Hybrid vehicle made urban transport system more fuel efficient with less pollution:

Hybrid vehicle made urban transport system more fuel efficient with less pollution:

At present the road transport sector is the most polluting of all. It is generating more carbon dioxide (CO2) than electricity generation or the destruction of the rainforests. There are more than 600 million cars in the world today. In developed countries this number is set to double by 2015; and elsewhere in developing countries like China and India the increase will be even faster. Although the efficiency of operation of car engines manufactured has been substantially improved by incorporating better ignition management systems and the use of improved diesel engines; the tendency is still to build vehicles with performances much higher than the road conditions allow. Growth of population in developing countries resulted in congestion and pollution which is beginning to lead to a move towards electrical traction and an expansion of public transport systems, although people try to stick to the fictional “freedom” conferred by the private car.

In this context, development of fuel-cell-powered cars running on hydrogen fuel are quite encouraging, as are hybrid vehicles that use a small, optimized gasoline or diesel engine to charge a battery. Both the systems have demonstrated a good range and able to reduce pollution quite substantially.

A. As we discussed earlier some relevant aspects of hydrogen fuel-cell vehicle; we would now discuss about few points on hybrid system of vehicles as Hybrid vehicles are taking the auto world by storm. Ever since some of the Japanese auto manufactures (Toyota and Honda) introduced their hybrid vehicles into the marketplace, the demand has exceeded the supply. Most of those who have been attracted to the new lines of hybrid vehicles do so out of regard for the environment followed by a desire to lessen this country's dependence upon foreign oil and save a few bucks on high gasoline prices.

B. A hybrid vehicle is a vehicle that uses two or more distinct power sources to propel the vehicle. Common power sources that hybrid vehicles are known today are ‘on-board rechargeable energy storage system (RESS) and a fueled power source either by internal combustion engine or by a fuel-cell’. Hybrid vehicle in general achieves greater fuel economy with lower emissions than conventional internal combustion engine vehicles. These favorable economic factors along with cleaner systems are primarily achieved by four elements of a typical hybrid design; such as, (a) Recapturing energy normally wasted during braking etc.; (b) Having significant battery storage capacity to store and reuse recaptured energy; (c) Shutting down the gasoline or diesel engine during traffic stops or while coasting or other idle periods; (d) Relying on both the gasoline (or diesel engine) and the electric motors for peak power needs, resulting in a smaller gasoline or diesel engine sized more for average usage rather than peak power usage.

These are the essential features that a hybrid vehicle has, which make it efficient in respect of fuel economy and providing emission-free environment for city traffic where there are frequent stops, coasting and idling periods. In addition, noise emissions are greatly reduced, particularly at idling and low operating speeds, in comparison to conventional gasoline or diesel powered engine vehicles. It may be important to mention here that, for continuous high speed highway use these features are much less useful in reducing emissions.

C. Another important aspect in hybrid vehicle is use of efficient battery. With the advent of new technology, more efficient batteries are made, which has made a hybrid vehicle more reliable. Today most hybrid vehicle use batteries that are made of nickel and lithium ion; these are regarded as more environmentally friendly than lead-based batteries used for most of cars today. Many of the manufactures claim that, even after use of hybrid car for about five years, no battery has been replaced. Hybrid technology for buses has seen increased attention since recent battery developments decreased battery weight significantly.

D. In short, the most advantageous factors in use of hybrid vehicles in city condition are:

(a) Improving fuel economy by (i) reducing wasted energy during idle/low output; (ii) recapturing waste energy (i.e. regenerative braking); (iii) reducing the size and power of the petrol / diesel engine, hence inefficiencies from under-utilization, by using the added power from the electric motor to compensate for the loss in peak power output from the smaller petrol / diesel engine.

(b) Durability and reliability of road transport is improved by (i) reduced wear on the gasoline engine, particularly from idling with no load; (ii) reduced wear on brakes from the regenerative braking system use; (iii) there's no definitive word on replacement costs of the batteries because they are almost never replaced.

