One of the most exciting point-of-use emerging technologies is
that developed by Moteur Development International (MDI). MDI’s technology has
received much publicity (because of the famous “air car”) without its
importance being well understood.
Dr Louis Arnoux considers
that the MDI technology, has the potential to be used as a catalyst for the radical
transformation of point-of-use energy systems as well as for the revolution of
all forms of transport. That is to say, the MDI Technology enables the extremely
cost effective harvesting of solar energy, mostly on the customer’s premises,
and the close matching of the qualities and quantities of energy supply and use
at their point of use. It has the potential to enable achieving the objective of
shifting from less than 20% to over 80% energy efficiency in a competitive
market-wide fashion. It is for this very reason that
IndraNet Technologies has invested
significant time and resources into assisting MDI in it’s development and commercialisation effort as part of their aim of developing a cost-effective
converged ICET package for the emerging Post-Oil, Solar Era.
The MDI Technology encompasses four components: the MDI
Compressed Air Engine, the MDI Power Generator, the MDI Transport Applications
and the MDI Manufacturing Process.
MDI Compressed Air Engine
Unlike petrol or diesel engines, the MDI technology does not use
any form of internal combustion. Instead, it incorporates four key breakthroughs.
, the use of compressed air (or other gases or
combination of gases) as energy carrier and storage medium.
Compressed air is a clean, low cost and efficient form of energy
storage. MDI uses pressures of around 300 bar in carbon fibre composite storage
cylinders. As an energy carrier, compressed air is used at 30 bar or less to
push pistons in the MDI engine.
Second, the primary energy input is taking place outside the
engine by the heating of compressed air (or other gases, such as combustion
Physics tells us that heating a gas at constant pressure results
in its expansion. In the MDI power block that incorporates the MDI compressed
air engine, the heated, compressed air and/or combustion gases expand by a
factor of three to five.
Moving the energy input from inside an engine to the outside
provides a wide range of substantial advantages. High temperature explosions
inside the combustion chambers of internal combustion engines result in the
production of nitrogen oxide gases (NOx), uncombusted volatile organic compounds
(VOCs) and particulates (soot).76 Instead, in the MDI system combustion takes
place in a steady state fashion at much lower temperatures (typically less than
900°C) in an excess of oxygen. The combustion is “lean and clean”, with near nil NOx, uncombusted
particulates or VOCs, and if biofuels are used, it is also “green”.
For mechanic buffs here, in essence, is how an MDI Engine works
when configured to operate in a multi-fuel mode. With the inlet valve open
compressed air at 30 bar pushes the smaller of the two pistons during its entire
down stroke while the larger piston stays put at the top of the two piston
chamber (it can stay like that because of the special configuration of the
connecting rod). The inlet valve is then shut and the compressed air located on
top of the first piston and in the active chamber common to both pistons now
expands and pushes the second larger piston. When the latter is all the way down
the pressure is about 1.2 bar and the air exhausts into the atmosphere on the
upstroke of that larger piston.
The larger piston is also associated with a small extension on
top of it that functions as an air compression piston used to produce the
initial volumes of compressed air that are then expanded by heating outside the
engine. On the down stroke of the larger piston air is “breathed in” and
on its upstroke the larger piston causes the air compression piston
to compress the air intake to 30 bar and push it through the
external heater/combustor where it will be heated at constant
This heating at constant pressure expands
the compressed air by a factor of 3 to 5 before it is injected on top of the
The functioning of the MDI active chamber, as described above,
achieves twice the amount of work produced in an ordinary internal combustion
engine, for the same amount of compressed gas used to push pistons. Put another
way, the combination of two pistons pushes on the crankshaft over 270 degrees
rotation instead of just 180 degrees.
The MDI active chamber also means that the engine’s torque curve
is very flat, that is, the torque and engine efficiency both remain essentially
the same from very low to high revs. This allows for much simplified clutch and
gear box components in the case of automotive applications and substantially
higher performance for point-of-use power generation applications.
Furthermore, the heating of the compressed gas stream can be
achieved through a wide variety of means including the combustion of fossil or
biofuels, the recycling of waste heat from other processes, or the use of direct
or indirect solar energy, all carried out in low cost, highly efficient and
environmentally sound fashions. Ordinary engines are devoted to one type of
fuel. A diesel engine only burns a diesel type of fuel. Most petrol engines can
only accommodate a maximum of 10% ethanol without risking substantial damage.
The MDI engine can accommodate any type of fuel. For example, bio-oils do not
have to be refined into biodiesel. Ethanol can contain significant traces of
water without this being a problem. This means that one can begin to use those
higher efficiency engines well ahead of biofuel supply chains being fully in
place and thus achieve a smooth transition from fossil fuels to biofuels.
Third, the MDI Active Chamber (incorporating two pistons per
modular engine head).
The MDI Active Chamber enables the energy efficiency of an
engine, relative to an internal combustion engine, to be more than doubled (see
Fourth, “Cool Combustion” using the Giant Magneto-Caloric
Effect to drastically cool the air (or other gas) intake.
The use of GMCE, dubbed “Cool Combustion” by MDI, aims,
when implemented, to achieve further substantial energy efficiency gains. Much
less work is required to compress to 30 bar the substantially cooled air. The
drastic cooling of the air also substantially reduces the temperature of the
primary energy input at the level of the heater-combustor to below 350°C. This
means that biofuel requirements are greatly reduced. It also means that a wide
range of other sources of relatively low-grade heat can be used, including the
advanced forms of thermal solar.
