Rain Water Harvesting - an imminent necessity

My mother remembers being able to feel the water in a well by just lowering her arm into it. This was the situation decades back in a water-well in my cousins’ place, right beside our house in Cuttack. Today, the well has water a few feet below; this being in a city surrounded by two rivers. Ground water depletion is not alien if you are living in bigger cities like Chennai, Bangalore, Delhi, etc. In Bangalore, 800-1000 feet depth is the norm of new bore wells in most areas. 20 years back, a 150 feet bore well was sufficient to get water in that area. Rampant usage and removal of rain water harvesting sites like lakes and ponds are the causes of this. Ponds being replaced with high rises are a common sight in every developing city. 

more than 200 days of free swach water considering Kejriwal’s 700 litre per day use. Imagine the amount of rainwater wasted every year.

What is ground water? 

Ground water is the rain water percolated in the earth’s porous surface. Consider the surface below us a huge water storage. The top soil layers (sand, silt, gravel) are porous. Rain water gets absorbed through these and moves down by gravity till it reaches an impermeable surface rock or cracks in such rocks. The rain water saturated in this region can be extracted for use by drilling a well. These water bearing rocks or unconsolidated materials (sand, silt, gravel) are referred to as an aquifer. The depth at which aquifers are found depends on the geology of the place and amount of rainfall it receives. In rocky high altitude Bangalore, the water table lies much lower than the riverbed city of Cuttack where bore wells of 100 feet can suffice. Bhubaneswar, the twin city of Cuttack, has a lower water table too owing to its slightly higher altitude and distance from big rivers. Apart from that, rampant construction has lead to ground water shrinkage in the capital city. New bore wells have average depths of more than 200 feet here. Well it is undeniable that dry aquifers can lead to catastrophic effects on human civilization; storm water off buildings and roads causing flash floods, or dry wells aiding water tanker mafias. 

The percolation pit and recharge well are functionally similar to a soak pit.

What can be done to recharge the ground water? 

Ground water has depleted because rain water has not been allowed to enter the aquifers. In urban areas, there are a few ways to recharge the ground water. One of the simplest ways is rain water harvesting off the surface of buildings instead of letting it run off in the storm water drains. Storing the rain water in underground tanks/sumps or drums is very effective. Rain water is one of the purest sources of water. However, the roof surface must be clean enough to ensure that this water is potable. A simple mesh filter is often enough to use this water for most purposes like cleaning, washing, bathing, etc. This directly reduces your water consumption. Rain water is water filtered to perfection by nature. When this water reaches polluted rivers or streams via storm water drains, it gets contaminated. Pumping and treating this water back to houses is wastage of huge amounts of energy. Soak-pits are another simple way of recharging ground aquifers. A soak-pit is essentially a small dug out pit lined and layered with permeable materials like sand, coal, gravel, etc where rain water is allowed to flow, get absorbed and filter into the aquifers. A small soak-pit of 4x4x4 (feet) dimension can do wonders to increasing your ground water level. Larger the soak-pit, greater is the water absorbed. 

Aquifer

Another important way is recharging your bore well directly with the rain water. This process involves adding filters to the rooftop storm water discharge pipe. Every defunct bore well should be fitted so. Alternatively, one can dig up a soak-pit near the bore well. This would filter the water better and prevent clogging but a lot of water would have to be diverted away as its capacity & filtration rates are low. 

How much water can be collected? 

Rain water collected = Area of catchment (roof) X Total rainfall in a year. For Bhubaneswar, which receives around 1500 mm of rain every year, the rain water that can be collected from 100 square meters roof is 150000 litres. This means more than 200 days of free swach water considering Kejriwal’s 700 litre per day use. Imagine the amount of rainwater wasted every year. 

Rain water harvesting needs to be implemented both on the individual and organizational level. The government needs to introduce laws which mandate rain water harvesting in every building and plot of land. Some states in India have laws for bigger buildings. Apart from that, community and public rain water harvesting projects can be undertaken to improve ground water levels. Soak-pits or recharge pits by the side of roads can immediately reduce chances of flash floods while recharging dried aquifers below. High rise buildings, where consumption is high per unit area, can greatly benefit from rain water to bore-well recharges. According to a recent report, 80% of surface water in India is contaminated. Water is extremely precious; we have to start caring immediately. 

Maruti Suzuki to launch Swift Hybrid - can 48.2 kmpl be real?

