Wikipedia:Reference desk/Archives/Science/2018 October 15

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October 15

Diesel-electric rail emissions

Someone in the UK House of Commons recently asked if switching freight from road to rail was a priority for the government in its bid to reduce carbon emissions, and the Prime Minister said she thought that would be a good idea. However having looked into it, it seems the majority of freight trains in operation in the UK are Diesel-electric British Rail Class 66's. Would this specific train model offer up any improvements over say road haulage, on a quantitative basis? The British Rail Class 66 article just states:

Numbers 66 752-779 were the last Class 66s ordered for service in Great Britain because of increasingly stringent emission regulations. 66 779 was the last Class 66 to be ever built. Although the Class 66s meet stage 3a of the regulations, they do not meet stage 3b. Stage 3b would have required additional exhaust treatment equipment that could not easily be accommodated within the UK loading gauge. The same restrictions apply to the Class 68 and Class 70. The restriction does not apply to second-hand locomotives, provided that they are imported from within the European Union. The purpose of the regulation was to put a cap on the total number of non-compliant locomotives in the EU.

Many thanks. Uhooep (talk) 01:16, 15 October 2018 (UTC)

This looks like it may be relevant or at least links to useful sources, especially on page 44-45 [1] Nil Einne (talk) 03:11, 15 October 2018 (UTC)

The key source cited there seems to be [2] and if you just care about their estimate, I think page 65 of the report (or 68 of the PDF) may be the key one. Nil Einne (talk) 03:26, 15 October 2018 (UTC)

I didn't do an exhaustive search on this subject, but the "additional exhaust treatment equipment" is probably to reduce soot and/or NOx emissions. Soot is of course mostly carbon, but the carbon emissions the government is talking about are carbon dioxide emissions. So those are unrelated. As far as carbon dioxide emissions are concerned, every somewhat modern diesel locomotive outperforms lorries by a large margin.

Switching from road to rail will require additional locomotives. Some second-hand Class 66s will be available from the continent (I see them there a lot less than a few years back, as they got replaced by electrics), but this switch will require new locomotives too. And I understood that the UK is rapidly electrifying its rail network. PiusImpavidus (talk) 10:21, 15 October 2018 (UTC)

Railways are generally assumed to be up to 5 times more energy effective in a similar logistic task compared to road transportation. This is mainly because of the Rolling resistance, which is very low with steel wheels on a steel railway, and the common very low Grade (slope) of railtracks compared to the much higher grades common in road construction. --Kharon (talk) 18:49, 15 October 2018 (UTC)

Energy_efficiency_in_transport#Trains has some relevant information.--Wikimedes (talk) 04:46, 16 October 2018 (UTC)

No, the UK is not "rapidly electrifying its rail network".  I can't cite specific articles, but this subject comes up regularly in Modern Railways magazine, which I read.  While there have been electrification projects established in recent years, they have tended to overrun their budgets and have been subject to delays and partial cancellations.  Currently the people in charge are embracing bi-mode trains that can run on routes that are only partly electrified. --76.69.47.223 (talk) 08:50, 16 October 2018 (UTC)

On Saturday morning I watched the Flying Scotsman leaving King’s Cross. That was an experience, I can tell you. I haven’t really got close up and personal to a steam locomotive since they switched to diesel in the fifties. Meanwhile, the long-promised electric trains on our local line (the wires have been up for a year) have yet to materialise, and no-one has suggested a date when they will.

Just being picky but "The 1955 Modernisation Plan called for the phasing out of steam traction. Major withdrawals occurred during 1962–1966, and steam traction ended in August 1968" according to Steam locomotives of British Railways. I went from Paddington to Plymouth in 1965 by steam train. Alansplodge (talk) 10:25, 19 October 2018 (UTC)

Comparing a big ship diesel engine (due missing article see the German one: de:Schiffsdieselmotor) to an road vehicle diesel engine makes the ship diesel win the fuel efficiency. Taking a look on the rolling resistance, the rail will win by wunderful 2 % lost since decades ago, not to be compared to the losts of using an asphalt road and the railway has less stops which require to accelerate again. In a car, you will feel any trailer on the accelerator. Renewable energy has no efficient battery to make it mobile like a fuel can which allows to transport lots of energy in a small storage. --Hans Haase (有问题吗) 07:42, 21 October 2018 (UTC)

Innate responses to tastes

What evidence is there of innate human responses to tastes? For example, is there evidence of an inherent tendency in humans to dislike things that taste bitter? FreeKnowledgeCreator (talk) 22:40, 15 October 2018 (UTC)

Why it's called "bitter".[3] And the continued popularity of beer undermines your premise. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:35, 15 October 2018 (UTC)

No not really. You'll note my use of the word "tendency" in my question. Tendencies allow exceptions. FreeKnowledgeCreator (talk) 23:38, 15 October 2018 (UTC)

A lot of people drink beer. I don't. Why? Because of its bitter taste. But maybe I'm the exception. The problem with your premise is that it's switched around. It's called "bitter" because it tastes bad. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:50, 15 October 2018 (UTC)

Google "innate responses to tastes" and you'll see a number of options which may address your questions. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:58, 16 October 2018 (UTC)

talk page fodder
The following discussion has been closed. Please do not modify it.
This is a terrible answer. They aren't asking Google, they're asking us. Heaviside glow (talk) 19:47, 17 October 2018 (UTC) It's a better answer than your comment is. ←Baseball Bugs What's up, Doc? carrots→ 23:40, 17 October 2018 (UTC)

Humans have like other species special built-in reactions on taste and smell, but in some cases can train to overcome them like with beer or wine (which children do not like at all but adults even prize as Delicacy). Surströmming (fermented fish) is an exceptional example how build-in smells already even block us from trying to taste some food. Its likely because Homo Sapiens is not as able to devour rotten food without getting seriously sick as all Vultures and many Reptiles are naturally, because their "strong" Digestion is very capable of.

Checkout Americans Try Surströmming (Youtube 3:45) for a vivid impression--Kharon (talk) 04:26, 16 October 2018 (UTC)

Natural selection in action. In particular, bitter is usually indicative of plant toxins such as alkaloids. See Bitter taste evolution. Heaviside glow (talk) 19:44, 17 October 2018 (UTC)