Hydrogen economy?

Here's a little more discussion of the prospects for a "hydrogen economy". I'd welcome it if it were practical, but I'm still skeptical. (Some previous discussion of hydrogen here).

Hydrogen economy sustainable in 15 years (7/17/08)

Hydrogen would be most efficient when used in fuel cells, which extract energy via a chemical reaction rather than by combustion. But fuel cells are still very expensive and distributing hydrogen to consumers would require new infrastructure. Consequently, a large-scale transition to hydrogen will require help from the federal government.

More on this report: Hydrogen Vehicles Coming Soon? Two Million Could Be On Roads By 2020 (7/17/08), Fuel cell cars still 15 years away at best: study (7/17/08)

Looking at Hydrogen to Replace Gasoline in Our Cars (7/3/08)

The jury is still out on whether hydrogen will ultimately be our environmental savior, replacing the fossil fuels responsible for global warming and various nagging forms of pollution. Two main hurdles stand in the way of mass production and widespread consumer adoption of hydrogen “fuel cell” vehicles: the still high cost of producing fuel cells, and the lack of a hydrogen refueling network.

Reining in manufacturing costs of fuel cell vehicles is the first major issue the automakers are addressing. While several have fuel cell prototype vehicles on the road—Toyota and Honda are even leasing them to the public in Japan and California—they are spending upwards of $1 million to produce each one due to the advanced technology involved and low production runs. ...

Another problem is the lack of hydrogen refueling stations. Major oil companies have been loathe to set up hydrogen tanks at existing gas stations for many reasons ranging from safety to cost to lack of demand. But obviously the oil companies are also trying to keep customers interested in their highly profitable bread-and-butter, gasoline.

More problems with alternative energy

It's certainly not encouraging to find research that casts doubt on the economic or technological viability of energy sources other than fossil fuels. There are two compelling reasons the whole world needs to transition away from fossil fuels: (1) To derive energy from fossil fuels requires combustion, which releases large amounts of the greenhouse gas CO₂, and other pollutants, into the atmosphere. (2) Resources of the most convenient (for use in land vehicles and aircraft) fossil fuel – petroleum – are rapidly dwindling, especially in easily accessible locations, so the price will necessarily increase over time, as will the risk of armed conflict between countries to protect access.

On the other hand, it's necessary to be as realistic as possible about the alternatives, in order to avoid heading down a path that could be (quite expensively) wrong.

So in a couple of recent posts here and here I discussed various studies that raised cautions about the potential for solar energy, nuclear energy, hydrogen (for fuel cells), and biofuels. New cautionary reports about these various alternatives keep appearing.

Let's begin with solar. There's more than one way to take advantage of energy from the Sun. Photovoltaic production of electricity directly from sunlight receives the most attention. But there are other approaches, such as solar thermal energy and perhaps (some day) even the use of artificial photosynthesis:

Artificial Photosynthesis Moves A Step Closer (4/28/08)

Imagine a technology that would not only provide a green and renewable source of electrical energy, but could also help scrub the atmosphere of excessive carbon dioxide resulting from the burning of fossil fuels. That’s the promise of artificial versions of photosynthesis, the process by which green plants have been converting solar energy into electrochemical energy for millions of years. To get there, however, scientists need a far better understanding of how Nature does it, starting with the harvesting of sunlight and the transporting of this energy to electrochemical reaction centers.

But most commonly when "solar energy" is discussed, photovoltaic technology is what's actually meant. The technology has existed for many years. The problem has always been cost. Even today it's estimated to be almost ten times as expensive per kilowatt-hour to generate electricity with photovoltaics as it is from fossil fuel:

Expert Foresees 10 More Years Of Research & Development To Make Solar Energy Competitive (4/7/08)

The single biggest challenge, Gray said, is reducing costs so that a large-scale shift away from coal, natural gas and other non-renewable sources of electricity makes economic sense. Gray estimated the average cost of photovoltaic energy at 35 to 50 cents per kilowatt-hour. By comparison, other sources are considerably less expensive, with coal and natural gas hovering around 5-6 cents per kilowatt-hour.

