# Developments in Electric and Green Marine Ships
## 2 Legislation about GHGs, Sulfur, and Other Laws Affecting Maritime Industry  
Approximately 90% of world trade (by volume) is transported by the global shipping fleet. It is no surprise that thousands of ships performing this vital task burn vast quantities of marine fuels for propulsion and on-board electrical power. For example, a Pure Car and Truck Carrier (PCTC) may consume between 30-60 tons of fuel per day, depending on its operating speed and weather conditions. On a global basis, it is estimated that between 2007-2012, ships consumed on average approximately 250 million to 325 million tons of fuel per year, resulting in approximately 740-795 million tons of CO\({}_{2}\) emissions. Another estimation is that in 2007, CO\({}_{2}\) emissions from 45,620 vessels amounted to 943 million tons, with the total fuel oil consumption (FOC) being 297 million tons [29; 30]. In addition to CO\({}_{2}\) emissions, a range of other substances, including NOx, SO\({}_{\chi}\), and particulate matter (PM) are released into the atmosphere as a result of global shipping activity. These substances have an adverse impact on human health, contributing approximately 60,000 deaths per year. In the top 50 ports alone, approximately 230 million people are directly exposed to emissions from shipping [31; 32; 33]. The main reason behind the relatively high level of emissions is the composition of the marine fuels. However, emissions should be taken under consideration, even when liquefied natural gas (LNG) is used as a fuel source. In recent years, organizations including the International Maritime Organization (IMO) and European Commission (EC) have taken actions to reduce airborne emissions from the shipping sector via policy initiatives. These include the implementation of Emission Control Areas (ECAs), the setting of sulfur content limits in marine fuels, and the International Convention for the Prevention of Pollution from Ships [34]. These policy initiatives have encouraged the development and adoption of various eco-friendly technologies and measures. Bringing these matters to the present, the global maritime industry is embarking on a major overhaul of its fuel supply. Starting from 1 January 2020, under the IMO's International Convention for the Prevention of Pollution from Ships, MARPOL treaty, it will be required that all fuels used in ships contain no more than 0.5% sulfur [35]. The cap is a significant reduction from the existing sulfur limit of 3.5%, and is well below the industry average of 2.7% sulfur content. Carriage of non-compliant fuel oil for combustion purposes, propulsion or operation on-board, is prohibited, unless the ship has an exhaust gas cleaning system (scrubber) fitted. Installing a scrubber is accepted as an alternative means to meet the sulfur limit requirement, which benefits the environment and human health. A submitted study to the IMO's Marine Environment Protection Committee (MEPC) in 2016 estimates that by not reducing the SOx limit for ships from 2020, the air pollution from ships would contribute to more than 570,000 additional premature deaths worldwide between 2020-2025. As far as GHGs are concerned, the IMO is also taking early steps to reduce them. In April 2018, the United Nations (UN) agency reached a deal of great importance, on curbing carbon emissions from ships by at least 50% below 2008 levels by 2050. The non-binding agreement is expected to attract investment in clean ship technologies, including fuel cells, biofuels, and advanced sail designs. However, for the time being, shipping companies are focused on the impending sulfur cap, but switching fuels won't be as simple as selecting a higher grade of gasoline at the pump. Low-sulfur alternatives are generally more expensive and less widely available than bargain-rate bunker fuels. In some corners of the industry, this has led to negative forecasts of fuel shortages and spikes in cargo rates.