Site Engineering: What Actually Goes In the Ground

Jenja is built to be boring to install. Containerized, crane-placed, standard utilities. Here is what an engineer actually has to pour, connect, and pour concrete for.

The foundation

Nothing exotic. A reinforced concrete plinth, not a building foundation. Concrete volume runs 8 to 15 cubic meters per unit, covering both the gasifier pad and the separate engine pad, with a vibration isolation joint between them. Rebar is standard A2/A3 at a 150 to 200 mm grid. Depth is 300 to 500 mm, extending to 600 to 800 mm in frost-prone EU zones. Ground bearing pressure is 45 to 60 kN/m2 at the slab. The container ties down to four cast-in M16 to M20 anchors at the corners. A four-pier alternative cuts concrete to 4 to 6 cubic meters. One geotechnical borehole, EUR 2,000 to 5,000, is worth ten times that in avoided over-design.

The container

The unit arrives as one ventilated enclosure, roughly 6 to 8 meters by 2.5 by 2.9, about 40 cubic meters. Operating weight is 12 to 18 tonnes. Total site area including feedstock storage, ash handling, maintenance access, and setback runs 100 to 200 square meters. It needs at least 6 air changes per hour of forced ventilation, interlocked to a CO sensor, a 30 to 60 minute fire rating inside, and a roof-mounted flare stack 6 to 12 meters tall with sampling ports at two-thirds height.

The connections

Electrical is 400V three-phase, 63A, TN-S, the same service a commercial kitchen uses. Steady-state load is 2.2 to 3.7 kW. Startup heaters pull 15 to 18 kW. Gross generator output is 168 kWe, netting 100 to 130 kWe after parasitic load. Control system is a Siemens S7-1500. Water connections cover 170 to 790 liters per hour total, depending on cooling configuration, with 50 to 200 liters per hour of scrubber blowdown that needs on-site treatment. Add compressed air at 6 to 8 bar and a nitrogen bottle for startup purging, five to fifteen startups per bottle.

The timeline

The construction phase runs 8 to 16 weeks from site handover. Within that: civil works 2 to 4 weeks, equipment delivery 1 to 2 weeks, crane placement 1 to 2 weeks, utility connections 1 to 2 weeks, and commissioning 2 to 4 weeks. Cold tests to first gas to engine synchronization to a 72 hour performance run. Commercial operation lands 10 to 12 weeks after the foundation pours. One 50 tonne mobile crane covers the whole lift in a day.

The cost

Civil works and installation run EUR 50,000 to 100,000 in the EU, USD 30,000 to 70,000 in Indonesia, USD 45,000 to 110,000 in East Africa. That is 10 to 15 percent of total CAPEX. Grid connection, not the concrete, is the critical path: 3 to 12 months in every market, and it must start before permitting. The named risks are real. If the feedstock is classified as waste rather than biomass, add 2 to 6 months and EUR 10,000 to 30,000. If the site lacks a 63A supply, a transformer upgrade costs EUR 5,000 to 25,000.

One container, one crane, one concrete pour, one 63A socket. The machine is the hard part. The site around it is not.