Turbos, even diesel turbos, are associated with high rpm and rapid acceleration. It isn’t often that people talk about turbos in association with environmental consciousness and saving fuel. However, though it is true that turbos increase torque and acceleration, turbos are in fact technologies that increase fuel efficiency and reduce toxic engine emissions. 

Turbos are — contrary to what one might assume — green technologies.

In order to understand why turbos are such valuable technologies with respect to both the environment and the expenditures-versus-net gain of a business operation, it is necessary to understand what a turbo is, how it functions, and why what turbos do is different than almost every other mechanical device in auto engineering.

Understanding of Combustion to Understand the Value of Turbos with Respect to the Environment

Complete combustion of hydrocarbons — the combustible element of fossil fuels — produces only two emissions: carbon dioxide and water. Neither is toxic. Though carbon dioxide is often spoken of in the most negative of terms because of its association with global warming, in fact, carbon dioxide is as important as water with respect to the biosphere. 

Plants and organisms that use photosynthesis to convert solar energy into nourishment also require carbon dioxide. Photosynthesizing organisms use carbon dioxide in the same manner that animals and people use oxygen. Only in disproportionately high levels is carbon monoxide dangerous. The fact is, water vapor is more efficient at heating the biosphere — meaning it has a greater global warming potential — than is carbon dioxide.

Neither water nor carbon dioxide is dangerous unless they accumulate in the atmosphere in high concentrations, however, because both CO2 and H2O prevent thermal heat from escaping the atmosphere. Both carbon dioxide and water are greenhouse gases though neither is toxic  

But, emissions do contain extremely toxic gases and particles. The reason being, no engine burns the fuel completely. Unfortunately, no engine burns hydrocarbons even close to completely efficiently. Because of the shortcomings of human technology, toxic emissions like greenhouse gases; particulate matter; nitrogen oxides; carbon monoxide; sulfur dioxide; benzene; acetaldehyde; and 1,3-butadiene are components of fossil fuel exhaust. 

In addition to water and carbon dioxide and toxic emissions, exhaust also contains hydrocarbons. Hydrocarbons are the combustible element of all fossil fuels. The fact that engine emissions contain hydrocarbons means not only that engines don’t burn fossil fuels completely, engines do not burn a percentage of fossil fuels at all. 

The Reason Turbos are a Green Technology

The idea of 100 percent combustion efficiency is nothing more than a theoretical concept. All exhaust from every engine ever manufactured contains unburned and incompletely burned fuel.

The reason turbos have the potential to generate substantially more torque and acceleration than a carburetor or electronic fuel injection alone is that no engine has the ability to burn the fuel completely. No generator burns the fuel completely. No boiler or furnace burns the fuel completely. And no power plant burns the fuel completely. All emissions from fossil fuels contain things like particulate matter, carbon monoxide, toxic cancer-causing organics, greenhouse gases in addition to carbon monoxide and water, and hydrocarbons.

A turbocharger can increase the percentage of hydrocarbons that an engine does burn. But, a turbo increases the amount of fossil fuel a diesel (compression) or gasoline (spark-fired) engine burns. 

What are the Components of a Diesel Turbo and What Do They Do?

The name “turbo” is short for turbocharger. The turbocharger on a diesel is housed next to the exhaust manifold. It is composed of a turbocharger casing inside of which is found a shaft with a compressor wheel on one end and a turbine wheel on the other. The casing has four ports: exhaust inlet and outlet ports as well as an air inlet and outlet ports.

After exiting the piston cylinder and the exhaust manifold, the gases that result from combustion — exhaust — enters the turbocharger housing under great pressure. The pressure from the exhaust gases makes the turbine wheel spin. The kinetic energy produced by the effect of the exhaust spinning the turbine wheel also spins the compressor wheel because both the turbine wheel and the compressor wheel share the same shaft. 

The exhaust making the turbine and compressor wheels spin on the same shaft draws in air through the air inlet. The compressor wheel compresses the air and forces the compressed air into the engine through the air outlet port. The compressed air mixes with diesel and hyper-oxygenates it. 

