Wednesday, June 19, 2013

Hydrogen - efficiency

With hydrogen, there are different types of efficiencies. There's the efficiency of producing the hydrogen and there's the efficiency of using the hydrogen. Let's first examine how hydrogen can be used in fuel cells. Since fuel cells generate electricity through a chemical process, they are not subject to the Carnot Limit (the theoretical limit on engine efficiency based on the flow of heat between two reservoirs). Fuel cells, in combination with electric motors, can achieve an efficiency of 70%, while the 30% that is lost can be used to heat up the car, the house, the hot water system (depending on where the fuell cell system is located). By comparison, internal combustion engines (as used in traditional cars, mowers and mobile power generators) only achieve efficiencies of around 30%.
The image accompanying this article is an example of such a combined system, in this case a Siemens 125kW fuel cell system that supplies both heat and electricity. It's now in its pre-commercial stage, after a 100 kW prototype system has operated successfully in the Netherlands and Germany for over 20,000 hours.
In terms of efficiency, the production of hydrogen does require a lot of energy, indeed it will take more electricity to produce hydrogen than the electricity that hydrogen will deliver as output. After all, some loss will always occur in any production process. so that may not look very efficient at first glance. Nevertheless, this situation can be mitigated by carefully selecting the time of producing the hydrogen. An intelligent system can use surplus energy from renewable sources, such as solar power at midday when the sun is at its peak and when demand is low, or wind power when there is more wind than the electricity grid can handle. The beauty of hydrogen is that it can be produced cheaply at times when there is an abundance or a surplus of energy supply. 
The distributed use of power that is possible with hydrogen also compares well with the centralization that comes with plants that are powered by fossil fuel. Coal-fired plants can be less than 30% efficient, which means that they require huge amounts of water to cool down. Such plants cannot be stopped and started at the switch of a button, but they require long lead times daily to achieve their peak and they cannot be turned off completely. Even when such plants are supplemented by more expensive nuclear or oil-based plants, and despite all the planning of interconnected grids and all the forecasting of peaks, electrical grids still experience black-outs because they cannot handle the peaks.
So, in the distributed model, there will be numerous points where electricity is generated, e.g. by solar panels on roofs, by thermal solar plants, by wind turbines in backyards and by larger wind turbines in the fields. Each of these points could produce hydrogen, while hydrogen can be easily kept and transported to be used when and where needed.
Efficiency relates to the question what is the most economic choice. Free markets are best in working out the when and where, but for free markets to work well, there must be customer choice, entrepreneurial freedom and easy access to technology and entry to the market for new suppliers, all of which is hard in a centralized model. Currently, the associated environmental and security costs aren't well reflected in he supply of fossil fuel. If we further take into account the efficiencies resulting from a more distributed model, hydrogen becomes even more economic in comparison.
[originally posted September 19, 2007]
Comments (added in the course of 2007)
The amount of land needed to produce solar power varies strongly with the amount of sunshine the area receives and the performance of the equipment used. The solar panels that are typically installed on the roofs of houses, offices, garages and car-covers do require relatively large areas, but that is no problem since these roofs aren't used for anything else, so they might as well cater for the energy demand of the building and the cars. But concentrated thermal solar power (CTSP) installations can achieve much higher yields. In deserts, where sunshine is strong and continuous, we can expect the highest yields. One study into CTSP calculated that an area in the desert of 254 km² would theoretically suffice to meet the entire global demand for electricity for 2004. By comparison, the City of New York covers 830 km². 

Similarly, the output of wind turbines varies a lot with the size of the turbine and their location. Note that wind turbines can easily be combined with agricultural use of the land and compliment solar power as their output can continue after sunset. 

More continuous are hydro and geothermal power. Some argue that it would be cost-efficient for geothermal power from Iceland to provide electricity to continental Europe. There is a proposal is to drill 3.8km through the Earth's crust into the hot basalt below Iceland, in order to tap into temperatures of up to 600C and generate enough geothermal electricity to power up to 1.5 million homes in Europe. Electricity would be transported over a 1,200-mile long ocean-floor cable to connect to Britain's national grid before reaching Europe's continent. 

