Software for Renewable Energy Processes-5

Bela Liptak Describes the "Battery Swap"-Based Transportation and the "Energy Free" Housing He Sees for the Future

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By Béla Lipták, PE, Columnist

In this fifth article of this series, I will describe the "battery swap"-based transportation and the "energy free" housing that I visualize will be used by the end of this century. Automation and optimization of these processes will expand the role of process control beyond the present industrial applications as they will also be needed for motor, charger and fuel cell controllers in transportation and RFC, PV array, charge, back-up and bi-directional meter control and optimization to guarantee safe and efficient operation. For all the parts of this series of articles refer to www.controlglobal.com/voices/liptak.html or http://tinyurl.com/2g3bn9r.

Transportation of the Future

The car manufacturers have not yet decided if the future belongs to the all-electric car, the hydrogen fuel cell, the hydrogen-burning internal combustion engine, the multi-fuel vehicle or some combination of these, but whichever technology comes out on top, control software must be developed to guarantee its safe and efficient operation. The race comes down to cost.

The advantages of the all-electric vehicles (EV) include their relatively low fuel cost (today's cost of a gallon of gasoline buys about 100 miles of electric driving), their limited needs for new infrastructure and the fact that they emit no CO2. Their main disadvantages are their higher price (in the low $30,000s), their weight, limited driving range (Figure 1), long charging time, short battery life and small cargo space. For example, in the case of the Nissan Leaf, the price is $32,780, which is reduced to $25,280 after the U.S. federal tax rebate of $7,500 is considered, and in some case, such as in California, it is further reduced to $20,280 by an additional $5,000 tax rebate.

The standard charging time, if the car is charged at night in one's garage, is three to four hours. High-speed charging, using three-phase industrial outlets, can reduce the charging time to 10 to 20 minutes. "Battery swap" at service stations can further reduce this time to a couple of minutes.

It seems that after fossil fuels are exhausted, hydrogen will play a key role in transportation. It is not clear yet if the hydrogen will be charged into the individual cars at the fuel stations, or if it will fuel large fuel cells at the station that will generate the electricity to recharge the depleted batteries of all-electric cars. This will be an economic decision.

Today, economics favors the batteries, but even then, battery costs are still high, amounting to a quarter to half of the total cost of the car, depending on driving distance. In terms of energy density, lithium (Li-ion, Li-poly) and zinc-air batteries are the best today, but the availability of both of these materials is limited. For example, the lithium reserves of the planet for example are sufficient for about 4 billion electric cars.

In the long range, these reserve limitations can be overcome by using hydrogen-fueled cars. There already is a fair amount of experience with hydrogen-based transportation. In Berlin, 20% of the buses run on hydrogen. In Iceland, hydrogen-fueled rental cars are offered by Hertz. In Japan, hydrogen-fueled commuter trains are in operation. In Italy, one finds hydrogen-powered passenger ships. In Russia, hydrogen-fueled airplanes are used. And, the U.S. Air Force and NASA are jointly developing a hydrogen-fueled, earth-orbit airplane.

I visualize that by the end of the century, the filling stations might have large, underground, double-walled, cryogenic hydrogen storage tanks, supplying hydrogen to large fuel cells that will be converting the chemical energy in liquid (or high-pressure) hydrogen into the electricity needed to recharge the depleted batteries of electric cars. To reduce the refueling time to a minute or two, the depleted battery blocks will simply be swapped with recharged batteries.

Housing of the Future: The Zero Energy Homes

About half of all family homes on the planet could become fully (the others partially) energy-independent if they were covered with PV type solar collectors or solar shingles. By the end of this century, homes and other buildings are likely to have gabled roofs to maximize the south-facing roof area, and thereby maximize the efficiency of energy collection.

Solar shingles are also called building-integrated photovoltaics (BIPVs) because they are made of photovoltaic materials, and can be used to replace conventional shingles that provide only cladding for the home. Solar shingles can also be used on window overhangs, on the windows themselves (glazing), and on the siding of the home.

One design is available at 12 in. by 86.5 in., which can be nailed to the roof decking over a felt sheeting. From the underside of each shingle, 12 in. of  #18AWG wires extend, and pass through the roof deck to make the electrical connections.

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