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Field test shows Volvo Buses’ plug-in hybrid reduces fuel consumption by 81% and energy consumption by 61%; 21 mpg

Volvo Plug-in hybrid_EN_2013
Volvo Bus’ plug-in hybrid. The pantograph for rapid charging can be seen on the roof. Click to enlarge.

Field tests being conducted in Gothenburg show that Volvo Buses’ plug-in hybrid reduces fuel consumption by 81% and total energy consumption (diesel plus electricity) by 61% compared to a comparable Euro 5 diesel bus. (Earlier post.)

The field test in Gothenburg began in June 2013 and includes three plug-in hybrid buses, the batteries of which are rapidly recharged at the terminals. This makes it possible for the buses to run on electric power for most of the route.

The plug-in hybrids are based on the Volvo 7900 Hybrid, Volvo Buses’ second series-produced hybrid bus model. The plug-in hybrids have been further developed, and enable rapid recharging from electricity grids via the Opbrid Bůsbaar pantograph on the roof.

The 4-cylinder, 5-liter Volvo D5F diesel engine produces 215 bhp and is installed vertically. The conventional hybrid offers up to 37% fuel savings compared to a diesel version and 40-50% lower exhaust emissions. The plug-in versions have a larger battery pack, making it possible to drive up to 7 km using electricity only—about 70% of the route distance. The batteries are charged at the bus terminus via the Bůsbaar for between six and ten minutes.

Our performance results are even slightly better than we had anticipated. The plug-in hybrid consumes less than 11 litres of fuel for every 100 kilometres [21 mpgUS]. That’s 81% less fuel than the equivalent diesel bus consumes.

—Johan Hellsing, Project Manager for the field test at Volvo Buses

In addition to the significant energy savings and reduced impact on the environment, this technology gives passengers a more comfortable and pleasant journey and improves the working environment of the drivers.

Although there are many long, steep gradients on the routes, the plug-in hybrid buses can run on electric power for about 85% percent of the time. The diesel engine only kicks in when the bus needs some extra power. The test drivers from GS Buss really appreciate the quiet, vibration-free ride that you get with an electric powered bus.

—Johan Hellsing

The field test of the plug-in hybrid buses in Gothenburg involves 10,000 operating hours and will continue for most of next year. A demo project that will bring eight more plug-in hybrid buses into service will commence next year in Stockholm.

A number of European cities are showing an interest in the plug-in hybrids. Hamburg and Luxembourg have already signed contracts for supplies of the buses in 2014 and 2015. Volvo Buses is working together with the city councils, public transport authorities and providers to develop long-term sustainable solutions for public transport. Volvo Buses plans to commence commercial manufacture of plug-in hybrids towards the end of 2015.

Those engaged in the plug-in hybrid project in Gothenburg are Volvo Buses, Göteborg Energi, Business Region Göteborg, Trafikkontoret and Västtrafik. The project is co-financed by Life+, the EU’s financing program for environmental projects.



Fuel consumption could be further reduced by adding more batteries. Doubling the batteries, to go from 7 Km up to 14+Km range would make it close to 100% electric in many cites.

With more batteries, the on-board ICE size could be further reduced?

Alternatively, the on-board ICE genset could be replaced with a lighter FC?


21mpg for a city bus is pretty darned impressive! Passenger mile per gallon is probably in the 250-300mpg range for a dense city.


GP... you have to add the electricity consumed. However, it would still be more efficient than the ICE versions.


Divide MPGe by 2 to get closer to reality.

EVs that say 100 MPGe are going on about 30 kWh per gallon of gasoline, as if the electricity came out of thin air. A 100,000 BTUs will create maybe 12 kWh of electricity at the power plant, by the time it gets transmitted, goes through the charger and round trip through the batteries, through the controller to the motor, that 100,000 BTUs might take you 40 miles.


Electricity in Sweden doesn't come out of thin air, but ~94% of it does come from clean sources (57.5% RE + 36.2% nuke) so replacing the fuel use with electricity has a much bigger effect there than it would someplace where coal is still king.


Actually, if you include the 3.4% that is imported from hydro dams in Norway, Sweden's grid would be 97% clean.