Highly-oxygenated fuel burns considerably more efficiently than the oxygenation ration produced by a standard naturally aspirated engine.

Effects of a Diesel Turbocharger

At its most fundamental level, the purpose of a diesel turbocharger is to oxygenate diesel fuel with highly-compressed air. Oxygenating diesel fuel with compressed air increases the odds of the individual hydrocarbon molecules and molecule chains of oxygenating. The reason this is necessary is that — in its natural state — diesel fuel is not a homogenous mixture of fuel molecules. 

No fossil fuel is a homogenous mixture of hydrocarbons. Instead, fossil fuels are heterogeneous mixtures with clusters of molecule chains sticking together like micro-level galaxies. Fuel molecule cluterization is the biggest reason fossil fuels do not combust completely. And, fuel molecule clusterization is a much larger issue in fuels with high energy density. 

As diesel has one of the highest energy densities of any fossil fuel, diesel has a high combustion efficiency rate. The reason that fuels with high energy densities do not combust as completely as cheaper less valuable fuels — natural gas, for example — is because while all hydrocarbons are made of carbon and hydrogen, how those two elements combine to form molecules and molecular chains vary radically. 

Why Turbochargers are Particularly Effective at Increasing Fuel Efficiency and Reducing Emissions for Diesel Engines

High-energy density fuels like diesel have a high ratio of carbon to hydrogen. Fossil fuel hydrocarbons in low-energy-dense fuels like natural gas (methane) have a 1-to-4 or 1-to-5 carbon to hydrogen atom ratio. High energy dense fuels like diesel have ratios closer to 1-to-2. But, though a good thing in many respects, high energy density fuels with high carbon to hydrogen ratios are extremely stable. 

Fuel stability is an expression used to describe the difficulty of combusting a fuel. Low energy, highly homogenized fuels like natural gas and propane are highly volatile meaning they ignite easily. A single match is sufficient to combust low-density fuels. However, it is much more difficult to get high energy fuels to combust. Using a single match to combust coal is virtually impossible. The odds of igniting a gallon of diesel with a single match are only slightly greater. 

While fuel stability is an excellent quality with respect to safety and pre-combustion emissions — fuels that are high in energy density evaporate at much lower and slower rates than low energy dense fuels — fuel stability is also the reason fossil fuels with high energy density burn incompletely and produce a large number and wide variety of emissions.

That is to say, fossil fuels that are high in energy content are not dirtier than other fossil fuels; it is simply that we have yet to produce an engine, furnace, or boiler capable of producing a complete burn. 

And that is where a turbocharger comes in. A turbo increases the efficiency at which diesel — an extremely stable and high energy-rich fuel — combusts. By increasing the combustion efficiency with which an engine burns diesel, a turbocharger increases the amount of energy diesel produces and reduces emissions by converting a greater percentage of diesel fuel into carbon dioxide or water as opposed to a toxic emission. 

Fuel Catalysts: the Turbocharger Counterpart

While a turbocharger is an extremely efficient means of increasing fuel efficiency and reducing emissions — because turbochargers hyper-oxygenate fuel, — they are not the only means of increasing the oxygen that reaches the hydrocarbon molecules in a fossil fuel. Diesel fuel catalysts achieve the same end, using the same means, but with a different process. 

A fuel catalyst is composed of the same components as a catalytic converter, namely, noble metals. However, a diesel fuel catalyst is a pre-combustion mechanical device — like a turbocharger — that conditions fuel prior to combustion. And, while a catalytic converter only reduces the emissions from an engine, a diesel fuel catalyst increases fuel efficiency. 

One of the most valuable aspects of turbochargers and fuel catalysts is that unlike catalytic converters, diesel fuel catalysts and turbos also increase fuel mileage. And, both use oxygenation to achieve that end. But, while a turbocharger increases oxygenation ratios using compressed air — like those found in a catalytic converter — a diesel fuel catalyst uses noble metal catalysts. 

A turbo agitates fuel molecules, hydrocarbons, with compressed air in order to increase oxygenation potential. A diesel fuel catalyst depolarizes hydrocarbon molecules and molecule chains in order to break up the fuel clusters.