The nice thing about DME compared to hydrogen is that it can use existing infrastructure, but it is important to note that DME can be made by any of the largely theoretical or piloted, renewable methods that are now discussed for hydrogen, specifically solar and wind, since DME can be made from hydrogenating carbon dioxide - either obtained from air or from waste streams from fossil fuel or biomass burning plants - or, even better, potentially the atmosphere. (The reason for using hydrogen to make DME rather than to use hydrogen directly as a fuel would be to exploit DME's superior physical properties and broader utility as discussed in other diary entries.) So if you're attached to some hydrogen hype with respect to possible sources of hydrogen (which is just a form of energy storage and not a form of primary energy), be aware that they can also be applied to make DME.
There is one possible source of DME that would make DME directly from renewably produced electricity. This is the Olah fuel cell, which reportedly has been made reversible, and was developed with the active participation of the Nobel Prize winning chemist George Olah. An Olah type fuel cell, which burns methanol, is already commercially available, albeit for small scale uses like laptops that can be recharged instantly by simply adding liquid methanol. (The recent ridiculous terrorism on aircraft scale probably had a negative impact on the marketing of this cool device.) However the marketed fuel cells are not like batteries: They only go in one direction. You can make electricity from methanol, but not methanol from electricity. If one could produce methanol from electricity directly from electricity, one could easily obtain DME from it. The driving force for doing so would be to avoid the huge drawbacks of methanol itself - it is poisonous, causing blindness, and very difficult to remove from water, with which it is completely miscible. Recent reports from Dr. Olah's labs - and he has made the methanol (DME) economy the center of his current work - indicate that he has made great strives at accomplishing this.
If this is true, George Olah has potentially provided humanity with one of the greatest tools it can possibly have in the fight against climate change. This should be garnering far more attention than it has. The man is a god-damned Nobel Laureate, for crying out loud!
My estimation is that the only form of renewable energy that is really scalable to the extent as to make a real immediate impact on the fossil fuels crisis is wind power. However, there are currently big drawbacks to wind, having to do with its unpredictable nature and the need to maintain spinning reserves to cover its performance. In fact, wind power can only be effective in the fight against climate change where storage capacity is available - and the only such storage capacity available on scale today is rivers and dams. When Denmark is dumping excess wind generated electricity on the Nordic energy grid in the middle of night, that electricity is used to power down dams, saving the water behind them for use during peak hours. It is only under these circumstances that wind makes a real impact.
Imagine though, that the reversible Olah fuel cell were available. Under these circumstances wind power could be stored easily. No vast tanks of gaseous hydrogen would be required. In fact, one could simply siphon off the liquid fuel and transport it, via pipeline, to run automobiles, or lawn mowers, or leaf blowers, or any of the devices for which you now use gasoline. In fact you could power these devices with fuel cells, replacing the loud gas motors with silent electric motors and increase the energy efficiency enormously in both thermodynamic and idling means.
Under these circumstances wind farms in North Dakota could do what the cannot really do now, provide energy in New York, or in Hawaii, or in South America at Tierra del Fuego.
Moreover, it happens that this cell could - conceivably is the big word here - do what nature does, take the energy of electrons and use it to store energy as a chemical fuel, while removing carbon dioxide from the air in an equilibrium driven process.
But the Olah fuel cell and my suggested modification involving atmospheric carbon dioxide - is still futuristic. Nowhere are commercial plants available to utilize this wonderful sounding technology. Indeed the reversible cell is not commercial, and important questions like the availability of ruthenium - a metal used in the system - are not available.
At this point I would like to refer to a very comprehensive and detailed discussion of one approach to obtaining DME as a by-product of the wood industry, a large player in Sweden's economy. This well referenced English language Swedish report, mostly focuses on DME and/or methanol from what is known as "black liquor," a side product of the paper pulp industry that is currently used as a low value heating fuel for the generation of electricity in Sweden and elsewhere. The report is over 300 pages long, but it does cover many of the broader issues related to DME and I will excerpt a few of them here rather than force people to go through the report.
The primary route to produce CO2-neutral motor fuels is through conversion of agricultural and forestry residues and organic wastes to gas (biogas), hydrocarbons (biodiesel, Fischer-Tropsch diesel), alcohols (methanol and ethanol), or dimethyl ether (DME). The hydrocarbons and the alcohols can be blended into petrol or diesel to facilitate market introduction and distribution. For example, 18% of the petrol in Sweden is today blended by 5% with ethanol (E5) without adjustments needed for the vehicles . The infrastructure could likewise accommodate methanol without much change.