The Grand Inga power station, a proposed hydropower dam in the Congo River, will have a planned output of 39 gigawatts, twice the power of China's Three Gorges, which currently is the world's largest dam.

There is enough clean and renewable energy in the world to meet all our demands. If only we could harness a fraction of the energy contained in thunderstorms, we could easily meet all the energy demand of the world.
Energy efficiency of, say, 25% would more than suffice, given the abundance of clean and renewable energy (see my comment above) and given that hydrogen can be produced in a distributed way using surplus energy from solar and wind power (as the article explains). Moreover, it would be preferable to the current dominance of fossil fuel, in the light of environmental, economic, health and political considerations. Nonetheless, as the article also points out, free markets are best in working out the when and where.
Rather than from natural gas, it's more likely that hydrogen will be increasingly produced from water, by means of electrolysis, using electricity from clean and renewable sources such as solar and wind power, since this wouldn't add greenhouse gases. In cars, I do foresee that fuel cells will compete with Lithium-ion batteries for many years. As I see things develop, the internal-combustion engine in cars will be gradually replaced by hybrids such as the Prius, by plug-in hybrids and eventually by electric cars that run entirely on Lithium-ion batteries, such as the Tesla. 
Simultaneously, there will be a growing market for both fuel cells and Lithium-ion batteries, in order to store surplus power from wind and solar for household and industrial use. Once mass-produced, prices, size and weight will come down for both of them, while their capacity and performance will increase. Just look how the battery in your cellphone now is a lot lighter, smaller and lasts a lot longer than it did only a few years back. Nevertheless, Lithium-ion batteries will remain at a disadvantage, since recharging returns the battery only just under its previous charged state, so the battery will deteriorate over time. Consequently, I can see the Hydrogen Economy emerge well within two decades.

On the issue of safety, it should be noted hydrogen is lighter than air and diffuses in air quickly, which makes it safer than most fuels. Well-constructed containers should prevent leaks, but if leakage nevetheless occurs, the hydrogen will move up and away from the source of the leak. If the hydrogen subsequently inflamed, the risk of the container itself exploding is much less than in the case of a petrol tank leak, since the hydrogen will immediately diffuse into the air. Also, the heat resulting from burning hydrogen is significantly less than heat from burning oil, natural gas or gasoline. Safety considerations are perhaps best discussed in a separate article, such as Steve's excellent article (which should be credited for discussing all these safety points) at:

On safety, read the excellent article about how the Hindenburg caught fire in 1937, at:

Let me also draw attention to the journal of this association, appropriately called Hydrogen Today, at:

Hydrogen-driven cars are indeed available today, have a look at:

Remember what Governor Arnold Schwarzenegger said back in 2004: "An early network of 150 to 200 hydrogen-fueling stations throughout the State (approximately one station every 20 miles on the State's major highways) would make hydrogen fuel available to the vast majority of Californians. Studies show that California's Hydrogen Highway Network is achievable by 2010 and will help demonstrate the economic and technical viability of hydrogen technologies. The California Fuel Cell Partnership and others estimate that this initial low-volume fueling network will cost approximately $90 million, the majority of this funding coming from private investment by energy companies, automakers, high-tech firms, and other companies."

Nuclear: no insurance company is able to cover the risk of accidents and terrorist attacks. The cost of safe and healthy decommissioning of plants and processing and storage of all the waste material is hugely underestimated, all because government writes out blank checks to cover future expenditure. Training of the necessary staff, scientists and military experts is hugely subsidized. The list goes on and on. The huge costs and risks associated with nuclear power drawrf the those associated with hydrogen. 

