Classic bikes negligible emissions contribution overall

I was having a similar chat with my mower repair guy discussing Honda engines and their response to pollution laws. I wondered how many mowers you would have to get running to equal the greenhouse gas output of one ship burning bunker fuel.
 
Davo said:
I was having a similar chat with my mower repair guy discussing Honda engines and their response to pollution laws. I wondered how many mowers you would have to get running to equal the greenhouse gas output of one ship burning bunker fuel.
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About 24m3 a day isn't it? We learnt that modern ship engines are the most effective of all internal combustion engines, with very little energy lost.
 
Tippie said:
We learnt that modern ship engines are the most effective of all internal combustion engines, with very little energy lost.
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Shipping can be quite energy-efficient, but I'd guess that's not so much because ships have marvellously efficient engines.

No internal combustion engine is anywhere near 100% efficient. It's just not possible. I recall from thermodynamic studies that the efficiency of an ideal heat engine depends on the difference between the hot temperature at the beginning of the cycle and the cold temp at the end of the cycle. The maximum theoretical efficiency of any heat engine is (T1-T2)/T1 (temperatures in Kelvin).

For an IC engine, T1 is the combustion temperature at the beginning of the power stroke and T2 is gas temperature at the end of the power stroke. I don't know what those temperatures are, but if we guess 1500C and 800C as T1 and T2 respectively, the maximum possible efficiency comes out at 0.39, or 39%. Pretty crap eh? I dunno whether my guesstimated figures are anywhere near the mark, but you get the general idea. Remember that's the maximum possible efficiency. A lot of energy is lost to engine friction, imperfect combustion, etc.

Where does the rest of the fuel energy go? Most of it is lost as heat to the surroundings. It's sucked away by the engine cooling system. In a car, truck, train, motorcycle or aeroplane, that heat is pretty much all lost to the environment.

Ships are a different proposition because they're like floating cities that can carry the necessary plant for waste heat recovery systems. They have massive engines that produce vast amounts of waste heat. That heat can be put to use heating or cooling* the occupied spaces, desalination of seawater, cool storage for refrigerated cargo, producing steam for turbines to run electricity generators, and any other on-board processes that use heat. That's why ships are reasonably efficient forms of transport.

Engine efficiency aside, I reckon there's un-tapped well of energy for ships. All they need to do is to hoist a few sails. We did it that way for hundreds of years. Surely with modern sail technology we could do it a whole lot better now. I'd love to see a bulk fuel carrier glide past with a bunch of sails set.

* Waste heat can be used directly for cooling via absorption refrigeration. Absorption refrigeration has been around for donkey's years (gas-fired camping fridges for example), but it hasn't been used in ships very much. With environmental issues becoming more important in recent years, shipboard application of waste heat powered absorption refrigeration is a developing technology.
 
Tippie said:
About 24m3 a day isn't it? We learnt that modern ship engines are the most effective of all internal combustion engines, with very little energy lost.
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I think that is the key word there.

"The world's 90,000 vessels burn approx 370 million tons of fuel per year emitting 20 million tons of Sulphur Oxides. That equates to 260 times more Sulphur Oxides being emitted by ships than the worlds entire car fleet." quoted from https://livebunkers.com/bunker-fuel...,000 vessels burn,the worlds entire car fleet.
 
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And meanwhile, out in the real world:

"The fourth phase of the Shanghai Pudong International Airport expansion project formally began on Tuesday. After completion, the airport is forecast to be capabable of facilitating annual passenger throughput of 130 million passengers in 2030, and become a global benchmark for international aviation.

Also on Tuesday, Xiamen in East China's Fujian Province, launched its new airport construction project in Xiang'an. In total, eight projects started construction at the same time in Xiang'an, representing total investment of 62 billion yuan ($9.76 billion), covering aviation, infrastructure and socially-focused projects.

In terms of the airport, authorities in Fujian forecast the take off and landing of up to 380,000 flights per year, with an annual passenger throughput of 45 million, in addition to an annual cargo throughput of 750,000 tons.

Also on Tuesday, four key engineering projects including the No.1 freight forwarding depot within South China's Shenzhen airport intestified their work schedule, backed with a total investment of approximately 1.2 billion yuan."

Etc etc.

Read all about it - if you care - here. Just don't waste your time passing it on to any Greenies ..

www.globaltimes.cn

Airport projects in China set to take off - Global Times

www.globaltimes.cn

www.aerotime.aero

How China’s airport plans will make it the world’s largest passenger market‌‌‌ - AeroTime

The global pandemic may have brought air travel to a halt over the past 18 months, but China’s plans to construct airports remain undimmed. AeroTime takes a look at airport construction in China and how the proposals are set to help it take the title of world’s largest passenger market from the...
www.aerotime.aero www.aerotime.aero
 
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