Because of its other advantages -- being clean and renewable, for instance -- solar energy need not match the cost of conventional energy sources, Gray indicated. The breakthrough for solar energy probably will come when scientists reduce the costs of photovoltaic energy to about 10 cents per kilowatt-hour, he added. "Once it reaches that level, large numbers of consumers will start to buy in, driving the per-kilowatt price down even further. I believe we are at least ten years away from photovoltaics being competitive with more traditional forms of energy."

Major challenges include developing cheap solar cells that work without deterioration and reducing the amounts of toxic materials used in the manufacture of these cells. But producing low cost photovoltaics is only a step in the right direction. Chemists also need to focus on the generation of clean fuels at costs that can compete with oil and coal.

Nuclear power continues to be quite problematical too. Many of its problems have been known for a long time, such as the difficulty of safely disposing of spent fuel and the dangers of diversion of nuclear fuel to weapons. But more recently attention has begun to focus on the increasing cost of extracting and processing uranium, and the greenhouse gases generated in that process:

Questioning Nuclear Power's Ability To Forestall Global Warming (4/30/08)

Rising energy and environmental costs may prevent nuclear power from being a sustainable alternative energy source in the fight against global warming, according to a new study.

In the article, Gavin M. Mudd and Mark Diesendorf investigate the "eco-efficiency" of mining and milling uranium for use as fuel in nuclear power plants. ...

The study points out that supplies of high-grade uranium ore are declining, which may boost nuclear fuel's environmental and economic costs, including increases in energy use, water consumption and greenhouse gas emissions. In addition, newly discovered uranium deposits may be more difficult to extract in the future -- a further drain on economic and environmental resources.

Here are two somewhat longer articles about this report, with some rebuttal from the uranium mining industry: Nuclear may lose green tag if fuel costs rise and Nuclear energy becoming less sustainable.

Finally, it's often overlooked that there's one additional increasingly scarce resource that's usually needed to produce energy by many different technologies: fresh water.

Water Needed To Produce Various Types Of Energy (4/17/08)

It is easy to overlook that most of the energy we consume daily, such as electricity or natural gas, is produced with the help of a dwindling resource – fresh water. Virginia Tech professor Tamim Younos and undergraduate student Rachelle Hill are researching the water-efficiency of some of the most common energy sources and power generating methods.

When the requirements for fresh water are considered, new disadvantages appear for many alternative energy sources, especially biofuels and nuclear energy:

According to the study, the most water-efficient energy sources are natural gas and synthetic fuels produced by coal gasification. The least water-efficient energy sources are fuel ethanol and biodiesel.

In terms of power generation, Younos and Hill have found that geothermal and hydroelectric energy types use the least amount of water, while nuclear plants use the most.

Update, 5/14/08:

More headaches of nuclear energy. There's a new, longish Scientific American article on the problem of nuclear fuel recycling: Nuclear Fuel Recycling: More Trouble Than It's Worth


Tags: nuclear power, solar power, photovoltaic power, ethanol, biofuel

More about alternative energy

About a month ago, I wrote about the shortcomings of various alternative energy sources. That was mainly about a variety of problems with nuclear energy, solar energy (photovoltaics), and hydrogen.

I didn't even get into the subject of biofuels, but I should have, because the problems in that area are becoming painfully obvious.

Ordinarily I would not expect to find much significant reporting on a scientific/technical subject in Time magazine, especially something that challenges "conventional wisdom". But via DarkSyde at Kos I see there's an interesting article on the problems of "biofuel": The Clean Energy Scam

Several new studies show the biofuel boom is doing exactly the opposite of what its proponents intended: it's dramatically accelerating global warming, imperiling the planet in the name of saving it. Corn ethanol, always environmentally suspect, turns out to be environmentally disastrous. Even cellulosic ethanol made from switchgrass, which has been promoted by eco-activists and eco-investors as well as by President Bush as the fuel of the future, looks less green than oil-derived gasoline.

Meanwhile, by diverting grain and oilseed crops from dinner plates to fuel tanks, biofuels are jacking up world food prices and endangering the hungry.

