Saturday, 4 June 2016

Saving the planet with alcohol: An Ethanol Energy Economy

In this post, we'll detail how an ethanol economy might arise, its advantages and its effects on the environment and the world economy.


Today, fossil fuels represent 86% of the world's energy sources. Since the twentieth century, our use of coal, oil and natural gas has increased twenty-fold, and the trend continues. As billions in Asia and Africa gain access to energy-intensive technology, the demand for energy won't stop increasing any time soon.
Q-Max liquid gas tankers. They won't fit through Panama or Suez. 
The US Energy Information Administration projects that world energy consumption will increase by 56% by 2040. It is quite evident that the majority of this energy will be fossil fueled, as world CO2 production will rise to 45 billion metric tons. 
Pollution in Shanghai
Why is this important?

Well, it will cause global temperatures to rise. Arid regions become drier, sea levels rise, snow melts, species die and other such consequences are to be expected. In other words, we are smoking ourselves towards an ecological crisis, that is well underway. 

Things get significantly worse when our current sources of oil run out, and we start exploiting untapped reserves. These currently amount to more than twice the conventional reserves. As oil prices rise, it becomes more and more reasonable to start using these reserves.
Less than a third is conventional oil
Break-even prices.
Burning these as well could leave us in 2300 with up to 9 trillion tons of CO2, temperatures 9.5°C warmer and sea levels up to 6m higher. The latter would drown millions of people and render our historic coastlines unrecognizable. 
North American coastlines after sea levels rise 
What are we doing about it?

The current efforts to combat global warming can roughly be divided into two categories: efficiency and new sources.

Efficiency groups all efforts made to reduce the emissions from using fossil fuels. Eco-friendly transport, carbon-capture cooling towers in power plants, housing insulation, emissions regulations... they are currently the most convenient and most cost-effective in the short term.
A Golf 5 with a Bluemotion engine
New sources are all efforts made to reduce fossil fuel consumption by utilizing solar, nuclear, hydroelectric, wind, geothermal and novelty power. These range from mature applications, such as the Hoover dam, to laboratory tests, such undersea tidal turbines.
One of the Deltastream generators approved for use in Wales
These efforts are concentrated in well-developed countries. Countries like the United States and France generate a lot of their energy from nuclear power (19.5% and 75% respectively), while others such as Germany derive up to 30% of their power from renewable sources.

So what's the problem?

'Efficiency' efforts only slow down global warming. The biggest climate offenders are countries such as India and China, that are also the most resistant to ecological restrictions that would hamper their economic growth. For some states in Africa, economic growth would be impossible if restrictions similar to those of EU member states are applied. 

'New source' efforts are generally small-scale in application, compared to the prevalence of fossil fuel power. This is due to a trifecta of maluses that hinder their widespread use: low energy density, discontinuous supply and difficulty of storage.

Energy sources like solar power do not generate much electricity per square meter. This is a problem also encountered with wind and sea-derived energy sources. 
Gujurat Solar Park. A coal-fired plant definitely takes less space.
Discontinuous supply means that the energy source does not generate the same amount of watts over a long period of time. For solar power, energy is not generated at all at night. For wind, calm days means no power. For sea, the tides are widely spaced apart. Other sources, such as nuclear, can provide continuous supply, but are nearly impossible to ramp up and down in response to changes in the population's energy use habits. 

Finally, electricity is much easier to transport than it is to store. For example, a solar power plant would optimally have the ability to store half of the power generated during the day, to release it during the night. Realistically, it would require kilotons of expensive batteries or that would render storage prohibitively expensive (and would defeat the ecological purpose entirely). Other options, such as molten salts or hot water, are inefficient and low-capacity, leading to expensive and lossy solutions. This is especially important, as storing the excess energy to compensate for lulls in production would make wind and solar energy competitive compared to more secure sources.
A solar thermal power plant using molten salts to stare and transfer solar energy.
The other option to storing the electricity is at the user's end: electric vehicles, for example, have very large batteries designed to store all the energy required for the trip. 

If neither solution to storing the energy generated is possible, then something awkward and expensive such as recharge points every 100km would be necessary.

So, Ethanol.

Ethanol, formula C2H6O, is already commonly used as a fuel.
Ethanol pump
Replacing fossil fuels with ethanol generated through a modified Sabatier reaction can solve most of the aforementioned issues with a transition from fossil fuels to renewables and other more ecological options.

The process involves these steps:

-Electrical power is generated by a power station
-Electricity is used to break down water into oxygen and hydrogen
-Atmospheric CO2 is added to hydrogen in a 300-400°C reactor
-The Methane produced is converted into Ethanol
-Liquid Ethanol is sold just like gasoline today

The first advantage comes from the properties of Ethanol itself. It is an easy-to-handle, non-toxic fuel that contains 25MJ/kg, an energy density more than thirty-five times better than the best lithium batteries.

