Solar-Reports:


Fuel Cells and Solar Hydrogen-
A Power Package for the Future?

by Rolf Hug
16.10.2000

Renewable Energy is highly appreciated right now. Sun, wind and water are not only highly valued on the stock market: drivers, house owners, and renters have become reflective due to rising energy prices and are looking around for alternatives. It's a good time for visions, in which the fuel cell is standing more often in the spotlight.


The Principle: Electricity from "Cold Combustion"

The idea is actually quite old. The physicist William R. Grove discovered the technology as early as 1839, which was used for space travel in the 1960s to produce water and energy for the crewed space flight: the fuel cell.

Functionale Principle of the Fuel Cell

The principle is not altogether too complicated: the fuel cell works like an inverted electrolysis. Instead of dispersing the chemical components of water (hydrogen and oxygen) through electricity, direct current is produced and water is obtained in the form of steam.




Illustration: Vaillant-Gruppe

Hydrogen and oxygen react in the fuel cell and bond into water over a thin, permeable membrane. Energy is freed, through this process, in the form of electricity. The fuel cell, therefore, transforms the chemical energy of the oxidation process, the so-called "cold combustion", directly into electric energy. The only by-product is steam.

If the needed hydrogen could be obtained through solar energy, this secondary energy source would become an important alternative for the power supply of the future: environmentally friendly and pollutant free. Hydrogen is, however, not a source of energy, it just carries and stores energy. And the fuel cell is not a Perpetuum Mobile (an object that continually moves without energy input), but technology through which electricity can be produced-nevertheless with remarkable efficiency: the heat obtained through electricity production can be used to heat, just as with a block-type thermal power station.

The Technology: Fuel Cells for Cars and Heating

Not only drivers and heating oil consumers are hoping for an alternative to ever more expensive fossil fuels. Large oil companies, such as Shell and BP, and power companies are drawing more strongly on regenerative energy and are looking for subsidiary solutions.

 

The leading automobile producers, with DaimlerChrysler at the front, and the heating system company Vaillant want to deliver market-ready fuel cell products in the next few years. BMW wants to equip a number 7 sedan with an engine that burns hydrogen rather than gasoline. The researchers from the Volkswagen Corporation, along with Ford, General Motors, Honda and Toyota, are working on concepts where hydrogen will not be produced until during driving. DaimlerChrysler wants to offer, within the next three years, production ready A-Class automobiles as well as "Citaro" city buses with this new technology. The Daimler Fuel Cell Project is cooperating with the Canadian manufacturer Ballard Power Systems. The worldwide market leader for proton exchange membranes (PEM) develops and delivers fuel cells for transportation, power supply, portable equipment and further uses.

Fuel Cell: Core

The proton conducting membrane is the core of the fuel cell.
Illustration: DaimlerChrysler

NECAR 4: A Mobile Power Station In Front Of the House

Drive quick, clean and quiet- without a bad conscience? The dream of the environmentally conscious driver appears to be becoming a reality. DaimlerChrysler already presented the New Electric Car 4 (NECAR IV) in the USA in early 1999, a fuel cell automobile with a large range and good mileage in an A-Class Mercedes. The fuel cell, the tank and room for up to five people with luggage have found, for the first time, space in a compact car. Just a few years ago, the mobile fuel cell technology would have needed a large vehicle.

Fuel Cell Automobile "NECAR 4"
Illustration: DaimlerChrysler AG

NECAR 4,
the first fuel cell automobile suitable for daily use.

A-Class with Fuel Cell Propulsion
Illustration: DaimlerChrysler AG

The "sandwich floor" in the A-Class is the platform where the fuel cell propulsion is installed.


The NECAR 4 runs on liquid hydrogen; the tank is located in the back of the vehicle.
A proton-conducting fuel cell (Proton Exchange Membrane Fuel Cell- PEMFC) processes the fuel. A platinum plated membrane disperses the hydrogen into protons and electrons. Water is formed through contact with atmospheric oxygen. Positive and negative poles are formed by the surplus or shortage of electrons and protons; the electric motor, which powers the vehicle, is connected through this. One tank-up should last up to 450 kilometers.

Project manager Prof. Dr. Ferdinand Panik also envisions a business opportunity in the expansion of the technology: "The fuel cell activities are no longer driven by technology or are influenced by environmentalism, but depict, in the meantime, a real competition factor," stated Prof. Panik at a press conference in Stuttgart. " We recognize the fuel cell as a business opportunity to secure high tech jobs and company success." He projected, in SPIEGEL magazine, the vision of an "Energy Internet" that is made up of interconnected fuel cell cars. The "mobile power station" could stand in front of the house or in the garage and deliver about 75 kilowatts of energy, of which only 3-10 kilowatts would be used in the household. The rest would be fed into the electricity network.

