These have resurfaced again in recent weeks.
As someone who is borderline fanatical about seeing Ireland evolve as a huge player on the global agri-food stage, sugar has been one of those products that intrigued me.
It draws raw material from the land, creates jobs and could help further boost the agri-food economy. It seems, intuitively, like a good idea. Unfortunately, hard economics concludes that the idea is a fallacy.
When considering new industries it is always worth analysing how the best in breed globally are doing. A perusal of recent investor presentations by the German sugar colossus, Sudzucker, is worthwhile in this regard.
Sudzucker has revenues of €7.7bn, 100 factories, 18,500 employees and has produced sugar since 1837.
As the No 1 sugar producer in Europe it has a 24% market share and owns 40% of the German sugar quota, 100% of those in Austria and Hungary, 72% in Belgium and a significant share in four other EU countries.
Despite this enormous footprint Sudzucker operating profit collapsed last year from €708m to €436m as sugar prices fell materially and it expects worse in 2014.
From a high of almost €550 per ton in 2012, sugar has fallen to below €350 as global stocks increased from 59m tons to 76m tons last year. Moreover, EU stocks have jumped from 1m tons in 2010 to 2.5m tons in 2013.
This situation is set to become even more volatile after 2017 when sugar quotas are to be abolished, reflecting moves afoot in milk. In dairying there is a strong argument that Ireland can survive post-quota as its grass-based production system is capable of absorbing bouts of weak pricing. In sugar the same does not apply.
Ireland has no comparative advantage in manufacturing sugar and is not well placed to develop export markets given the high weight-low price attributes of the sweetener.
Aside from current and uncertain market conditions there are also some uncomfortable truths about the long-term prospects for European competitiveness in a liberalised market.
Analysis by the University of Hohenheim in Stuttgart shows that sugar production costs in Brazil are about 15% of those within Europe. If free trade continues to unfold as a pattern worldwide it is the lowest cost producers who will gain. Even the mighty Sudzucker will find the going tough in such a scenario.
Against this backdrop anyone being asked to invest in a new sugar manufacturing project in Ireland should consider carefully the risk-reward ratios in such a capital intensive sector. Building a sugar refinery to provide a competitive offering would have to be large in scale in order to minimise costs.
If Ireland was such an obvious place in which a refinery should be built would not one of the large global players have already seized upon the opportunity? These may be tough conclusions but a clinical assessment is required.
Taking a much broader view of the Irish agri-food sector, where should we place our investment chips to have the greatest chance of sustainable returns?
I can see valid and well structured arguments behind milk and beef given the importance and advantages derived from grass production although both have considerable challenges of their own.
Seafood is facing a period of strong global demand and Ireland has natural advantages that have yet to be exploited. Compared to these the arguments made in support of revitalising sugar manufacturing are not convincing enough.
* Joe Gill is director of corporate broking with Goodbody Capital Markets. His views are personal