Hydrogen will soon be extensively applied in distributed systems of energy production that use new, reliable and sustainable hydrogen fuel cells to produce clean energy 24 hours per day, 365 days per year to meet the demanding needs of apartment blocks, office buildings, stores and neighborhoods. Recently, the US company Bloom Energy has installed
Figure 4.18 A Bloom Energy “Energy Server’’ uses SOFCs to produce enough power to account for the entire energy demand of a typical office building. (Reproduced from Ref. 21, with kind permission.)
several newly developed solid oxide fuel cells (SOFCs) at a dozen large US firms that now self-generate electrical power from natural gas (Figure 4.18).23
Bloom’s fuel cells can flexibly use any fuel, including bio – or natural gas, ethanol and, of course, hydrogen. Thanks to a 30% federal tax credit, they produce silent, low-emission power for less than c$10 per kWh (ten cents per kilowatt-hour), much the same as a combined-cycle gas-turbine plant, but without the noise and fumes.24
The so called ‘‘Energy server’’, the self-contained generating unit, costs around $750 000 per 100 kW block, and, like other SOFCs, makes use of a common sand-like powder instead of precious metals like platinum or corrosive materials like acids. It operates at a high temperature (typically above 800 °C) which gives it extremely high electrical efficiency and fuel flexibility, both of which contribute to better economics. However, it also creates engineering challenges that were solved by the company with prolonged financial back-up ($400 million) of venture capital, which started in 2002. The result of this R&D effort was a 25 W fuel cell (Figure 4.19) that makes distributed generation so reliable that the company offers customers the opportunity to purchase the service (clean electricity) for 10 years in place of the product (the Bloom Box), thus avoiding the initial investment and giving immediate cost savings.
Figure 4.19 The fuel cell developed by Bloom Energy is made of thin white ceramic plates (100 x 100 mm). Originally introduced in the late 1990s by K. R. Sridhar and his team at the University of Arizona as part of the NASA Mars space program, these SOFC were later developed by Bloom Energy. (Reproduced from Ref. 21, with kind permission.)
Each ceramic plate is coated with a green nickel oxide-based ink on one side (anode) and another black ink (probably Lanthanum strontium manganite) on the other side (cathode). The electrolyte materials may include a scandia-stabilized zirconia (with higher conductivity than yttria-stabilized zirconia at lower temperatures), which provides greater efficiency and higher reliability when used as an electrolyte in SOFC applications.25
Adding another revealing clue to the silent and yet powerful shift occurring in industry, from polluting technology to cleantech, in 2011 Bloom Energy purchased from the automaker Chrysler a former car manufacturing factory in Newark, Delaware, which was closed down during the 2008 recession. The factory is currently being repurposed and will eventually manufacture 30 MW modules using its SOFCs.
Innovation in fuel cell technology and solar hydrogen is rapidly occurring in several countries. In Italy, Electro Power Systems has developed a self-recharging back-up power system (ElectroSelf, Figure 4.20) that overcomes one of the biggest obstacles to mass deployment of fuel cells, namely the sourcing of hydrogen.26
The system uses an electrolyzer and a PEM (proton exchange membrane) fuel cell to minimize the mismatch in energy production and consumption by efficiently storing energy from the grid or when renewables are plentiful, and instantaneously releasing energy whenever
Figure 4.20 By simply adding water to the ElectroSelf, the system self-generates hydrogen fuel using electric power from the grid or from PV solar or wind energy. It releases energy instantaneously when there is a power dip or outage.
(Reproduced from Ref. 24, with kind permission.)
renewables are weak or absent. As such, the system is able to ensure a steady power supply for virtually any application, ensuring always-on power and connectivity. By late 2011, over 600 ElectroSelf fuel cell power systems had been installed in Europe, Asia, Africa and the Americas.
To get an idea of the environmental and economic relevance of this fuel-cell technology, it is sufficient to remind the reader that currently there are about 5 million telephone communication towers in remote, off-grid locations that, continuously needing power, rely on either diesel generators or solar PV panels coupled to lead batteries. The ElectroSelf – which was redesigned in 2011 to be smaller and more efficient, with higher performance and enhanced flexibility – is logistics-free and drastically reduces the economic and environmental economics of back-up power provision. Customers can get rid of batteries and diesel generators, and thus eliminate the costs of fuel logistics and heavy maintenance, as well as the fossil fuel price uncertainty.
Similary, BOC has recently introduced to the portable power market its Hymera hydrogen fuel cell generator,27 which can provide up to 200 W of off-grid DC power (Figure 4.21). When coupled to a portable hydrogen cylinder, the Hymera DC can provide 2-3 kWh of energy. Cylinders can be manifolded together for much longer run-times. Again, water vapor is the only by-product and operation is near-silent, making
Figure 4.21 The Hymera generator runs on hydrogen and is supported by a lightweight hydrogen cylinder. This package has an integrated regulator, making it simple and easy to use. When full, the cylinder package weighs approximately 10 kg.
(Reproduced from Ref. 27, with kind permission.)
these generators ideally suited for applications where the emissions from diesel or petrol generators could become a problem, or where noise is an issue. Applications include portable power applications and those that need to operate continuously for long periods of time, such as security cameras, environmental monitoring, wireless communication systems and back-up power for communications systems.