The Time article focuses on the loss of rainforest, and consequently the loss of its ability to soak up and sequester CO₂. When the forest is gone, CO₂ will still be incorporated in biomass (crops of some sort). But then that is converted to biofuel, and released back into the atmosphere when it's burned. (To say nothing of the energy that's just wasted along with release of CO₂ when the forest biomass is burned to clear it away.) Given all the energy that has to be expended to grow and harvest biofuel crops, with resulting additional release of CO₂, we are worse off in terms of greenhouse gas emissions than if we just burned oil (or even coal).

But that's not the only serious problem. Crops that are grown to make fuel (from sugar cane, corn, switchgrass, or whatever) use land where food crops (for people and animals) could be grown instead. Driving up the cost of food for everyone on the planet. (Have you checked the price of bread or eggs at the market recently?)

Economists have spoken out about this problem for several years, when the hype for biofuels and ethanol was just beginning to build. For instance, we have from Howard Simons in early 2006: Making Our Food Fuel Isn't the Answer

If high prices strengthen energy's claim on food supplies, governments everywhere will intervene on behalf of their hungry citizens. If low prices torpedo biofuels' economics, governments everywhere will respond with subsidies for these industries. Only an elimination of current mandates and subsidies today will avoid these problems tomorrow, but the likelihood of this happening is near zero. Somehow I believe we will rue the day when we decided to make food and fuel substitutes at the margin.

In early 2007 Paul Krugman picked up the story: The Sum of All Ears

There is a place for ethanol in the world’s energy future — but that place is in the tropics. Brazil has managed to replace a lot of its gasoline consumption with ethanol. But Brazil’s ethanol comes from sugar cane.

In the United States, ethanol comes overwhelmingly from corn, a much less suitable raw material. In fact, corn is such a poor source of ethanol that researchers at the University of Minnesota estimate that converting the entire U.S. corn crop — the sum of all our ears — into ethanol would replace only 12 percent of our gasoline consumption.

So ethanol doesn't even help the U. S. all that much in terms of dependence on foreign oil. And this February Krugman returned to the subject here, linking to this: Ethanol Demand in U.S. Adds to Food, Fertilizer Costs

About 33 percent of U.S. corn will be used for fuel during the next decade, up from 11 percent in 2002, the Agriculture Department estimates. Corn rose 20 percent to a record on the Chicago Board of Trade since Dec. 19, the day President George W. Bush signed a law requiring a fivefold jump in renewable fuels by 2022.

Increased demand for the grain helped boost food prices by 4.9 percent last year, the most since 1990, and will reduce global inventories of corn to the lowest in 24 years, government data show. While advocates say ethanol is cleaner than gasoline, a Princeton University study this month said it causes more environmental harm than fossil fuels.

And then last week Krugman had even more: Grains Gone Wild

The subsidized conversion of crops into fuel was supposed to promote energy independence and help limit global warming. But this promise was, as Time magazine bluntly put it, a “scam.”

This is especially true of corn ethanol: even on optimistic estimates, producing a gallon of ethanol from corn uses most of the energy the gallon contains. But it turns out that even seemingly “good” biofuel policies, like Brazil’s use of ethanol from sugar cane, accelerate the pace of climate change by promoting deforestation.

And meanwhile, land used to grow biofuel feedstock is land not available to grow food, so subsidies to biofuels are a major factor in the food crisis. You might put it this way: people are starving in Africa so that American politicians can court votes in farm states.

Here's a report of a scientific study on the issue: Some Biofuels Risk Biodiversity And Could End Up Harming Environment

Corn-based ethanol is currently the most widely used biofuel in the United States, but it is also the most environmentally damaging among crop-based energy sources.

Finally, to bring this back to a solid scientific foundation, Sean at Cosmic Variance reminds us that Energy Doesn’t Grow on Trees

In particular, biofuels (such as ethanol) and hydrogen are not actually sources of energy — given the vagaries of thermodynamics, it costs more energy to create them than we can get by actually using them, as there will inevitably be some waste heat and entropy produced

.

