Abstract
The development of alternative technologies is crucial to mitigate emissions of greenhouse gasses, especially in the transport sector, which is largely dependent on fossil fuels. Considering this, biorefineries are playing a pivotal role in the generation of value-added products, such as biofuels, green hydrogen (H2) and green ammonia (NH3). These compounds have potential to be applied in the industrial supply chain or across different sectors, particularly in mobility. Hydrogen stands out for its impressive gravimetric energy density, being a strong candidate for the future of mobility. However, H2 compression requires a high energy demand and pressure over 700 bar, which is challenging for safety reasons. To circumvent this issue, the use of hydrogen carriers, such as green ammonia, is proposed as a solution. In this scenario, NH3 is reformed in a reactor to produce H2 onboard, which is sent to a fuel cell to convert H2 into electricity. Even so, it has been unclear which process is more efficient: either green H2 production and compression or green NH3 production and its reforming for on-site H2 generation. Therefore, this paper presents the theoretical evaluation of the energy efficiency of both systems, using Aspen Plus® Software. Considering that both processes start from sugarcane bagasse gasification, the system of H2 compression required less energy and showed a slightly higher H2 output than onboard production. Through a sensitivity analysis, it was seen that NH3 reforming is maximised at 1 bar and high temperatures. In the future, it is possible to improve the green NH3 system to become more competitive.
