A controller for determining an injection strategy for a fuel injector within a hydrogen fuel injection system within an engine, the controller comprising: an input arranged to receive an engine operating parameter and a pressure signal associated with the pressure of hydrogen fuel available for injection from the injector in the fuel injection system; a processor arranged to determine an injection strategy for the injector in dependence on the received pressure signal and engine control parameter, the determined injection strategy comprising one or more injector control signals to control operation of the fuel injector; an output arranged to output the one or more control signals to the fuel injector.

A method of controlling a dual fuel engine configured to receive a first fuel and a second fuel includes operating the engine using the first fuel, measuring a current load of the engine, sending a first signal to a first fuel system to deliver an amount of the first fuel to the engine, and determining at least one first operating parameter associated with the engine. The method also includes determining an engine load estimate based on the first signal and the at least one first operating parameter, comparing the engine load estimate to the measured load, and based on the comparison, determining, an adjusted engine load estimate to compensate for a drift in the first fuel system.

A method to increase efficiency in a hydrogen fuel system requiring high pressure hydrogen injection and having a plurality of hydrogen fuel tanks, the method including controlling one or more hydrogen fuel tanks and at least one hydrogen fuel tank to provide fuel in parallel to the hydrogen fuel consumer. The method includes determining when an intermediate tank pressure threshold has been reached in all hydrogen fuel tanks. The method includes responsive to the intermediate tank pressure threshold being reached in all of the hydrogen fuel tanks, removing the at least one hydrogen fuel tank from providing fuel to the hydrogen fuel consumer while using one or more hydrogen fuel tanks to provide hydrogen fuel to the fuel consumer. The method includes when an engine brake event has been detected, pumping hydrogen from the one or more hydrogen fuel tanks into the at least one hydrogen fuel tank.

A method of controlling a dual fuel engine configured to receive a first fuel and a second fuel includes operating the engine using the first fuel, measuring a current load of the engine, sending a first signal to a first fuel system to deliver an amount of the first fuel to the engine, and determining at least one first operating parameter associated with the engine. The method also includes determining an engine load estimate based on the first signal and the at least one first operating parameter, comparing the engine load estimate to the measured load, and based on the comparison, determining, an adjusted engine load estimate to compensate for a drift in the first fuel system.

A hydrogen combustion engine arrangement includes a source of hydrogen, an internal combustion engine having at least one cylinder having an inlet opening connected by first hydrogen supply line to the source of hydrogen and an outlet opening, an exhaust aftertreatment system connected by an exhaust line to the outlet opening of the at least one cylinder, the EATS including a selective catalytic reduction system (SCR), a combustion zone upstream of the SCR, the combustion zone being connected to the source of hydrogen by a second hydrogen supply line, and an arrangement for determining a temperature in the EATS, and a computer system configured to control delivery of hydrogen to the EATS in response to a signal from the temperature determining arrangement.