Volvo Canada has been developing PHEV and BEV city buses for more than 2 1/2 years. The first operational units should be tested in up to 12 Quebec Province cities in late 2014 or early 2015.

All local city bus purchases would then (from 2015 onward) be either PHEVs and/or BEVs. The transition will take about 12 years.


By 2015, the local electrified city buses would use clean electricity; about 95% from Hydro and 5% from Wind. By 2025 the mix may change to about 90% Hydro and 10% Wind.


I would add that the efficiency of this bus looks even better. Since it is cost competitive to produce diesel from pulp liquor in paper processing, and use cogen heat from coal or nuclear to do it, you have increased well-to-wheels energy loss avoidance. I speculate that the Thor Corp. plutonium/thorium reactor in Norway now initiated for a five year test could be the model for fuel cogen from timber. Plenty of timber in Scandanavia. Or use the chips to make methanol, which in diesel engines has as high an MPG as diesel, but virtually no emissions.

By the way, Norway has actually become a net importer of electricity despite those Norsk-Hydro dams, and has a lot of thorium.


You go 5 miles on electricity and 5 miles on a gallon of fuel and then claim that you got 10 MPG.


I enjoyed Europe on a Volvo bus decades ago and can only support their absolutely excellent products.


By the way, Norway has actually become a net importer of electricity despite those Norsk-Hydro dams

Yeah - "net"

Some parts of the country may import even while some others might export. Proximity of source to load matters, as does sesonal/yearly variation in rain fall.

Henry Gibson

Norway is one of the very largest contributors to CO2 releases, but it hides its releases by shipping methane and other petroleum to many other countries. A four foot diameter methane pipe goes to Germany or Holland.

Norway should immediately build several CANDU nuclear reactors and mix US "spent" fuel rod nonuranium actinides with 99 percent thorium to start operation. If just the remaining uranium from US "spent" fuel rods were made into CANDU fuel bundles they would have too much energy for now standard CANDU operation and it would have to be diluted with much thorium for standard operation as the Chinese have found out. The electricity can be sent to Germany to slow the deaths caused by breathing coal chemicals.

More people have been killed in wind turbine accidents than in nuclear reactor power plant failures. Not one person was killed by radiation after the Tsunami, but the fear mongering and relocations killed and will kill many. The natural potassium in every food organic or not, has long lived radioactivity in it.

It is too bad the world does not have a minor reactor failure in the Philippines to distract them from the thousands killed by water as was the case with tens of thousands in Japan. The death figures for oil production are only noted briefly except for platform sinkings but are much much larger than nuclear. Dam failures are very deadly and are the most dangerous. Coal mining has many disease deaths in addition to mining accidents and the public breathing chemicals from coal burning. Automotive fuel burning is a very large producer of death and disease.

It has been possible for over ten years to have plug in hybrid buses with clean operation by the use of ZEBRA batteries and turbines as shown on a bus builder website back then. A plug in bus, with first lead batteries and then ZEBRA batteries when the lead ones failed, delivered school children in California to their schools and home. It should have carried a small portable generator too; like a spare tire. ..HG..


I would see the main advantage being moving pollution from the city centre to the power stations, where fewer people live.

In the video, they talk about a hybrid bus for longer runs and a PHEV for inner city runs.

However, it all depends on being to park the bus while it charges for 5-10 minutes. This is the key - you need a space to park the bus under the charger, and you need the time to charge the bus - with a diesel bus you can just go straight away.

If the drivers take a break anyway, it won;t impact schedules so much.

@harvey, this is probably why they don't have a larger battery - it would take too long to charge.

Maybe they could increase the charging power now that Tesla has demonstrated that it can be done. Then, you could have a larger battery without impacting bus schedules too much.

There is also the cost aspect - they need to manage the costs or they end up with a jewel of a bus that nobody can afford.


HG...hand guns, machine guns and roads are very efficient killing machines (100,000/year) in USA. However, they can't match tobacco, junk foods, sweet drinks, pollution and man other man made industrial killers.

I have to agree with you that nuclear plants are no match for the above.


