as a closed loop with a cooling tower/chiller, so process water is
  recirculated rather than discharged.
- Steam condensate will be recovered and returned to the treated feedwater
  cycle instead of being dumped.
- The planned in-house galvanics line (silvering and stamper electroforming)
  involves plating chemistry: silver solutions and nickel baths. This is the
  hardest part of the zero-discharge commitment. Rinse water will need
  closed-loop treatment and metal recovery, designed in from the start rather
  than retrofitted.
- Solvent handling (flagged in the site requirements) will be contained and
  disposed of as controlled waste, never via wastewater.
- Target: no process-water discharge to the local environment. Detailed water
  balance and treatment design are pending site selection.

## Materials

The plant design already includes a PVC recycling loop: an in-house grinder
returns trimmings and rejects to the extruder, with the standard feed mix at
80% virgin / 20% recycled compound. Record scrap becomes feedstock, not
landfill.

For the virgin compound itself, the preference is **local (Thai/regional)
PVC sourcing if the quality meets vinyl-record specifications**. The current
supplier list (2021) is almost entirely European, with one US option;
qualifying a local compound would cut shipping distance, cost, and the
carbon footprint of the feedstock. European suppliers remain the fallback
where quality demands it.