Although all this bad news about just about every prospective near-term form of alternative energy is discouraging, there are a few other options that may become available in the slightly more distant future. There's the old perennial, controlled nuclear fusion. Even though work on that is even more active than ever, it's still at least several decades away.

But there's another significant option that's often overlooked: solar power satellites. This technology uses very large arrays of photovoltaic panels high in orbit around the earth. The energy is beamed back to the ground in the form of microwaves. (So this should not be confused with simply using mirrors to redirect additional sunlight, which presents serious problems of its own.)

Solar power satellites also have many uncertainties and potential problems, but the largest is simply boosting enough of them into orbit, and maintaining them. A possible approach to those problems involves space elevators. But those, again, present a whole additional set of challenges.

For now, here are a couple of articles from last fall with more details:

Pentagon backs plan to beam solar power from space

New Space Solar Power Report from DoD NSSO

Tags: ethanol, biofuel, alternative energy, solar power satellite

Alternative energy sources

The outlook on energy alternatives to fossil fuels is looking a little bleak.

There have been several recent studies or reports casting significant doubt on the economic and/or environmental viability, at least for the near and intermediate future, of some of the leading contenders to supplant fossil fuels.

First up: nuclear power. Of course, environmentalists and others have had grave doubts about nuclear for decades, because of problems with safe disposal of spent nuclear fuel and the dangers of diversion of enriched uranium to manufacture of weapons. On top of that, there is the argument that replacing generation of power from burning fossil fuels with generation from nuclear sources may well contribute more to release of CO₂ into the atmosphere than continuing to use fossil fuels. This comes about because so much power (generated from burning of fossil fuels) will need to be expended simply to build from scratch many new nuclear power plants and sharply increase the mining and purification of uranium:

Nuclear Power Not Efficient Enough To Replace Fossil Fuels, Study Finds

Nuclear energy production must increase by more than 10 percent each year from 2010 to 2050 to meet all future energy demands and replace fossil fuels, but this is an unsustainable prospect. According to a report published in Inderscience's International Journal of Nuclear Governance, Economy and Ecology such a large growth rate will require a major improvement in nuclear power efficiency otherwise each new power plant will simply cannibalize the energy produced by earlier nuclear power plants.

Here's another way to look at this. If you consider just the marginal costs of producing a kW of energy from nuclear fuel vs. fossil fuel – counting (if you can) both direct economic costs and costs due to release of CO₂ into the atmosphere – nuclear energy might be superior. However, if you also consider the capital expense (both direct and indirect) required to build enough new nuclear facilities to replace existing conventional facilities and also meet increased demand, then (according to the study) nuclear loses.

So what about using other energy sources as alternatives to fossil fuels, in order to significantly reduce dependency on fossil fuels and release of CO₂? Like hydrogen, for example. Of course, this depends on further developing a lot of technology that's either not cost-competitive yet (fuel cells) or not even available yet (practical and safe means of storing and transporting hydrogen). To say nothing of the capital costs (as above) needed to build hydrogen infrastructure if and when the technology is available.

Even if technology can solve the difficult problems of storing and transporting hydrogen, there's another fundamental problem. Hydrogen itself is more of a form of energy suitable for transport and storage than it is a readily available source of energy (like sunlight or fossil fuels) that can be acquired or extracted (relatively) cheaply. There's no hydrogen just sitting around (like natural gas) waiting to be mined and distributed. Energy has to be consumed in order to separate hydrogen from oxygen, which together make up H₂O. This energy has to come from some other source, as input to the electrical/chemical process that separates out hydrogen (or recombines it to make another fuel such as methane). This energy is regained later – but always with some percentage loss – when hydrogen is chemically recombined with oxygen (as in a fuel cell).

There really isn't any energy advantage to hydrogen at all, except for the (presumed) advantage over batteries in storage and transport. Of course, energy in a storable form is required for use in vehicles like cars and airplanes, in spite of the unavoidable losses along the way. The following essay goes into all of this in more detail.

The Hydrogen Economy

Skeptics scoff at perpetual motion, free energy, and cold fusion, but what about energy from hydrogen? Before we invest trillions of dollars in a hydrogen economy, we should examine the science and pseudoscience behind the hydrogen hype.

