Heavy-duty trucks, such as the 18-wheelers that transport many of the world’s goods from farm, factory, or port to market, are virtually all powered by diesel engines. They account for a significant portion of worldwide greenhouse gas emissions, but little has been done so far to curb their exhaust. Now, researchers at MIT have devised a new way of powering these trucks that could drastically curb pollution, increase efficiency, and reduce or even eliminate their net greenhouse gas emissions.
该概念涉及使用插电式混合动力发动机，其中卡车将主要由电池提供动力。该发动机将使卡车方便地行驶与当今传统的柴油卡车相同的距离，它将是弹性燃料模型，可以在纯汽油，纯酒精或这些燃料的混合物上运行。
While the ultimate goal would be to power trucks entirely with batteries, the researchers say this flex-fuel hybrid option could provide a way for such trucks to gain early entry into the marketplace by overcoming concerns about limited range, cost, recharging times, battery disposal, or the need for heavy batteries to get a long range.
新概念是由MIT Energy Initiative和Clasma Fusion and Science Center的研究科学家Daniel Cohn以及首席研究工程师Leslie Bromberg开发的。
“We’ve been working for a number of years on ways to make engines for cars and trucks cleaner and more efficient, and we’ve been particularly interested in what can be done with spark ignition as opposed to the compression ignition used in diesels because it’s intrinsically much cleaner,” Cohn says. Compared to a diesel engine, a gasoline-engine produces only a tenth as much nitrogen oxide (NOx) pollution, a major component of air pollution.
此外，通过使用弹性燃料配置，使它们可以在汽油，乙醇，甲醇或这些混合物上运行，此类发动机可能比纯汽油发动机少得多，并且燃料灵活性的增量成本很小，小，根据科恩和布罗姆伯格的说法。如果用纯甲醇或乙醇源自可再生能源（例如农业废物或市政垃圾），则净温室气体排放甚至可能为零。科恩说：“这是一种可用时使用低绿室气体燃料的方法，但始终可以选择用汽油运行以确保最大的灵活性。”
“Although Tesla Motors has announced it will be producing an all-electric heavy-duty truck,” Cohn says, “we think that’s going to be very challenging, because of the cost and weight of the batteries needed to provide sufficient range.”
To meet the expected driving range of conventional diesel trucks, Cohn and Bromberg estimate it would require somewhere between 10 and 15 tons of batteries “That’s a significant fraction of the payload such trucks would otherwise carry,” Cohn says.
To get around that, Cohn and Bromberg will use though a plug-in hybrid. The engine they propose for such a hybrid is a version of one the two researchers have been working on for years, developing a highly efficient, flexible-fuel gasoline engine that would weigh far less, be more fuel-efficient, and produce a tenth as much air pollution as the best of today’s diesel-powered vehicles.
科恩（Cohn）和布罗姆伯格（Bromberg）对开发这种引擎的工程和经济学进行了详细的分析，以满足现有卡车运营商的需求。他们发现，为了匹配柴油的效率，可以使用酒精与汽油甚至纯酒精的混合物，并且可以使用可再生能源来处理。详细的计算机建模，包括一系列所需的发动机特性，并使用人工智能筛选结果，对最有希望的途径进行了明确的迹象，并表明这种替代确实在实际和财务上是可行的。
In both current diesels and proposed flex-fuel vehicles, emissions are measured at the tailpipe after a variety of emissions-control devices have done their work, so the comparison is a realistic measure of real-world emissions. “Combining a hybrid drive and flex-fuel engine introduces electric drives into the heavy truck sector by making it possible to meet range and cost requirements, and doing it in a way that’s clean, Cohn says.
Bromberg says that gasoline engines have become much more efficient and cleaner over the years, and the relative cost of diesel fuel has gone up, so that the cost advantages that led to the near-universal adoption of diesels for heavy trucking no longer prevail. “Over time, gas engines have become more and more efficient, and they have an inherent advantage in producing less air pollution,” he says. And by using the engine in a hybrid truck, it can always operate at its optimum speed, maximizing its efficiency.
“Methane is an extremely potent greenhouse gas, so if it can be diverted to make a useful fuel by converting it to methanol through a simple chemical process, that’s one of the most attractive ways to make a clean fuel,” Bromberg says. “Alcohol fuels overall have a lot of promise.”
他指出，加利福尼亚已经制定了有关卡车排放的新法规，这些规定很难与柴油发动机车辆相遇。科恩说：“我们认为卡车运输公司可以去汽油或弹性燃料是有重要的理由。”“发动机更便宜，排气处理更便宜，并确保它们可以符合预期的法规。鉴于不断清洁的电网，将其和电动推进结合在混合动力卡车中，应减少货运部门的排放和污染。”
科恩说：“卡车的纯电动推进是最终的目标，但今天的电池还没有成为现实的选择。”“电池很棒，但让我们对其可以提供的东西保持现实。”
