2021 Update: I posted this blog in 2014 and at the end wondered if Hydrogen is a green house gas. I figured to search the internet to see if there were any updates. I found one reference (actually first published in 2006) that indicates that Hydrogen has an indirect greenhouse effect that should be managed, but has a lower effect than the classics such as CO2 and methane.
The most fascinating aspect of the marine industry is the fact that it is nothing but a more technologically aggressive version of what takes place ashore. The world ashore changes and the world at sea changes just as fast. However, shore based technological concepts are all divided along the various technological stove pipes, while, at sea, technological aspects flow into the same pool of naval architects and marine engineers all day and somehow they have to deal with them and focus more tightly on efficiencies at the same time.
That means we get to be jacks of all trades (and, as some may argue; masters of none), but our much sharper drive to efficiency at sea often provides additional insights.
I just came across one of those issues in an article in Maritime Reporter. In the printed article (the printed article is better than the link I provided) Mr. Pospiech provides a very concise overview of Methane Slip.
Methane slip is methane that is not used as a fuel in an engine and basically escapes into the atmosphere.
It can be imagined that methane, as a gas, can hide in engine combustion space crevices and corners, not fully combust, and simply escape into the exhaust. That is a very significant issue with methane (LNG) as a fuel, since methane is a very powerful greenhouse gas (up to about two orders of magnitude as powerful as CO2). As a matter of fact it could be argued that shipboard LNG engines produce their own type of greenhouse gas problems and Mr. Pospiech addresses those issues. Mr. Pospiech describes how engine manufacturers deal with methane slip, and there are plenty of solutions ranging from catalysts to direct injection, and also provides some numbers that show that, in a well designed engine, the greenhouse effect of methane slip is very small indeed. He compares this against other human related atmospheric methane releases, such as cow emissions and pipe leakages (but does not mention fracking leakage) and makes a strong argument that shipboard engine methane slip is small (but not zero) with regard to overall methane greenhouse gas issues.
In his article he also makes the most important central point in marine engineering: In marine engines methane slip is minimized because we would rather use it as fuel to push our boat through the water than waste it by blowing it out of the stack.
I really appreciate Mr. Pospiech’s article, because it got me up to date with methane slip issues, and, as far as I can check, his data is correct (although incomplete). However, at the same time I am somewhat disappointed with his final paragraph, where he states:
“In general methane harms our environment, but compared to the enormous amount of direct methane emissions, the contribution to total world greenhouse emissions of marine engines is very minute.”
This paragraph actually sounds very defensive. Is it saying: “Yes, we produce greenhouse gasses too, but not as bad as those ashore”. Or is it saying: “Methane as a fuel is not a solution to greenhouse gas problems, but we are not to blame?”
Either way it avoids the central question: Is LNG a proper solution to greenhouse gas issues, or, even better, is it a viable step in our quest for sustainable energy?
That is an interesting question. Any engineer, who looked at corn ethanol from a simple efficiency point of view, could conclude from the outset that corn ethanol is a pointless scam. Unfortunately it has cost us all billions and has equally enriched those who willingly perpetrated the scam, and only now, about 20 years later, is the truth starting to surface. (I apologize for this rather unwieldy article link, but it provides lots of background info).
Unfortunately, the benefits and problems with LNG are going to take a lot more thinking and analysis to establish, and I would bet the answers will not be as simple as corn ethanol, but let’s make sure we have all the numbers and if no proper analysis of overall LNG effectiveness takes place ashore, maybe we, in maritime, may have to do it.
This leads me to the next question: Technologically, LNG is nothing but an interim step to a hydrogen economy. But is hydrogen a greenhouse gas? I did a quick Google on that one. The first link does not appear to have a solid ring of truth on that and it got worse from there. Looks like we have a lot of work to do there too, maybe someone ashore can take a look at that before we start to build fuel cell powered ships.