There are some problems with the essay. First, one does not "make" hydrogen. It is extracted from chemical compounds like water, hydrocarbons (fossil fuels except coal), or biomass (carbohydrates, cellulose, etc.). Energy has to be input to the process in order to break the chemical bonds between hydrogen and other elements (carbon or oxygen). You get the energy back out when hydrogen recombines with oxygen or carbon (in a fuel cell, combustion chamber, etc.) – but always at some loss.

Second, the essay mostly assumes hydrogen will be stored and transported in liquid form, which is difficult and expensive, since liquid hydrogen boils at an ultracold -253°C. There is some hope that technology can be developed to store gaseous hydrogen in exotic solid materials at reasonable temperatures and pressures. (Recent examples: here, here.) However, at this point that's still conjectural. The larger point is that a practical "hydrogen economy" is still, at best, not in the near future.

So hydrogen is not an energy source, and it is even very problematical as a way to store energy in a portable form for use in cars and airplanes. Fortunately, there are other ways to make energy portable, such as batteries. A Toyota Prius uses nickel metal hydride batteries to store energy from the regenerative braking system, and it seems to be an economically successful product. Lithium ion batteries, such as are used in laptop computers, have a higher energy density than the nickel metal hydride type. They have problems of their own, but significant improvements are being made. (See here, here, here.)

That still leaves the problem of developing additional actual sources of energy, that are alternatives to fossil fuels. Ethanol (grain alcohol) is getting a lot of publicity these days. It's politically popular with the agricultural industry, for obvious reasons. Ethanol partially solves one problem with fossil hydrocarbon fuels – by removing some dependence on politically unstable areas as a fuel source. But ethanol does nothing for the problem of CO₂ emissions.

And it creates serious problems of its own, such as driving up the cost of agricultural products needed to feed people. Further, as with hydrogen, it takes a lot of energy to extract ethanol (or other energy carriers such as other biofuels or methane) from agricultural crops or biomass. Critiques of ethanol and other biofuels are not new, though they don't seem to get the attention they deserve. (See here, here, here, for example.)

Other alternatives? There's always solar (photovoltaic) energy. Of all new but currently available alternative energy sources to fossil fuels (whether oil, natural gas, or coal), solar seems to be the most economical, especially taking reduced CO₂ emissions into account.

But of course, solar also has its problems too. These include capital costs for building infrastructure to capture solar energy and to store it (for peak or nighttime use) or transmit it from the sunniest areas with low land prices. It's these capital costs (initial construction and eventual replacement) that hurt, since the marginal cost of each kWh is almost nil.

However, making detailed economic comparisons with traditional energy sources is rather difficult, as this study argues: Cloudy Outlook For Solar Panels: Costs Substantially Eclipse Benefits.

It would seem that the real difficulty of economic analysis lies in predicting the future costs of conventional energy sources – fossil fuels, especially oil. Some of the problems:

• How to estimate costs associated with CO₂ emissions, given that the idea of global warming itself is so controversial (especially in the minds of economists and political officials, if not atmospheric scientists). To say nothing of estimating social costs of conjectural side effects, such as sea level rise, serious water shortages, detrimental impact on human and animal health, impact on agricultural production, etc.
  
• How to estimate the foreseeable rise in price of fossil fuels (especially oil) due to political instability, rising extraction costs (deep ocean sources), depletion of supplies, and rapid increase in demand from developing parts of the world. (There are large uncertainties in all of these factors, and some cost has to be allocated to this uncertainty itself.)
  
• How to handle the issue of proper pricing for energy at times of peak demand, as opposed to off-hours. (The report just mentioned discusses this.)
  

At present, the cost of solar energy, taking into account such things as installation costs, depreciation, etc., might well be two to four times the cost of energy from fossil fuels. But at least the cost of solar is pretty certain to decline, while the cost of energy from fossil fuels can only increase – and at a worrisomely unpredictable rate, in view of the uncertainties just listed.

Tags: nuclear power, solar power, photovoltaic power, hydrogen economy, ethanol, biofuel