The renewable energy production and storage features, described below, make it possible to safely operate the Green Explorer Vessels for prolonged periods at sea or at anchor in the world’s most remote, challenging and beautiful areas, while the owner, guests and crew enjoy the full regiment of all modern creature comforts – without having to burn any fuel.
Heavy Energy Demands
In “the good old days”, all sailing ships were “zero-emission” – apart from whatever was burned for heating, cooking and lighting purposes. But that was before the arrival of auxiliary engines, electric heating and cooling, electric lighting, radar, sonar, electronic communications, electric/hydraulic steering, computers and entertainment systems, fridges and freezers, bow thrusters, hydraulics, automated sail handling, water desalination, waste water treatment, electric pumps, anchor winches, pressurised freshwater systems and abundant hot water – all pretty much standard equipment on modern super yachts. How then do we manage to sail – and take full advantage of all this equipment on board the Green Explorer vessels, operating in some of the world’s most extreme and beautiful areas – without having to burn any fuel – fossil or otherwise?
Propelled by the Wind
It is not uncommon for a mid-sized, private motor super yacht to burn 1000 liters of fuel and the biggest and fastest will burn up to 18.000 liters – per HOUR… Around 85% of the world’s super yachts are motor yachts, unable to move without burning vast amounts of fuel. In contrast, for most of the time at sea, the Green Explorer vessels move under direct wind power. 980sqm of downwind sails and 420sqm of upwind sails will ensure speeds of up to 14 knots. The sails also dampen the movements of the vessels in heavy seas. Sail handling is fully automated with manual backup systems.
Push-button operated 980sqm sail wardrobe aside, the Green Explorers are directly driven (no gearbox) by a 300kW/550rpm, permanent magnet (PM), electric motor (up to 98% efficiency) and an over-sized, 4-bladed, controllable pitch propeller. This propulsion system has multiple advantages; one is that our electric PM motor has only ONE rotating part and, not using a gearbox, this reduces the chances of a breakdown to only a small fraction when compared to a diesel engine with gearbox. Importantly, the electric motor becomes a variable electric generator, when the propeller is turned by being moved through the water by the force of the wind acting on the sails (see Green Power Regeneration below). Another advantage is the electric motor’s extremely high linear torque available all the way from 0-550rpm. Combined with the controllable pitch propeller, this makes precision navigation in close quarters and controlling “walk” when reversing much easier. Finally, it turns electric “motor sailing” at low wind speeds into a highly efficient, noiseless, pollution-free and enjoyable experience. The Green Explorers will be driven by the wind most of the time. However, when leaving/entering ports or anchorages, navigating narrow channels or inside environmentally protected areas, or in case of calm, the electric motor will drive the vessel in complete silence, powered by the 6.5 tonnes, 220kWh, AGM battery bank for up to 5 hours (8 hours in emergencies) at low speeds.
Green Power Regeneration from the Propeller
The Green Explorer vessels will generate up to 40kW of constant renewable energy, when they are driven by the wind. By adjusting the pitch of the propeller blades away from the neutral horizontal sailing position, the water flow will cause the propeller to rotate the electric motor, which then becomes an ultra-quiet electric generator. This “free” renewable energy will cost up to a maximum of 10% reduction in boat speed. It’s like going down a “never-ending” hill in an electric car and constantly slightly braking it – thus creating energy. Unfortunately – for the electric cars – “never-ending” hills are hard to find.
On the Green Explorers, the system works like this: You are sailing in a moderate wind and plan to arrive in 8 hours at a quiet, beautiful anchorage. Following previous days of anchoring, the 220kWh battery bank now shows 40% discharged, i.e. you need to charge 88 kWh to have the battery bank fully charged. This means that you, on average, should charge 11kW for 8 hours. To achieve that, you simply adjust the pitch of the propeller blades until you reach the right charging level. In the real world there are around 10% charging losses on our AGM batteries (the batteries store 10% less energy than you put into them) and, as you approach the fully charged stage, it takes longer to charge the last 10%. Never-the-less, when you arrive at your quiet, beautiful anchorage, you will enjoy up to four days of silent, pollution-free, functional luxury and full creature comforts. You do not have to listen to a diesel generator, grinding away 24/7 – or suffer the exhaust fumes or vibrations – unless a more conventional, fuel-guzzling super yacht should happen to be anchored next to you! However, this would be highly unlikely in most of the unique places, you could soon discover as the fractional owner and member of the Green Explorer’s Society.
Electric power is also supplied by two silent wind turbines and 40sqm of the latest solar panels. Together, these two technologies provide renewable power up to a rated maximum of 10kW. This is an important source of renewable energy, specially when the vessel is at anchor. When running under sail, the Green Power Regeneration from the propeller will normally provide 10-20 times as much renewable energy as the wind turbines and solar panels combined. Dragon One is equipped with two wind turbines giving a combined maximum output of 4.5kW. They are both state-of-the-art, chosen for their silent operation and tolerance of turbulent wind conditions. They can both survive wind speeds in excess of 200km/h.
The Battery Bank – The Heart of the Zero-Emission System
All the collected renewable free energy, described above, is stored in the 6.5 tonnes, 220kWh, AGM battery bank, which, placed inside the spacious keel area, contributes to the 25 tonnes of lead ballast. We have chosen the well-tested and proven AGM battery technology because your Green Explorer vessel often operates in extreme and remote locations. It is OK to experiment with lithium related battery systems close to civilisation – but when you are out there, far from the nearest assistance, you want something with a long, proven safety record. Our batteries can even be turned upside down and still be fully functional. They are maintenance-free and they do not vent hydrogen, as they re-combine (inside the sealed battery) the small amounts of hydrogen and oxygen created during the very wide “normal” charging tolerances. In the highly unlikely events that batteries become overcharged, several types and levels of alarms and automated shut-down procedures will kick-in, supplemented by available manual shut-down procedures. The energy stored in the battery bank can silently propel the vessels at low speeds for up to 5 hours (8 hours in an emergency). It will also provide sufficient energy to silently run all the “mod cons” equipment on board for up to 4 days at anchor in remote places.
Ultimate Safety: Twice Redundant Emergency/Back-Up Generators
As a final power safety feature, all Green Explorer vessels are equipped with two redundant, 183kW, silenced, variable speed, diesel generators, each of which can function as an independent, emergency/back-up power system capable of running all on-board systems and simultaneously driving the vessel at up to 9.5kn – 11.5kn when combined.
Your Green Explorer vessel is capable of sailing around the world without burning any fuel, the back-up/emergency diesel generators are just that: two extra power safety options.
We are actively researching and aim to replace one or both diesel generators with a number of redundant and reliable ultra-low emission reforming fuel cells in all Green Explorer vessels.
Double Super-insulated Hull
All interior steel surfaces are first blasted to SA2.5+, then, within strict time limits depending on the air humidity, primed and insulated with 4 sprayed layers (2mm) of Delta-T, a super-insulating ceramic coating, which prevents condensation and soundproofs the vessel. Furthermore, by spraying 80mm of flame-retardant polyurethane foam on top of the Delta-T, we create a double super-insulation, making the hull highly sound-proofed and virtually condensation-free. The result is ultra-low energy demands when heating or cooling the interiors – even in extreme climates.
A Global, Zero-Emission, Extreme Explorer Vessel
Although the Green Explorer vessels are specially designed and built to safely explore the high latitudes in both hemispheres, they are equally at home, extremely safe and utterly comfortable in the tropics.
“Price is what you pay. Value is what you get…” – Warren Buffett