Nuclear requires an army of well-educated specialists to operate the facilities, to check for leaks, to monitor waste, to draft legislation and standards, etc. This in turn requires entire departments of universities to devote all their energy and attention to educating such people, to do the necessary research, etc. Such universities will in turn support the nuclear alternative simply to obtain further educational funding. All this creates a world that depends entirely on politicians supporting the choice for nuclear. Nuclear plants cannot be built a little bit, they require a long-term decision to commit huge amounts of resources and long-term funding, staffing, supervision and policing of everything associated with it, including risks of terrorism, proliferation of nuclear technology, cleaning things up, etc. As a result, nuclear power goes hand in hand with centralisation, favoratism, corruption and making political deals, producing a society that nobody wants, but that is purely the result of the (wrong) choice for nuclear. 

Even if we (quite rightly) abolished nuclear plants today, we'd be looking after decommisioning plants, storing waste and terrorists seeking to get their hands on radi-active material for decades, which is a cost that is typically and conveniently left out of the picture by those supporting the nuclear alternative.

By contrast, people can hook up their hot-water-systems to solar power in their backyards or put up a wind turbine themselves with little need for specialist training and with little risk to society at large. Solar power alone could well cater for the energy needs of the entire world. But if you add wind, hydro-power and further technologies to the mix, the picture looks even brighter and better, pricesely because this mix can well cater for the ups and downs of each of the different technologies. But once you say yes to nuclear power, the light goes out everywhere else. 

Different sources of energy compete for marketshare, but they are also complementary, in that the noncontinuous character of wind and solar power can be mitigated by including stored power in the mix of sources that are available, specifically hydrogen. Fossil fuel is underpriced right now, because the impact on the environment and the cost of policing supply aren't sufficiently included in the price. I remain convinced that nuclear power will be prohibitively expensive once risk factors are better taken into account (accidents, waste management, terrorism, etc). 

Dan: "For an average family with two vehicles that drive an average distance of 15,000 miles per year, an array of 32 kW would be needed - considerably more with larger vehicles. A 32 kW array would cost on the order of $160,000, and could not be installed just on the rooftop of a single home - it would likely require the south-facing rooftops of at least 4-8 houses to power.."

Perhaps that is the real cost, and the conclusion thus is that such a family should NOT be driving two inefficient vehicles over such large distances. If they cannot afford this, then why don't they move closer to work and shops, rather than to keep polluting the environment and forcing others to pay for that through government subsidies and protection. Note also that the land needed for concentrated thermal solar power is much less than for the solar panels one would typically put on top of buildings. Nevertheless, such panels could well power the cars of most people, since 70% of Americans drive less than 33 miles per day. They can refuel their car at work, using facilities at work that are powered by the solar panels on top of their office, and when they return home, they can plug their cars in at home, to top up enough for to drive back to work the next day.

Sure, there will always be people who will try to get others to pay for their harmful and costly lifestyle, but that's changing rapidly as information becomes increasingly available online and can be easily accessed by anyone who takes the effort to look for answers. Politicians have too long managed to stay in power by hiding simple facts from people. Many companies that have been bankrolling political campaigns over the years have vested interests in the status quo. Yet, issues such as global warming, 9/11 and the war in Iraq do make people think about environmental damage and terrorism and the cost of insurance and policing against attacks and accidents, and the way those costs are currently hidden and subsidized. I am convinced that, if the full facts are put on the table, fossil fuel and nuclear energy are both inefficient and harmful  compared to the range of clean and renewable alternatives that are widely available. So, put those facts on the table, Dan, and let's see how things look.

On batteries: The Tesla uses Lithium-ion (Li-ion) batteries, for a number of reasons. They charge rapidly, have higher voltage, weigh less and last longer than Nickel Cadmium (Ni-Cd) batteries. Li-ion batteries do not contain polluting substances such as cadmium, lead or mercury. Contrary to their name, they do not contain Litium either. They are classified by the federal government as non-hazardous waste and can be disposed of along with normal household waste. These batteries, however, do contain recyclable materials that make recycling a good idea. Tesla has made arrangements to have the car batteries safely recycled. The cost of recycling is built into the purchase price of the car. 