Energy density chart
The second advantage is that Ethanol can be the basis of many of the familiar hydrocarbon products we currently derive from petroleum. It can be converted to Gasoline so that it may be employed directly in all modern transport with zero set-up costs. It may be converted to a hydrophobic hydrocarbon, so that it may be transported through existing pipelines without worrying about ethanol's tendency to absorb water. It can even be converted into ethylene for use as a precursor to plastics. 

Other advantages come from the centralization of power production, with associated savings in large-scale power plants instead of multiple smaller ones, and the ability to apply technological upgrades all at once, to a small number of units, rather than trying to convince multiple power companies to do the same.
A carbon capture and storage (CSS) plant in Germany.
Ecologically, the carbon-capture process for producing ethanol is the perfect solution to the global warming crisis. It tackles the problem at the source by removing CO2 from the air, rather than trying to mitigate the effects. While the production of ethanol is at best carbon-neutral, the overall implementation would be carbon-negative. CO2 would have to be captured from the air in the initial production run. When it is burned, that carbon returns to the air... but any reserves not burnt yet retain CO2 indefinitely. It would remain carbon-negative as long as the industry expands, as any new power plant being produced captures an initial reserve of CO2. 

It would also undercut the biofuels industry and their less-than-carbon-neutral products. The latter competes with agricultural land for food, and is most likely to be grown by impoverished farmers as a cash crop, thereby destroying their long-term potential earnings through soil erosion and dehydration and other headaches.
Remember how this matter was solved in the last century
In raw efficiency terms, the carbon capture for energy storage method could potentially be less wasteful than producing electricity directly. This is due to the fact that if the initial power source is thermal, then the 300-400°C Sabatier reactor could be used as a waste heat capture system for no extra cost. It is uncertain, but hydrogen produced from electrolysis could also be used as a gaseous reactant immediately, instead of passing through an energy-intensive liquefaction process. Liquid Oxygen can be sold as rocket fuel.

By producing an easily stored and transportable fuel, electrical energy can be traded across international distances. This is of major importance to developing countries, which as mentioned earlier, are the greatest emissions producers to come. A solar farm in Morocco can trade its power production to neighboring European countries. Nuclear power plants on mainland USA can send their power to Alaska to wean it off fossil fuels. Countries like China and India would have an incentive to halt investments in coal production from harder and harder to extract sources. International trade of long-term storables is another solution to the fluctuation in energy production by renewables, as it allows investors to sell excesses and import against deficits.
Could be transporting carbon-capture ethanol instead.
Finally, as ethanol can be produced from traditional fossil fuels, states unable to pay for the carbon capture and conversion equipment or not equipped with renewable sources of electricity may still participate in the ethanol economy. 

Alternatives and issues

The first major alternative to the ethanol economy is the methanol economy. Methanol is just as easily produced as ethanol, and it is mostly immune to hydration and water-retention problems.

Furthermore, it burns more easily than ethanol and is more competitive in terms of carbon efficiency. During the transition period between a fossil fuel and a carbon-negative economy, it has the advantage because it can be blended easily with gasoline and does not encourage competition with food crops for production of biofuels.
Timo Habermann, Top Methanol Dragster
However, just as ethanol, it cannot be sent directly through existing pipelines without requiring conversion into a hydrophobic hydrocarbon first. It is extremely toxic, which would make its widespread use problematic (although it is not much more of a health risk than gasoline). It also has a lower energy density and is corrosive to current internal combustion engines. The latter would make the switch from gasoline to methanol an extremely costly measure, especially in the private sector. It also burns invisibly.
Invisible methanol fire at a race pit stop
Another commonly proposed carbon-neutral economy is hydrogen

Hydrogen production is necessarily more efficient than any hydrocarbon-based carbon-capture method, as it uses the hydrogen from electrolysis directly as a fuel. It also offers photoelectrochemical water splitting, the cleanest energy production method. It also encourages the trend of zero-emissions cars using hydrogen fuel cells and electric motors. It also also non-toxic.
A hydrogen fuel cell
Despite these advantages, hydrogen is a poor choice. It requires a huge investment in terms of transportation, storage and safety measures. The latter is especially important, as hydrogen is explosive and burns with an invisible flame. Hydrogen has an extremely low energy density, so it has to be compressed to viable. This means, even more so than simply requiring a hermetic container like methanol, it would need an insulated and pressurized tank, with corresponding costs to the private sector.

