Economy of Scale – the Secret of Sustainable Energy Solutions

The “Triple E” container ship

A few weeks ago Maersk presented the world’s largest ship to the public in Copenhagen. This very impressive container ship, which can load 18,000 containers, is of the “Triple E” class. Triple E stands for Economy of scale, Energy efficiency and Environmental improvement. According to Maersk, the CO2 emission of transporting 18,000 containers in this magnificent ship is as low as 3 g/ton/km, whereas it e.g. is 47 g/ton/km for a truck, which can carry around 3 containers. In other words, 6,000 times larger cargo reduces the cost by a factor 15.

The same “Triple E” principles are known from  the energy sector

A similar “Triple E” principle can be found in several of our energy technologies for cities. The more densely building stock and increased demand of concentrated energy in cities open for more cost effective, energy efficient and environmental friendly technologies. I can think of at least 3 significant ones.

Triple E” district heating pipes.

If a small building which has a heat demand of 100 MWh/year are to be supplied by a cheap heat source 1 km away, it will be very expensive. The small 25 mm pipe, which has the sufficient capacity, may cost up to 10,000 DKK/Km/MWh/year. In case the demand is 6,000 times larger, equal to 600,000 MWh/year, the cost of the required 600 mm pipe will only amount to 50 DKK/km/MWh/year in similar conditions. Thus, an increase of a factor 6,000 reduces the cost by a factor 200. The energy efficiency and environmental performance seem to be the same. The larger district heating system you have, the more energy efficient and environmentally improved heat sources you may be able to explore.

Solar heating

Solar water heating is the most efficient way to catch the solar energy. It can roughly catch 70 times more energy per Ha than e.g. corn, however the cost of solar heat depends very much on the size of the plant. The cost of heat from a 3 m2 plant at a single family house is at least 1,400 DKK/MWh, whereas the cost of solar heat from an 18,000 m2 large plant is only 200 DKK/MWh. Thus, an increase of a factor 6,000 reduces the cost by a factor 7. The energy efficiency and environmental performance will not change much.

Biomass boilers

Biomass, such as straw and wood, have been important energy sources ever since we managed to control the fire. Unfortunately, individual stoves and boilers for single family houses are inefficient and emits harmful emissions. However, by increasing the size by a factor 6,000 going from e.g. a 20 kW boiler supplying a single family house to a 12,000 kW boiler plant supplying a district heating system, the efficiency may increase by a factor 2 and the emissions may be reduced by a factor 100 or more. The price per kW will not change much.

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