In the long term, conversion to hydrogen is an attractive route, but this requires far greater changes to distribution systems and vehicles. Furthermore, as long as fuel cells will be much more expensive than current engines per kilowatt it is unlikely that the gain in energy efficiency or lower emissions will be enough as argument for replacement. The cost of a modern automobile engine is roughly $50/kW and for a suitable PEM fuel cell about 5000/kW. Thus, just the engine cost for a premium 160 hp automobile would be $590 000 instead of today's $5900. Hydrogen has physical properties that make it most unsuitable...
...Both methanol and DME show promising features as fuel candidates with the Otto and the diesel engine and comparing with other fuels from an LCA point of view, these fuels show highest energy efficiency from "well-to-wheel".
"LCA" is life cycle analysis, a short hand for "environmental cost."
The European pulp and paper industry is a vital part of an economic cluster - the paper and forest cluster - that generates an annual turnover of more than EUR 400 billion. In 2002, more than 1260 pulp and paper mills produced some 91 million tonnes of paper and board. The industry provides direct employment for about 250 000 people, and indirect employment - through the paper and forest cluster - for 3.5 million people. A pulp mill that produces bleached kraft pulp generates 1.7-1.8 tonnes of black liquor (measured as dry content) per tonne of pulp. Black liquor thus represents a potential energy source of 250-500 MW per mill...
...Today, black liquor is the most important source of energy from biomass in countries such as Sweden and Finland with a large pulp and paper industry. It is thus of great interest to convert the primary energy in the black liquor to an energy carrier of high value...
There are efficiency benefits:
The resulting biomass to methanol energy efficiency when only biomass is used as an external energy source was very high, 66% for methanol and 67% when DME was produced. The BLGMF plant generated additional electricity, solely consumed by internal plant units in that there was no need for additional energy...
There's a lot of economic analysis:
To estimate the potential revenue of methanol and DME a selling price of methanol and DME at the mill gate was calculated by assuming that the cost for the consumer should be the same as for petrol (methanol) and diesel (DME). The estimated price is about SEK 2095 (231) per tonne of methanol, when considering the current Swedish CO2 tax on petrol and similarly about SEK 3100 (341) per tonne of DME.
More on the diesel option:
DME as diesel fuel DME is a "natural" fuel for diesel engines due to the exceptionally high cetane number. Therefore, the same efficiency as for diesel fuel is possible for a diesel engine adapted for DME. DME is non-toxic and should have an inherent property of significantly reducing the toxic emissions in the exhaust in comparison to conventional diesel fuel. A significant reduction of the NOX emissions for DME in comparison to diesel fuel has been found in several studies. Particulate formation is largely avoided with DME in comparison to hydrocarbon fuels. DME also provide the opportunity for using higher rate of EGR, which further reduced the NOX emissions compared to diesel fuel. Deducing from the limited number of studies available, it seems that the use of a NOX reducing catalyst should be a viable solution for this fuel. Since DME is sulphur-free, the use of effective after treatment devices in general is more easily facilitated with DME than with sulphur containing fuels.
A particular problem with DME as a motor fuel is the fuel injection system...
Volvo's got a big commercial interest in this technology:
Volvo considers DME to be the major candidate as future energy carrier including fuel for heavy-duty transports. Since the early 90's Volvo has been studying energy sources and carriers issues with a holistic perspective. A holistic perspective regarding energy carriers is essential in the long-term energy scenario.
DME is a fuel, which is well suited for compression ignition engines (diesel process). The diesel engine has a comparatively high efficiency, which today can reach 45% at the best. There should be possibilities to increase the engine efficiency to approximately 50% in ten to fifteen years. Buses for urban transport may also be hybridized and this can further increase the efficiency by 20%, thus it might be possible to reach 60% in such applications. DME has a high cetane number and ignites more readily than most conventional diesel fuels. This implies possibilities for even more improvements in energy efficiency compared to today's diesel fuels.
Volvo has been active in developing a system for using DME is heavy-duty vehicles since 1996. In 1999 Volvo Bus presented the first DME-powered heavy-duty bus in the world, see Figure 8.2.
Technical descriptions and flow charts of industrial systems are also widely available in this report.
I will be back to discuss how DME can be integrated into a nuclear based economy, which potentially could make DME available for the displacement of all fossil fuels.