Strategy: Battery-powered tugboats with auxiliary solar barges

Solar, wind, and/or battery-electric tugboats for large barges

The idea: develop a marine vessel that is a mobile floating solar and/or wind power plant. Solar panels are the cheapest sources of power in the world, why rely on shore power? The financing and environmental impact models are based on a plan of simply replacing the fleet of diesel tugs pulling log barges around Vancouver Island, and never expanding to other applications. See Future Work at the bottom of this page for potential expansions of scope.

Throughout this page, the phrase "megaCAD" is used to mean millions of Canadian dollars. It's a known issue with the way I'm tracking units: mega is the scientific prefix for millions, and CAD is our currency.

Summary

Key assumptions:

Log barges typically carry between 10_000 and 15_000 tons of logs, and self-unload
Pacific log tugs pull barges of logs between 200 and 600 km, and return empty.
Such tugs typically burn 400 l/hr while underway.
Tugs typically cruise with 2000 hp, can provide up to 5000 hp.
Batteries alone cannot make the trip (in truth, they might be able to within a few years)
Budget per battery-powered tug: 8.38912355530054 megaCAD
Budget per auxiliary vessel: 0.25192749036867024 megaCAD
n. auxiliary vessels required per tug: 10
Vancouver Island solar energy per day in winter: 1.3 hour * kilowatt / day / meter ** 2

Key predictions:

Net Present CO2e @ 2.0%: -3190.919 kiloton (negative means reduction)
Net Present Heat @ 2.0%: -1.315 exajoule (negative means reduction)
Net Present Value @ 2.0%: 974.563 megaCAD (negative means non-profitable)
Net Present Value @ 5%: 235.473 megaCAD (negative means non-profitable)
Net Present Value @ 10%: 44.908 megaCAD (negative means non-profitable)
Cost per removed/avoided tonne CO2e: -336.67 CAD / metric_ton

Impacted IPCC Sectors:

Transport/Marine/Domestic_Navigation: (TODO: table with what amounts / percentages on various horizons)

Walkthrough with Graphs

Suppose that the fleet size is constant.

Suppose that the number of ZEV vessels increases linearly at a steady rate sufficient to replace the fleet every 20 years.

The impact on CO2 emissions from the Pacific log tug fleet is expected to be significant.

The impact on atmospheric CO2 concentration is expected to be very small. That said, if the technology used in this solution were scaled globally, the impact could be significant. (TODO: estimate how significant)

A visualization of the difference in global heat forcing reveals the shape of the impact over time. The datapoints in this curve are used to compute the Net Present Heat for the project, by adding up the energy associated with each year (modulated by the future discount factor).

In other terms, the difference in global heat forcing can be quantified as a small change in (upward) temperature trajectory for the top 200m of the world's oceans.

In terms of financial modelling, the project is modelled as

needing 1.0 megaCAD / year for research, development, and operations,
needing 10.908398458987241 megaCAD per vessel [set] a rate sufficient to replace the fleet over vessel lifetime of 20 year
earning 3.458367123287671 megaCAD annually per vessel [set] in saved fuel

Future Work

Extend to model the use of vessels for Great Lakes freight (tow "Lakers")
Extend to model the use of vessels for stationary power generation on lakes and ocean coasts
Extend to model the use of vessels for international freight, power generation (i.e. where there's more sunlight)
Model how much additional power could be generated by wind by sails or turbines. How would it change the performance characteristics of the vessels, might it be worthwhile?
Formalize product, estimate pricing, refine manufacturing and operating costs