(c) The environmental impact of hybrid vehicles has been observed more favorable than any petrol / diesel engine vehicles. (i) Reduced noise emissions resulting from substantial use of the electric motor at idling and low speeds, leading to roadway noise reduction, in comparison to conventional gasoline or diesel powered engine vehicles, resulting in beneficial noise health effects. (ii) Reduced air pollution emissions due to lower fuel consumption, leading to improved human health with regard to respiratory and other illness. Pollution reduction in urban environments may be particularly significant due to elimination of idle-at-rest.

E. Now several transport system uses hybrid technology: such as (a) Motorcycles (b) Automobiles and light trucks, currently number of manufactures in US, Japan and European countries produce hybrid electric automobiles and light trucks (c) Buses (d) Trucks (e) Military vehicles (f) Locomotives (g) Marine and other aquatic purposes.

Noise barriers are to mitigate highway noise pollution:

Noise barriers are to mitigate highway noise pollution:

High level noise is a disturbance to the human environment. Because of urbanization, noise in all areas in a city has increased considerably. One of the most pervasive sources of noise in our environment today is those associated with transportation. People reside adjacent to highways, are subjected to high level of noise produced by trucks and vehicles pass on the highways. Prolonged exposure to high level of noise is very much harmful to the health of mankind.

Artificial noise barriers are solid obstructions built between the highway and the residential areas along a highway. They block major portion of noise produced by passing vehicles on a highway. Effective noise barriers typically reduce noise levels by as much as half or more. The construction of noise barrier may be built in the form of earth mounds, vertical wall along the highways for creation of blockage of sound generated by heavy vehicles. The effectiveness of mitigation of sound depends upon the height of the mounds or walls. Function of noise barriers are: (1) it can reduce the loudness of traffic noise by as much as half; (2) It may not completely block all traffic noise, but gives certain relief to the residents; (3) It may be effective, regardless of the material used; (4) It must be tall and long with no openings for making it more effective; (5) It must be designed to be visually appealing looking into the aesthetic value of the site.

Apart from constructing artificial noise barriers, creation of greenbelt, by plantation of trees along the highways. The space between the residences and highways may be utilized for creation of greenbelt. As more and more noise pollution problem is being cropped-up, city planners are increasingly adopting various methods to

Example of plantation done in mined out site – A case study

Example of plantation done in mined out site – A case study

A site at Southern India – running opencast lignite mines (more than 20 million tones of annual capacity) cum coal-fired power plants (capacity about 2500MW). The mines used to generate huge quantity of overburden apart from generating fly-ash from coal-fired power plant. One of the major challenges it has to develop rich cover of green belt.

In fact, excavating more than 20 million tones of lignite annually involves a removal of about 135 million cubic meters of overburden. The overburden excavated is backfilled in mined out areas and the modified slope as per stability, by conventional mining equipments. The dumped overburden is devoid of any nutrients to support plant growth. Adopting indigenously developed techniques, selecting locally available species of plants as per the local climate and establishing organic farming in order to enrich the wastelands created by dumps. While selecting the plant, species of dense foliage have been used for plantation. One of the criteria for selecting the plants was of high growth nature. Planting about 4000 different varieties of plants including fruit bearing trees, herbal cultivation has been undertaken in the reclaimed area. The herbal cultivation is to cater to the needs of the local ayurvedic dispensary.

Advantages:

(a) Dense foliage of green belt created around the mines serves as a barrier, to prevent dust penetration from operation of heavy earth moving machineries and movement of off-the-road vehicles in the mines into nearby dwelling is negligible;

(b) the noise pollution from these sources has been checked quite substantially, because of creation of this green cover. It has been observed that noise level reduces by 10 decibels per every 10m wide green belt development;

(c) Trees reduce mean temperature of the area by 2 degree Celsius;

(d) Trees in an acre of land have the potential to absorb six tones of sulphur dioxide, thus reducing air pollution.