by Greg Simpson

Going green’s a gas

Can the green gas solve our future energy crisis?

Truck in transet
Going green’s a gas.jpeg

Keeping these growing mega-cities supplied in an ecologically sustainable way is one of the crucial problems facing urban and regional planners today. In the hunt for efficient alternatives to fossil fuels, Volvo Trucks’ latest green solution, the biofuel DME (dimethyl ether), may well play an important role.

Forward-planning researchers are scarcely renowned for their unanimity on any issue, but on one point they are all in firm agreement: the world is moving toward the mega-city. Even today, there are more people living in large urban environments than in rural areas, and in another 25 years no less than 70% of the world’s population will be living in mega-cities. Within that space of time, it is estimated that the world’s total building density will have doubled. 

This swift urbanisation means the world’s urban and regional planners are facing gigantic challenges – not least on the issues of the environment and climate, since fast growing cities impose considerable burdens on both.

The United Nations’ aim of limiting global warming to two degrees Celsius has been adopted as the norm in this context. The European Union has promised to reduce emissions of greenhouse gases by 20% before 2020 – increasing that figure to 30% if other countries toughen their eco-targets. The same trend can be seen elsewhere in the world.

The question of how today’s metropolitan centres can continue to grow, bearing in mind these increasingly tough targets, is answered by the experts with two words: increased density. After having grown laterally for decades, tomorrow’s major cities will now start growing inward, toward the centre.

“With a denser population structure, people have access to a wider variety of services and facilities within a shorter range. This, in turn, reduces travel requirements and increases the use of sustainable transport methods such as walking and cycling,” says Sverker Hanson, civic engineer and transportation planner at international consultancy, Sweco, in an official press release. 

He continues: “The same advantages of increased population density can be seen with regard to logistics. There is already a trend toward a greater number of distribution terminals in and around major cities. With more densely populated cities, in the future it may be possible to have one large reloading terminal per district, with electrically powered distribution trucks providing just-in-time delivery services to households and companies.”

Other trends are the co-ordination of long-haul and distribution transportation, and the creation of public transport for goods. However, increased population density and increasingly well thought-out – and environmentally optimised – urban centres will not solve the other major problem facing the planners: how tomorrow’s mega-cities will be kept supplied. The mathematics is simple: more people means a growing need for consumer goods and food – and a radical increase in the need for transport into the cities.

“We are moving toward a situation where many of our fossil fuel reserves, such as oil and natural gas, are beginning to dry up. This, together with increased demand for energy, will lead to rising energy prices. Linked to the climate issue, this means that the key for tomorrow’s transport will be energy efficiency,” says Lars Mårtensson, environmental affairs director at Volvo Trucks.

He feels that tomorrow’s transport infrastructure must be based on increased synchronisation of existing transport methods. Ships, railways and trucks will need to work side by side. 

“The future is with a wide variety of transport methods. What we need to work on is improving the synergies between them. This is an area in which we have considerable potential for improvement,” explains Mårtensson.

DME is a gas that is transformed into a liquid under low pressure, so it is relatively straightforward to handle. It is used today for a variety of purposes, among others as a propellant in spray cans, as a fuel in cigarette lighters and as a base chemical in the production of plastics.

DME can be produced both from natural gas and from a variety of biomass sources, in which case it is known as Bio-DME. 

As a fuel in a diesel engine, DME provides as high an efficiency rating as a traditional diesel engine, but at a lower noise level. The combustion process produces no soot, so a far simpler method of after-treating the exhaust gases can be used. Furthermore, the engine can produce higher torque when starting off, thus improving driveability.

Minnet Media

Facts about DME

• DME is a gas that transforms into a liquid under low pressure. It can be handled more or less like liquefied petroleum gas. Today, DME is primarily used as a propellant in spray cans.

• DME can be produced from natural gas and from various forms of biomass. According to European Union estimates, by 2030 Bio-DME can potentially replace more than 50% of the diesel oil currently used for heavy road transport. 

• When Bio-DME is made from biomass via black liquor in a pulp plant, the result is 95% lower carbon dioxide emissions compared with fossil diesel. At the same time, it is five times more efficient than biodiesel in terms of the transport kilometres obtained from each hectare of land used for cultivation of the raw material.

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Issue 2020