Mobile energy / design study 01
A compact wood-energy system for MSEC, supplied by a collection robot. Optimize the complete package, from fallen wood to usable electricity.
Analytical concept · dimensions and performance are targets
The compactness strategy Reuse MSEC’s engine where a qualified conversion permits it. Keep a dedicated all-wood option and a higher-efficiency fuel-cell study alongside it.
MSEC integration ↗Three ways to convert wood
A small reactor is only part of the system. Gas cleanup, cooling, insulation, preparation, the robot and reserve fuel all take space.
Feed cleaned wood gas to the existing parked engine and generator, with diesel pilot fuel.
20 kWe mixed-fuel point · 23% steady AC efficiency · 25% of fuel energy from diesel.
Requires a qualified engine conversion and verified cooling duty.
Model shared engine →A gasifier and spark-ignition generator run in efficient batches into MSEC’s battery.
6 kWe design point · 24% steady AC efficiency · no diesel pilot.
Adds a second engine, radiator, exhaust and maintenance access.
Model wood genset →Gasification, catalytic cleanup and a solid-oxide fuel cell share an insulated hot train.
3 kWe design point · 35% steady whole-fuel AC efficiency target · no diesel pilot.
Assumes steady hot operation. Compact integration and lifetime are unproven.
Model fuel cell →Machinery targets include 25% packaging growth. Add 1.00 m³ for preparation, robot/dock and fixed clearances, then ready-fuel storage. Every custom envelope is an allocation, not a measured assembly. Existing MSEC hardware remains shared infrastructure.
Interactive system model
Start with the wood you collect. Follow its water, dry solids and conversion losses to net electricity at MSEC’s usable electrical boundary.
Loading the numerical design basis…
After robot, preparation and electrical losses
Machinery + robot + preparation + reserve
Heat is available after drying, if there is a useful demand. Shared-engine heat includes the declared diesel pilot. Full-load heat release includes exhaust; it is not all radiator load.
Equal energy comparison
Each candidate sizes its own collection time.
Packaging and fuel moisture stay the same.
| Architecture | Collection / day | Complete volume | Wood yield | Diesel / day |
|---|
These are conditional allocations at different readiness levels. The smallest displayed target does not establish a buildable minimum. A goal above the machine’s duty limit is shown as unavailable.
Collect, then process
An electric forwarder brings graspable fallen pieces to a guarded preparation station. The first operating mode is supervised or remote controlled.
Autonomous forest cutting is outside this concept. A chainsaw can cut quickly; transporting pieces, searching, loading and terrain set the all-in collection rate.
35 kg payload · 100 m radius
0.4 m/s effective speed · 12 min handling
Round-trip travel plus search, load and unload. Robot charging consumes 1.18 kWh per collection hour. Supply density, slope and failed grasps can reduce output sharply.
A 30 cm × 2 m solid log can weigh 71–99 kg when seasoned. That exceeds the default payload; it needs shorter pieces or a separately rated drag method.
Keep chunking, screening and drying at a fixed guarded dock. Reject dirt, stones and unsuitable wood. Avoid an onboard pellet mill.
Use recovered heat to reach a 15% moisture target. Daily heat balance does not establish dryer residence time. Reserve fuel and stowed equipment remain in the volume budget.
Parked generation, a removable external process module and isolated battery charging. The current 50,000 lb MSEC study provides context; spare bay space, axle loads and engine conversion have not been verified. Producer gas and exhaust stay outside the occupied ventilation boundary, with monitored isolation and controlled shutdown.
What supports the design
Conservation equations are reproducible. Small custom packages, robot productivity and long-lived fuel-cell integration remain engineering targets.
Dry wood contains roughly 5.2 thermal kWh/kg on a lower-heating-value basis. Wet collected mass includes water. The model pays for drying, 10% rejection and processing.
Forest Research ↗The PP30 manufacturer lists two shipping envelopes totaling about 4.43 m³ and 1,497 kg. Shipping size is not installed size, and cannot prove a smaller custom package by linear scaling.
ALL Power Labs ↗FlexiFuel’s over-40% figure is product-gas-to-electricity. It does not establish our 35% whole-wood target. HiEff reported fuel-cell degradation in integrated pilot work.
European Commission ↗Design decisions
This is an analytical screening design. It compares three candidates rather than claiming a universal physical optimum.
Wood is difficult to digest into biogas without extensive pretreatment. Gasification converts prepared wood to a combustible gas directly, making it the selected route for compact electrical generation. Bioreactor is the project name.
Catalytic reforming can turn tar into usable gas and protect a fuel cell. Making methanol or synthetic diesel adds pressure equipment, separation and conversion losses. For electricity beside the vehicle, cleaned gas avoids that extra machinery.
Net wood electricity is after routine generator auxiliaries, a 90% combined charger/storage/inverter path, preparation, dryer fans and robot charging. Wood consumed during start or holding produces no electricity. Shared-engine diesel electricity is listed separately.
Drying consumes 0.9 thermal kWh per kg of evaporated water. Recovered heat serves drying first. Any external heat shortfall is disclosed. The fuel-cell case assumes continuous hot operation and excludes cold-start cycling.
Product-specific CAD, an engine conversion and cooling map, qualified feedstock, dryer throughput, measured robot cycles and fuel-cell lifetime evidence. Complete mass and service access must be reconciled with MSEC’s chassis and electrical architecture.
Collection capacity does not establish a sustainable or permitted fallen-wood supply at one campsite. Equipment, maintenance, delivered fuel and life are unpriced; cost per kWh is not yet established.
Baseline: 35% incoming wet-basis moisture, 15% prepared target, 220 kg/m³ prepared bulk density, 25% machinery packaging growth and two days of ready-fuel reserve. All inputs and citations are available in the public model basis.
Numerical basis & source links ↗Private design and research documents stay in the source repository. The public source hash record supports revision checking.
Design revision hashes ↗