Another advantage of Li-ion batteries over Ni-Cd batteries is that Li-ion do not have the memory effect that makes that other batteries decrease in capacity when they are recharged before they are empty. Li-ion batteries do not have to be fully discharged, before they can be recharged, so one can top them up several times a day, e.g. at home or at the office. Nevertheless, Li-ion batteries will deteriorate over time, Tesla estimates that the battery pack needs to be replaced after about 100,000 miles. And that's precisely where hydrogen fuel cells can be more competitive.

Most Lithium-ion batteries will contain some Lithium and have a metal casing. There's much publicity around Lithium-ion polymer batteries. Traditional Lithium-ion batteries have metal casing, but the Lithium-ion polymer cells have a flexible, foil-type (polymer laminate) case and can therefore be smaller and thinner. Also, polymer electrolytes do not ignite as easily, so it makes sense to use polymer as separator between anode and cathode, while some Li-polymer batteries even use a polymer cathode (Moltech is developing a battery with a plastic conducting carbon-sulfur cathode). Lithium-ion polymer batteries can use Li or carbon-Li intercalation compound as anode. There are many developments in this area, with new materials beinmg tested all the time.

Here's a source that says: "The lithium ion battery does not employ any lithium metal. It is not governed by aircraft transportation rules relating to carrying lithium batteries in passenger airplanes." at:
I think what they refer to here is the metal casing that Lithium-ion polymer batteries don't have, so they are harder to spot using metal detectors. 

Here's a link to an electric bike that has a Lithium-ion polymer battery:

Note that this isn't about socialism. It's about what is most efficient. Currently, government taxes people who work and are successful, handing over much of that money to people who don't work and are unsuccessful, while much money also disappears in the waste that comes with bureaucracy, monopolies and cartels. 

What I propose to tax things that are harmful, such as greenhouse gas emissions. Were the proposed taxes on greenhouse gas emissions used to support the poor (with the idea that they needed help to pay the higher prices of fuel and meat), then this would simply make the poor continue with their current lifestyle, i.e. exactly the opposite of what I aim to achieve. The proceeds should go to better alternatives, in order to achieve the quickest change, e.g. in the light of the urgency to act on global warming. That will make such alternatives doubly more attractive by comparison, so even the rich (who could afford rising costs of fuel and meat) will take more notice and will consider making changes to their lifestyle as well. 

In conclusion, my proposal is neither left nor right, and it will work for both rich and poor. The hydrogen economy looks much more efficient than the current one.

Rather than competing technologies, I see batteries and fuel cells in many respects as complementary. Acceleration takes a lot of energy and batteries are well suited for that. They can also be topped up through regenerative breaking. But to drive longer distances, hydrogen is more economic, since it wouldn't be helpful to take more batteries on board given their weight.

Thus, I expect lithium-ion batteries and fuel cells to be used jointly in cars and I expect rapid improvement for both technologies in terms of weight, price and performance.

Here's some encouraging news in that respect:

Exxon Mobil Corp. has announced super-thin plastic sheeting to improve the power, safety and reliability of lithium-ion batteries in cars. Also, Exxon Mobil considers the film a breakthrough because it allows battery makers to build smaller and cheaper battery systems. 

Separator films are membranes that keep apart the battery's positive and negative fields, which are wrapped in a jelly-roll configuration. Such film squeezes multiple layers of plastic into a single white sheet the width of a human hair. The added layers enable the batteries to run at higher temperatures — and produce more power — while still protecting them from overheating. It also incorporates features that cause it to shut down if there is a short circuit in the battery.

PS: The article also gives an estimate for the cost of components. I take it this includes both electric motor and battery. It says that hybrids cost roughly $3,000 more than their gas-powered counterparts.

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