Fuel Cells in the Cellar: Heating Systems from Vaillant

The Vaillant Group, one of the leading European producers for heating technology, wants to bring their new fuel cell heating unit onto the market as early as the year 2002. The company has already been working for two years on the integration of the technology into the household heating system. The heating of residences should, in the future, deliver electricity and heat at the same time, reduce primary energy consumption and greenhouse gasses, and also contribute to the safeguarding of the power supply. Vaillant goes a step beyond the well-known block-type thermal power plant to the local energy supply and brings the technology to the final consumer.

Fuel-Cell Heating Unit

Illustration: Vaillant-Gruppe

Electricity and heat can be produced in a linked process with fuel cell heating units in almost every building that has a gas supply.
The pure CO2-free hydrogen for the PEM-fuel cell will be obtained from natural gas through a so-called reformer. The electrical efficiency of the heating unit will amount to approximately 35-40%; an entire efficiency of 80% will be reached through the power-heat coupling. The waste heat from the fuel cell will be used for heating and warming of domestic water. On especially cold days, an integrated conventional boiler will cover the remaining demand

The Vaillant heater can also be environmentally persuasive in comparison to the traditional low temperature boiler and electricity from the socket. The fuel cell heater uses low-carbon natural gas and the waste heat too, and thus reduces CO2 emissions by up to 50%. If the climate goals of the European Union are reached, the fuel cell can play an important role in this field. If mass production begins soon, then the hydrogen will still be obtained from natural gas. Solar hydrogen, produced via electrolysis with Photovoltaic electricity is, in and of itself, still the dream of the future for the engineers from Vaillant. It certainly sounds good, since there would always be an emission-free energy source available.

Fuel Cell: Energy and C02-Balance

Graphic: Vaillant-Group

The Future: Sun and Hydrogen in the Solar Global Economy

The new technology is awakening many hopes that still have to be fulfilled. Cars and heaters are not yet available; the final price for the product is at this time incalculable. How much the fuel cell powered A-Class will cost is still unanswerable, as well as the question on nationwide maintenance with fuel. That the technology is still, in some part, in an early stage of development, is especially exhibited with the cars: many manufacturers are competing here, and it is not yet settled, which standards will prevail.

Even when the developers have mastered technological risks such as explosion hazards, there are still a few questions to clear up. The methods of storage, transportation and distribution of the initial substance have to be tested to see if they are environmentally harmful. Methanol, for example, one of the chemical bonds obtained from hydrogen, is corrosive, highly poisonous, and mixes easily with water. If the hydrogen is obtained from gasoline, OPEC will be all the more pleased. If the electricity stems from coal-fired power stations, then the atmosphere will be burdened with more CO2.

At this time, the production costs of solar hydrogen can only be roughly estimated: if it is obtained through large PV systems (300 MW electrolysis), a cubic meter will cost, in the least expensive case, about 2.90 DM, which corresponds to a kilowatt price of about 85 pfennigs for electricity from fuel cells. Produced in small industrial systems, a kilowatt-hour will cost up to 1.70 DM. Only after mass production of PV modules has been expanded, and with it the associated lowering of prices, could Photovoltaic produced hydrogen be offered as an economical solution. The scenarios of large-scale use, which were developed in the 80s, are firmly rejected by Professor Panik and others. Since then, gigantic solar farms in the Sahara are seen by many as the wrong method. The DaimlerChrysler project manager places more value on wind or water power. The latter produces not only electricity, but also hydrogen via electrolysis. Decentralized solutions, such as the Vaillant heater, fit better with solar energy.


Herman Scheer, German Member of Parliament and 1999 winner of the Right Livelihood Award (the Alternative Nobel Prize), also votes for decentralization. He characterizes the global energy industry of the future through the phasing out of fossil sources: they should be replaced by small-, mini-, and micro-power stations.

Solar heat, photovoltaics, and fuel cells have something in common: they are best suited for direct consumer use. Transportation costs and losses will drop. Solar heating systems and domestic Photovoltaic systems are a first and, as of today, feasible step. Fuel cells and solar hydrogen are a consequential continuation-and an important chance for climate politics.

We would like to thank Professor Jürgen Garche from the ZSW- Electrochemical Energy Storage and Energy Conversion Division in Ulm for his assistance in calculating the costs for the production of solar hydrogen.

Translation: Mary Meier

Scheer: Solare Weltwirtschaft

Hermann Scheer analyses fossil resources politics and describes the path to a solar world economy, that should lead to an "ecological modernity"

Illustration: A. Kunstmann Publishing Company

This might be also of Interest: Fuel Cell Research and Development in Southern Germany: Institutes and Companies Forging Ahead into the Future

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