A hydrogen economy would not allows a smooth transition away from fossil fuels either, and while it would not encourage biofuel cash crops, it would force developing countries dependent on fossil fuels to run on completely separate equipment. This does not promote investment or encourage development of either system if they are forced to completely replace the other.

The Future

An ethanol economy is even more interesting in a science-fiction setting. 

In the near future, an ethanol economy would be produced in literal 'energy sectors' that would concentrate power production infrastructure. For the regular person, not much would change. Cars would look pretty much the same, with internal combustion engines running on liquid fuel. In fact, engines might return to the displacements of earlier decades, as CO2 being captured 'upstream' would remove emissions restrictions on users 'downstream'. 
Runs on Ethanol?
Developing countries would finally be incentivized to exploit natural resources other than oil and gas. Countries like Morocco would continue to expand on their solar power industry. Saudia Arabia would remain in the energy sector by plugging up empty oil wells and developing its nuclear energy. China might build up a 'strategic reserve' of ethanol, made from domestic coal, to protect itself from market fluctuations. 

Moving forward, low energy density renewables could be replaced by developments in nuclear energy. If sustainable fusion becomes feasible, it would benefit from power production centralization and fit right into the ethanol economy. A de-regulation of fission fuels might lead to the development of breeder reactors, able to recycle nuclear waste and cut uranium prices to a few percent of what it is today. 
Experimental Breeder Reactor II
It is harder to predict the far future. Enough CO2 might have been removed from the atmosphere as ethanol reserves to justify hydrogen extraction techniques to be used (CO2 to Ethanol to Hydrogen+Carbon). Hydrogen handling technology might eventually make direct use of it economical. Alternatively, pure electric infrastructure might take place, with electricity generated by a power planet consumed directly from the grid. If nuclear power generation is easily expandable, then it might outstrip immediate demand. This would justify the use of lower efficiency but longer-term storage of hydrogen - we might see the return to a full complex hydrocarbon economy!

In a post-apocalyptic setting, it might be interesting to have vehicles powered by alcohol from rudimentary fermentation and distillation, long after the advanced carbon-capture machinery has broken down.

However, an ethanol economy can be broken by non-terrestrial input of hydrocarbons. These can be found on Titan... if someone invests the time and money into importing fuel from another planet, then it is possible that the Earth-produced ethanol would become the pricier product. Interesting plot material indeed...
Titan's Kraken Mare, explored by an interplanetary BP prospector scientific probe
Conclusion

An ethanol economy directly solves the problem of CO2 emissions. Unlike all-or-nothing alternatives, its implementation can be gradual, and it neither requires huge infrastructure investments, research to be done or asks much from the consumer. Poorer states can transition into the ethanol economy without invalidating their previous energy investments, and countries who have unused fossil fuel reserves by the time this is implemented can still leverage their wealth. 

It wins out over methanol, hydrogen and pure electric options, at least for modern considerations. Best of all, it does not force difficult choices, such as whether to grow a food or cash crop, as is the case with biofuels. 

4 comments:

  1. For something like this it would probably be better to take the CO2 from seawater.
    https://bravenewclimate.com/2013/01/16/zero-emission-synfuel-from-seawater/

    In some ways dimethyl ether might be a better synthetic fuel
    https://www.aboutdme.org/index.asp?sid=48
    http://www.dailykos.com/story/2006/10/7/254867/-

    Jim Baerg

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    Replies
    1. Science marches on! Thanks for the links.

      Dimethyl ether is gaseous at standard temperature and pressure. It boils at -24 degrees Celsius, which might not be practical in the short term. That is a crucial step towards convincing large power companies to use ethanol instead of impractical hydrogen, inefficient electrical or nothing at all.

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  2. Yes DME is a gas at STP, but like propane it becomes a liquid at several atmospheres pressure, in fact at a bit less pressure than propane.

    So DME can be stored in the same sort of tank as propane, and used to run vehicles in much the same way that propane is now. The main difference is that DME is best used in diesel engines, resulting in higher efficiency. DME burns much cleaner than ordinary diesel fuel.

    Jim Baerg

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    Replies
    1. DME could be a second-generation fuel. Diesel engines are more efficient, and cleaner burning would mean less pollutants that we cannot compensate for through carbon capture.

      However, I must stress again how important it will be to provide an option that requires very little modification to existing cars for the transition between fossil and carbon-capture fuels.

      DME would require installing a pressure tank and abiding to more stringent safety regulations. It might end up representing as much as LPG, which is 3% of all cars.

      I think providing an alternative, such as 85% ethanol, 15% gasoline (E85), where ethanol is produced by carbon-capture plants, is much more important than a possibly more efficient alternative. The alternative would require customers to buy a new car!

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