There is a huge push for green energy these days. It seems everyone is looking for a vehicle that is non-polluting, goes many miles per tank/charge, requires no maintenance, has plenty of room for occupants and gear, great performance, low initial cost, low operating costs, and a high residual value.
The first step-up bicycles, the original police vehicle, the greenest of all police vehicles, are personal motorized vehicles. These include the two-wheeled and three-wheeled motorized personal transportation, along with a huge variety of scooters and motorcycles. The two-wheeled and three-wheeled personal transporters have the advantage of the officer riding high to view over the crowds.
The transporters have the speed for a rapid response to most any situation. These vehicles do well in crowded areas, such as malls, airports, parks, and schools. They also function well in closed environments where emissions and noxious fumes can be troublesome, such as in an enclosed mall.
However, the downside is the patrolling surface must be reasonably smooth and level. One university police department who tested this type of patrol vehicle found they did not fare as well on rougher surface streets or on hilly terrain. Inclement weather is another downside, and so is battery life. Of course, when the battery dies, the officer is stranded. One chief noted that some officers assigned personal mobility devices complain of back issues from all the standing while driving.
Today, most patrol vehicles are gasoline-powered engine. Recent developments have greatly improved the efficiency of these engines: 4-valves per cylinder, Variable Valve Timing, cylinder deactivation under light loads, turbocharging, direct fuel injection, and dual or variable valve lift and duration have produced the trifecta of better mileage, more performance, and fewer emissions. However, they still use gasoline, and in some people’s mind, nothing using gasoline can be green.
The next green step up from gasoline is, of course, the hybrid electric vehicles. Hybrids come in many forms. Some gasoline-powered vehicles with massive starter motors and batteries use Stop/Start technology. Called ‘mild’ hybrids, gasoline is still used to propel the vehicle, but the engine is seamlessly shut off and restarted during deceleration and at a stop.
The ‘full’ hybrids, on the other hand, use a combination of an electric motor and a gasoline engine to propel the vehicle. Using a very complex powertrain logic, these vehicles typically run on the electric motor at low speeds, where electricity is the most efficient, and on the tiny gasoline engine at higher speeds, where gasoline is the most efficient. They can also run on both the motor and the engine, as the demands require. Some hybrids are almost true electric vehicles with a tiny gasoline engine simply used to recharge the batteries, while others use the gasoline engine to propel the vehicle.
Next up the green ladder are the gasoline-free, plug-in Electric Vehicles. These are totally electric, period. You plug them in to 110/120-volt household outlets or 220/240-volt charging stations to charge the batteries. The advantages include very low operating costs, excellent performance, and zero emissions (from the vehicle).
The disadvantage of the electric vehicle is the same as the advantage—the batteries. While battery technology is steadily improving, batteries are still big and heavy, which compromise storage space. Complete recharging can take hours, which will take the vehicle out of service while it is being recharged.
Another disadvantage is infrastructure. The 110/120-volt outlets take a long time to recharge. The 220/240-volt chargers are much more efficient and faster. Cities with green initiatives know they must go to the expense of placing 220/240-volt Electric Vehicle charging stations throughout the city. As of now, the plug-in electric vehicle is well-suited for some aspects of patrol use within a small radius, such as administrative or investigative duties.
There are a number of well-known, but possibly misunderstood, fuels that are an option to gasoline and diesel. Today’s standard gasoline, mandated by the federal government, is E10. That is 10 percent ethanol mixed with 90 percent unleaded gasoline. Ethanol is a renewable source of energy, made most efficiently from corn. E10 was developed to reduce the country’s dependence on foreign oil. Proposed for the near-future is E15, with a higher concentration of ethanol.
Ethanol is corrosive and can harm fuel system components on non-E85 FlexFuel capable vehicles. E85 is 85 percent ethanol and 15 percent gasoline. FlexFuel-capable vehicles are designed to operate on higher concentrations of ethanol such as E85. Fuel pumps, hoses, fittings and injectors are larger and are constructed to handle the increased flow rates required of E85 and to resist corrosion.
A downside to the green-appearing E85 is that E85 has about 75 percent of the energy product of gasoline. It may be priced lower per gallon, but the mileage on E85 will also be lower. So, E85 needs to be priced low enough to offset the fuel mileage loss. It seldom is.
Liquefied Petroleum Gas (LPG), commonly called propane, is a pressurized liquid and is a byproduct of refining petroleum or natural gas production and has about 73 percent the energy of gasoline. Compressed Natural Gas (CNG) and Liquefied Natural Gas (LNG) are clean-burning fuels. CNG and LNG develop the equivalent amount of energy as gasoline. CNG, especially, is a very clean burning, very low emission, and very economical option to gasoline. The fuel costs are about 4 percent less than gasoline, and the payback periods are well within the service life of the vehicle.
There are downsides, of course. These fuels must be stored in large, thick pressurized tanks, which takes up valuable cargo space. The crash worthiness simply must be achieved at the OE level—no aftermarket CNG conversion business does FMVSS crash testing. CNG burns hotter than gasoline, so the engine getting CNG fuel must have hardened valves and valve seats. No aftermarket conversion business upgrades engine valves. Finally, infrastructure again, and that means a centralized fueling location, or knowledge of one somewhere in the patrol area.
Engineers have been speculating for many years about using hydrogen to power vehicles. Hydrogen has a lot of positive aspects of an ideal fuel since it is both clean-burning and renewable. To the point, hydrogen is used to make electricity to power an electric motor in the vehicle. So, think of it as ‘hydrogen electric.’ Police fleet managers, who are a part of the GM Law Enforcement Product Council, got the opportunity to drive a prototype hydrogen-powered crossover. It felt like any other total-electric vehicle.
Hydrogen is placed in a carbon-fiber fuel tank. Outside air comes from the front grille to the fuel cell stack. The hydrogen travels from the fuel tank to the fuel cell stack where it undergoes a chemical reaction with the oxygen in the incoming air. This creates electricity, which powers the car. Pressing on the accelerator pedal sends the electricity from the fuel stack to the electric motor, propelling the car. The only byproduct of this process is water, which leaves via the tailpipe. Hey, it’s the future!