The fully configured MDI engine (as diagrammatically
opposite) combines the four above breakthroughs with the use of heat
exchangers enabling solar energy inputs from both direct thermal solar and also
from the ambient heat stored in the atmosphere (as we have seen earlier, this is
the largest source of solar energy on Earth).
The MDI Active Chamber alone results in around 40% energy
“solar augmented cool combustion”.
The integration of the Cool Combustion and solar heat exchangers are
expected to increase efficiency to over 80%. Efficiency here means energy output
versus purchased energy input. Those high efficiency levels do not contradict Carnot Cycle maxima since the MDI power block combines a compressed air (or
other combustion gases) engine with a GMCE heat pump (or more specifically an “entropy pump”). In this configuration, the system extracts and mobilises
solar energy stored in the atmosphere as ambient heat, hence the label of
The implementation of solar augmented cool combustion, in
commercial versions of the engine, offers the prospect of a drastic reduction in
fuel requirements. For vehicles, the prospect is a progressive reduction in fuel
uses from the present level of around 2.5 litres per 100km in the current engine
model down to 1 litre per 100 km or less through a planned series of new engine
releases and upgrades.
MDI Power Generator
MDI has also developed a variable speed point-of-use power
generator designed to be fully integrated with its advanced compressed air
The generator makes full use of the near constant torque and
efficiency of the engines at a wide range of rotation speeds. The electronics
operating the system sense the point-of-use power demand and power the generator
up or down to constantly match that demand. This means that only the minimum of
fuel required is used at any time.
Through a series of product and service releases, this
technology has the ability to shift domestic, commercial and industrial energy
costs from current retail costs in the order of AU$0.15 to $0.20 per kWh to
below AU$0.10/kWh and then to substantially below AU$0.05/kWh in parallel with a
progressive shift towards 100% solar energy as the primary energy source and
100% sustainable outcomes. Similar orders of magnitude also apply to the use of
the MDI technology for land, sea and air based transport.
Reproduced with kind permission of Dr Louis Arnoux from his e-book
"Peak Oil, Climate Change & All That Jazz"
Compressed Air Engines
MDI Compressed Air Engine
Based on the new MDI thermodynamic cycle.
External heat source combined with compressed air as the energy
carrier and storage medium.
Air storage pressure 300 bar, engine operating pressure 30 bar.*
Efficient, clean and clean external combustion, multi-fuel capable,
competitive use of biomass fuels and direct
Surplus power used to recharge the compressed air storage.
Overall energy efficiency more than twice that of internal
combustion engines and
capable of reaching over 70%.
Enables impressive cost reductions for manufacture, operation and
maintenance of low cost, zero emission vehicles and
environmentally sound distributed power generation.
This compressed air engine reached
international recognition in February 2007 when Tata Motors Ltd of
India announced it had concluded an agreement with MDI to apply the
MDI technology to its Indian markets, corroborating that the MDI
technology has the potential to open up the way to the rapid and
highly competitive commercialisation of alternatives to oil and
other fossil fuels for electrical power and transport.
The MDI Engines are protected by many
patents registered worldwide. They consist of an active chamber and
are made up of modules of two opposing cylinders. These modules can
be coupled to make groups of 4 or 6 cylinders for a wide range of
uses from 4 to 75 hp in the following applications:
MDI AIROne and
AIRCity Clean Cars
The MDI AIRMulti Urban Transport System
Electricity Power Generators and Emergency Generators
Tow Tractors, Pallet Trucks and Hoists
Light Aircraft Engines and APU units
Based on this new Technology,
MDI is now in the process of developing a
“thermodynamic concept” that will enhance these results even further,
over the next ten years, thus initiating a genuine
1 to 3 bar, Scuba tanks 150 to 200 bar, Air Car tanks
300 bar - hence the need for special air compressors
Saturday January 12, 2008
By Pierre Thebault,
CARROS, France --
interview with Guy Nègre he explains -
car that runs on air?
What seemed like a pipe dream may soon become reality, as
Frenchman Guy Nègre hopes versions of his compressed air car
will be produced in India this year by Tata Motors.
follows a 15-year quest for backers for his invention.
Nègre believes the time is right for his design with oil prices
at record highs and pressure on carmakers to improve the fuel
efficiency of their vehicles.
"It is clear that with oil at US$100 ($130) a barrel this
will force people to
change their use of fuel and pollute less," Nègre said at
his firm Motor Development International (MDI), near Nice in the
south of France.
car is zero pollution in town and almost no pollution on the highways,"
he added, saying the vehicle could travel 100km at a cost of €1 ($1.88)
former Formula One motor racing engineer's invention depends on
pressurised air to move the pistons, which in turn help to compress the
air again in a reservoir.
engine also has an electric motor, which needs to be periodically
recharged, to top up the air pressure.
bottles of compressed air - similar to those used by divers - can be
filled up at service stations in several minutes.
latest versions of the cars - MDI made an entire series of prototypes of
engines and vehicles - also include a fuel engine option to extend the
car's range when not in reach of a special power plug or service
Tata, India's largest carmaker with revenue of US$7.2 billion in its
last financial year, concluded a deal last year investing €20 million .Pre-production in India is set for this year, Nègre said.
vehicle, protected by some 50
patents, will cost €3500 to €4000. Using
composite materials, it will weigh no more than 330kg and its maximum
speed is 241km/h.
"The lighter the vehicle, the less
it consumes and the less it pollutes and the cheaper it is. It's
simple," Nègre said.
He aimed to set up
mini factories in regions where the car is used. "No transport, no
parts suppliers. Everything will be made at the place of sale in
production units that can make one car per half hour," said
"That is more profitable, more ecological than the big factories
of the large carmakers."
MDI Air Car will hit the
roads of India and Australia first, France will have to wait