The environmental problems of the hydrogen economy

The environmental problems of the hydrogen economy

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By Jorge Fernández Porto

Considering that with current photovoltaic technology in Puerto Rico we can generate about 40 watts per square meter, 3.9 million strings would be required to generate this electricity. Therefore, it would be necessary to build a second floor (or roof) to the island and not have another use on the surface in order to generate the electricity necessary to produce the hydrogen that would move our vehicles.

In recent months we have heard from one of the candidates for governor, several proposals that have profound environmental impacts, as well as economic and social ones. As the political organization that proposes them describes itself as an environmentalist party, I think it necessary to elaborate a little on these proposals, starting with:

The hydrogen economy.

Rogelio Figueroa tells us that one of the ways of "energy self-sufficiency" that he proposes is to produce hydrogen to replace the gasoline that our motor vehicles consume today. It indicates that this measure would prevent the departure of $ 4 billion from the country, thus generating economic growth.

Now, what is this hydrogen matter that Rogelio never manages to explain in much detail about? In 2003, George W. Bush announced and launched his "Hydrogen Fuel Initiative" into the political arena, a proposal that has Governor Arnold Schwarzenegger of California as one of its first and most enthusiastic promoters. Thus, from a Bush initiative, and not from scientific research or the push of environmentalists, the hydrogen movement arises as an energy panacea. In 2005, the energy policy of the United States was transformed with the Energy Policy Act, which proposes to develop hydrogen, fuel cells and the physical and technological infrastructure necessary to make the use of hydrogen as a fuel for electricity practical and cost effective. year 2020. In other words, the use of hydrogen as a substitute for gasoline is still an experimental process that has not managed to overcome serious technological obstacles, as we will see later.

What is the principle behind the proposal?

Rogelio and those who think like him tell us that the production of hydrogen "is the answer to the high prices of gasoline. It consists of substituting imported gasoline in our cars, with hydrogen produced locally from renewable sources. The goal is to eliminate the Puerto Rico's dependence on gasoline and leave in Puerto Rico, in the form of investment and jobs, the over $ 4 billion that leave Puerto Rico annually for the purchase of gasoline. As a result, Puerto Rico will have a whole new generation of automobiles and machinery that use hydrogen as an energy source "(Taken from the PPR electoral program)

The first problem with the proposal begins with the first three sentences of the proposal. The second law of thermodynamics teaches us that it takes more energy to break down a molecule than to make it.

The entire proposal for the use of hydrogen is based on the production of this element for later use in a fuel cell. Rogelio proposes that we break the water molecule for these purposes. Renewable energy would be used, he tells us, to divide water into its atomic components, hydrogen and oxygen, through a process known as electrolysis, and then use hydrogen and the electrons associated with it.

Here begin the conceptual and practical problems of Rogelio's proposal. For every 1 kilowatt hour of hydrogen we produce, we need 1.3 kilowatt hours of electricity to produce it. Since the goal is to replace imported gasoline, and we import a billion gallons of gasoline per year, we have to calculate how much hydrogen we need to produce to achieve this.

It turns out that 1 gallon of gasoline has 17 times the energy capacity of the same volume of hydrogen [1]; therefore, to replace the gasoline imported to the island, we would need to produce 17 billion units equivalent to a gallon of gasoline [2]. This amount of hydrogen, computed in kilowatt hours, requires 629 gigawatts (629,000,000 kilowatts) for its production Considering that with the current photovoltaic technology in Puerto Rico we can generate about 40 watts per square meter, 3.9 million strings would be required to generate this electricity . Therefore, it would be necessary to build a second floor (or roof) to the island and not have another use on the surface in order to generate the electricity necessary to produce the hydrogen that would move our vehicles.

However, Rogelio's problem does not end here. One thing is the production of hydrogen, another thing is its transportation, storage and use. Each of these actions also involves the investment of energy. For example, to obtain the energy equivalency of a 15-gallon tank of gasoline, a tank with 270 gallons of hydrogen gas is needed. [3] As a tank of this volume would be impractical, the next step should be to bring the hydrogen to its maximum viable density potential, which is to liquefy it (turn it into a liquid) .This action requires even more energy, approximately 30% of the potential energy contained. in the hydrogen to liquefy.

The liquefaction takes us to a 60 gallon tank of liquid hydrogen to store the energy equivalent to a 15 gallon tank of gasoline.

Since hydrogen is not a source of energy, but a transmitter of it, we cannot merely use it directly from the tank in the injectors of vehicles. You have to use it to accumulate charge in batteries and turn your car into an electric one, or a hybrid one. Consider how big your vehicle will be if you have to add a tank equal in size to four tanks you currently have, plus space for batteries, inverters, and other necessary equipment.

Hydrogen has physico-chemical characteristics that do not make it, say, very safe. It is 10 times more flammable and 20 times more explosive than gasoline. Therefore a vehicle accident with a 60 gallon tank filled with hydrogen can cause an explosion that releases 1200 times the energy that would be released in a similar accident with a normal gasoline vehicle.

The environmental consequences of the hydrogen economy that Rogelio proposes to us are enormous. For example, we would need to generate an additional 1,723 megawatt hours per day to just produce the hydrogen needed to replace the gasoline we consume. This production means increasing the current daily electricity generation by 50% during peak hours, or peak hours. We have shown that at least with current technology, it would be impossible to generate this electrical energy with photovoltaic technology, and we do not have enough places with the appropriate wind conditions to generate it by wind means. Therefore, the burning of fossil fuels in power plants should be increased to reduce the burning of fossil fuels in vehicles. To top it all, for every trip a gas tank truck has to give to the garage to fill the tanks, the equivalent amount of hydrogen would have to be served by 17 trucks.

This contradiction can be aggravated. Of the 236 hydrogen serving stations around the world, only 10 of them produce hydrogen from water. They produce the rest from gasoline or natural gas, which are hydrocarbons after all. In fact, the extraction of hydrogen from gasoline is the type of vehicle that manufacturers propose for the future. Incidentally, these hydrogen filling stations are almost all in California - remember that Governor Schwarzenegger is one of the main promoters of hydrogen use - and almost all are demonstration projects and belong to motor vehicle manufacturers.

The economic consequences of the hydrogen economy are considerable. The costs of transforming gas stations to hydrostations; the transformation costs of the same vehicles; the increase in electricity production to generate hydrogen; the costs of a new generation of tanks, since hydrogen is so small that it escapes through the molecules of the materials that try to contain it; all this points to billionaire sums.

In short, fuel cells promise to be a cleaner way to use hydrogen to generate mechanical energy in the perhaps not too distant future. At present, the perception of hydrogen as an energy option is much more appearance than reality and its costs much greater than its benefits.

[1] It is of fundamental importance to know that hydrogen is not a source of energy, but rather a transmitter of energy. Hence the abysmal difference in energy capacity compared to gasoline, which is a source of energy.

[2] Each gallon of gasoline has the energy equivalent to 37 kilowatt hours

[3] The fundamental reason why there is such a big difference between the energy potential of gasoline and hydrogen is that hydrogen, contrary to what the candidate for governor of the PPR indicates, is not a source of energy, but an energy transmitter.

Jorge Fernandez Porto Environmental Advisor of the Puerto Rican Independence Party (PIP) - Puerto Rico

Video: Can Hydrogen Fuel the Worlds Fast-Growing Energy Needs? WSJ (July 2022).


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