The opposition to nuclear power in Japan is not based on how many died or not, it's about the living. The living want to move on and get back to normal. As bad as the Tsunami was the clean-up and rebuilding was quick, 2 years later and most people had gotten back to normal. But the nuclear mess is still ongoing and they are told they'll be dealing with it for the next forty years.

Also there is the need to do something and the knowledge of what can be done vs what can't be done. The Japanese can't stop the Earth from shaking, but they can stop nuclear reactors from being built.


I have been working on this project for two years, so know it intimately.

The batteries on the bus are 28kWh, slightly larger than a Leaf. They use maybe only 8kWh on the run. The only reason it isn't 100% electric is that there are some steep hills on the route. This is a parallel hybrid, so the diesel turns on to help the electric motor up the hills.

This is an extremely flexible and robust solution to bus transport. Any combination of diesel and electricity can be used, depending on the route. And if there is a blackout or charger malfunction, then the bus keeps going. It also has a high passenger carrying capacity.

These buses are based on their high-volume 7900 hybrid bus, so prices should be quite reasonable. Expect to see this being a big sales winner for Volvo.


Well said ai_vin. I doubt that Japanese will soon return to more nuclear power plants. They may do like Germany and phase them out?

They will import CNG from many countries-producers and built more NG power plants. Secondly, Japan will install many more wind farms and solar (big and small) systems with storage facilities.

Opbrid...yes Volvo's PHEV and BEV buses will be mass produced soon. Given their historical high quality, they may very become worldwide top sellers.

Starting in late 2015 and early 2016, all cities in our Province will start replacing existing diesel city buses with Volvo Canada PHEV-BEV city buses. The complete transition for over 4000 buses will take about 12 years at the rate of about 400/year. The first batch may be PHEVs but BEVs will move in soon afterwards.

Quebec City has been operating a dozen pure electric buses for the last 5 years, to move tourists from lower-town to upper-town at a fixed $1 fee. Those small e-buses (15 to 20 pass) run a full 8-hour shift or about 100-110 miles on a single charge. It is amazing to see them climb the very steep hills with a full load. I don't know the batteries capacity but it could be a lot more than 30 kWh. Of course, the batteries recharge going down hill?

Bob Wallace

Japan is installing a lot of solar and is moving very rapidly toward a large offshore wind turbine industry.

On their windy, Pacific coast the water deepens quickly. Japan has been very aggressive in developing floating turbine bases. They now have two floating turbines on line.


Harvey, my city also has some electric bus routes, but they are trolleybuses (they get their power from overhead wires). We started building the system in 1948 and by '54 we had the largest trolleybus fleet in Canada (327 units). Nowadays the fleet is down to 262 but 74 are the bigger articulated vehicles.

We also have about 64 hybrids but this new PHEV system could allow us to reduce fuel use even more and that cost saving could make it more likely the rest of the diesel fleet will be replaced too.

However, I'm a fan of streetcars and would love to see the city put in some rail-lines and bring those back.


There are Bus Rapid Transit (BRT) corridors being built. With dedicated lanes for buses this could become popular, more cost effective and less disruptive than light rail.


Yes ai_vin, the 100+ trolley e-buses, operating on four or five major routes in our city were removed in 1952/54 after about 6 to 7 years of very successful operations. Icing on overhead power lines were a bit of a problem on a few winter days.

They were replaced with GM smoky diesel units.

Our trolley buses and spare parts were shipped to a large West Coast Canadian city, where similar trolley buses were in use.


There are Bus Rapid Transit (BRT) corridors being built. With dedicated lanes for buses this could become popular, more cost effective and less disruptive than light rail.

This is debatable. Buses aren't the only things that can be given dedicated lanes. Streetcars, if given dedicated lanes, aren't disruptive either. And they have lower operating and maintenance costs & longer service lives so the total effective costs are better.


They were replaced with GM smoky diesel units.

A big step backwards.

. . .were shipped to a large West Coast Canadian city

where they aided in a small step backwards: Our trolleybus system replaced our much loved streetcar system.


Autonomous e-buses, on dedicated lanes, could be very efficient and effective to move people in large cites and cheaper to install than subways and more esthetic than monorails and street cars?

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