(487a) Fuel Processing Activities At European Level: A Panoramic Overview

According to the International Energy Outlook 2011, world marketed energy consumption is growing dramatically, with a worldwide projection rising of 53% from 2008 to 2035, China and India accounting for half of the growth. Expanding energy demand from economic output and improved standards of living will likely put added pressure on energy supplies. On such a context, the European Union’s energy approach, the Horizon 2020 strategy, aims to address energy security, resource efficiency and climate change challenges by reducing the greenhouse gas emissions levels by 20%, increasing the share of renewable energies to 20%, and increasing the energy efficiency by 20%

On this point of view, Fuel Cell (FC) technology and fuel processing (FP) of fossil and renewable fuels are playing a crucial role in future sustainable and distributed energy generation for both mobile and portable applications. Specifically, the employment of hydrogen on FCs technology could ensure significant advantages in terms of efficiency and environmental impact, with reduced production of carbon dioxide, representing thus an important alternative to the conventional energy production systems.

Considering the actual lack of infrastructure for hydrogen production, storage and distribution, equipments operating with FCs fed with hydrogen produced by onboard reforming of fossil fuel to generate power or auxiliary power represent a valid and interesting alternative to overcome such an unfavorable situation. In this context, research and development on several reforming systems for fuel processor units (FPUs) has gained a prevalent role in the perspective of solving these problems in a short-medium term. Moreover, FP is a viable option to meet the limited space demands on board vehicles, specifically for auxiliary power units (APUs).

A FP can be realized in a variety of configurations depending on its final application. The first processing step is accomplished by a reforming reactor, which can be a partial oxidation (POX) reactor, or a steam reforming reactor (SR), or an autothermal reformer (ATR). The H₂/CO ratio in the reformate gas depends upon steam-to-carbon (S/C) and oxygen-to-carbon (O/C) ratios, which are a consequence of the fuel to be processed. Subsequent steps are targeted toward reformate conditioning, as adjustment of the H₂/CO ratio and CO removal. When high purity hydrogen is required to feed a low temperature PEM FC, CO has to be almost completely removed thorough a series of catalytic reactors consisting typically of a water gas shift (WGS) reactor and a preferential oxidation (PROX) or selective methanation (SMET) reactor. Usually, an afterburner (AFB) is present, to burn the hydrogen exhaust gas from the PEM-FC anode and provide thus heat to the system. A series of balance of plants (BoP), such as heat exchangers for the internal heat recoveries, water recovery radiators, air compressor, water and fuel pumps, complete the whole FP [1,2].

Considering small and medium size APU systems, ranging from a few kilowatts to a few hundred kilowatts for both portable and mobile applications, microstructured reactors (MSRs) appear to be very promising for achieving maximum compactness. MSRs typically carry small channels, with dimensions in the submillimeter range, with a high surface-area-to-volume ratio, which reduces diffusive transport limitations. Thus, such a technology offers many specific advantages as compared to conventional chemical reactors: (i) enhanced heat transfer, which may be exploited for highly exothermic reactions with the aim of removing the heat generated and suppressing hot spot formation; (ii) superior mass transfer, which can help to optimally control gas concentration profiles in the reactor by suppressing the mass transfer influence on the overall kinetics as well as enhancing the gas adsorption and desorption phenomena at the catalyst surface; (iii) low pressure drop; and (iv) short residence times. When the reactor plates are coated with catalyst, the heat generated by exothermic reactions (or required by endothermic ones) may be removed (or supplied) by design the reactor as a plate heat exchanger, thus improving the thermal management of the reactor itself. Moreover, another way of exploiting the improved heat transfer is the combination of exothermic and endothermic reactions in a single reactor designed like a plate heat exchanger. Thus, the process intensification benefits of microtechnology for gas-phase reactions are currently within the focus of the worldwide research related to fuel processing [3–5].

Many papers available in the literature examined APU systems both from modeling and experimental point of view. As reforming units, SR, ATR, POX, and thermal cracking (TC) have been considered as possible alternative to reformate fossil fuels. On average, SR-based FPs, as compared to the ATR-based ones, showed higher efficiency and larger hydrogen concentration, notwithstanding a slightly higher process scheme complexity and a somewhat more difficult water recovery. As fuels to be reformed, virtually all of the FFs can be considered, starting from gasoline, diesel, biodiesel, propane, and CNG: on average, considering the commercial liquid FFs and by maintaining the same net power released by the APU, the overall efficiency decreased following the rank gasoline, light, and heavy diesel. This is mainly linked to the hydrogen-to-carbon ratio HCR of each fuel: the higher is this ratio (gasoline > light diesel > heavy diesel), the higher is the APU overall efficiency [3,4].

From a technological perspective, actually PEM FCs still need to be considerably improved before penetrating automotive market. Moreover, even considering the doubling of hydrogen refueling stations in Europe in four years, a widespread hydrogen infrastructure does still not exist today. Based on these considerations, reliable, efficient, and quiet APUs are becoming the early market for recreational applications (caravans and yachts), for mobile telecommunication industry (back-up and UPS systems), and for material handling vehicles market (forklifts), with robust commercial products available for business.

The present manuscript provides a panoramic overview of the most recent work carried out at a European level on the research and development of fuel processing technologies for fuel cells. Moreover, an update on actual existing commercial products manufactured in Europe is provided (Helbio, Greece, Truma Gerätetechnik, Germany; UPS, United Kingdom; EPS, Italy; Hygear, The Netherlands).

[1] Cutillo A., Specchia S., Antonini M., Saracco G., Specchia V. J. Power Sources 154 (2006) 379–385.

[2] Kolb G., Cominos V., Hofmann C., Pennemann H., Schurer J., Tiemann D., Wichert M., Zapf R., Hessel V., Lowe H. Chem. Eng. Res. Des. 83 (2005) 626–636.

[3] Specchia S., Specchia V. Ind. Eng. Chem. Res.49 (2010) 6803–6809.

[4] O’Connell M., Kolb G., Schelhaas K.-P., Wichert M., Tiemann D., Pennemann H., Zapf R., Chem. Eng. Res. Des. 90 (2012) 11–18.

[5] Kolb G., Chem. Eng. Proc. Process Intensification 65 (2013) 1–44.