Maruti Suzuki is expected to launch the Swift/DZire Hybrid car in India this year. The car is ready and was driven around on World Environment Day (5^th June) in Delhi. This announcement comes after the introduction of FAME (Faster Adoption and Manufacturing of Electric Vehicles) by the NaMo Government. Under this scheme, four wheelers will get incentives ranging from Rs.13,000 to Rs.1.38 lakh from the Government of India. The Swift Hybrid will be a Range Extending Hybrid, that is it will have a 5kWh lithium battery, with a 55 kW(expected) permanent magnet synchronous electric motor and a 658cc, 3-cylinder petrol engine. The net power output will be 73bhp. Maruti claims an impressive fuel economy of 48.2kmpl which we will cover later. This car has an all-electric range of 25.5km. By plugging in to the mains(200 V), this car can be recharged in 90 minutes. The car weighs 1600 kg, which is substantially heavier compared to the petrol (965 kg) and diesel (1060kg) variants. 

The Maruti Suzuki Swift Range Extender Hybrid will have 3 modes - Series Hybrid, Parallel Hybrid and all-electric. In series hybrid mode, the 658 cc petrol engine charges the lithium-ion battery which then powers the electric motor. In parallel hybrid mode, both the petrol engine and the electric motor drive the car. In all-electric mode, it is battery power alone. 

The running cost can be assumed to vary between Rs.1.3 to Rs.4 per km

How efficient will it be?

48.2 kmpl seems like a tall claim and this is probably under ideal conditions(or all-electric mode only). The thing with hybrids is that the cost of running is very different when it runs on battery alone (all-electric mode) and when it runs on petrol mostly(series mode). The parallel mode will deliver an efficiency figure in between the other 2 modes. This engine used is the one powering the new Japanese Alto and Wagon R Kei cars. It is extremely fuel efficient, having a rating of 36kmpl for the Japanese Alto. Mind you, that Alto weighs weighs less than half of this Swift Hybrid. And more the weight, less the fuel efficiency. We assume 48.2 kmpl is the equivalent cost of running in all-electric mode. The 5kWh battery would need slightly more than 5 units of electricity to charge. Considering unit cost of 5 rupees, and the range of 25.5km, the running cost in all-electric mode would be around Rs.1.3/km which corresponds to the 48.2kmpl figure (Rs.67/48.2kmpl = Rs.1.39/km). The fuel efficiency in the series mode, that is after the battery charge from mains has depleted, will determine the real running cost of the car. If the car delivers 18kmpl (half of Alto Kei), then it will be as economical (around Rs.4/km) as a normal small car. Hence the running cost can be assumed to vary between Rs.1.3 to Rs.4 per km. 

Yes, it will definitely be more efficient than a normal small car because of regenerative braking. Regenerative braking is the process of recovering energy that would have otherwise been lost during braking. The electric motor runs as a generator when the accelerator is let off, thereby gradually slowing down the car and charging the batteries. This is extremely useful in busy roads. Regenerative braking also increases the life of brake pads. Thus, the hybrid is extremely efficient in a stop-start traffic situation. A petrol/diesel car wastes a lot of fuel idling. In hybrids, generally there is no idling as the electric motor and battery take care of the drive in choc-a-block traffic conditions. Energy is also recovered during braking. 

How well does it drive? 

The Swift petrol and diesel have been a hoot to drive. How the Maruti Suzuki Swift Range Extender Hybrid will drive is a big question. The extra weight due to the battery and electric motor, is a concern. The battery on the base will aid handling by lowering the center of gravity. Torque figures have not been released, but it is safe to assume that it will be high considering electric motors produce 100% torque from 0 rpm unlike petrol and diesel engines – where it is almost linearly produced. The power to weight ratio is not high, but it would be better to wait for the 0-60 figures to get an idea of its performance. 

Is it worth buying? 

This is difficult to answer as the prices have not been revealed yet. If Maruti were to price this slightly or in the range of the diesel variant, it could be well justified. Though there is the FAME incentive of Rs.1.38 lakhs, a few key components like the motor, battery, etc are going to be imported, and so it could be priced higher. The DZire can be a safer bet considering Maruti has a bigger margin there – around Rs.80k more for 10 kg of metal and a little bit of engineering. Plus the ‘sedan class’ image is a huge draw in India. The Swift Hybrid has the potential to become the 1^st mass market hybrid car in India as the only options currently are the Rs.30 lakhs plus Toyotas, the Prius and the Camry, or the Rs.2.2 crores BMW i8. 

Apart from that, if your everyday driving is around 25 km or there is a provision to charge the car at your office (just a 15A plug point), this could be very ideal for you. Public charging points are getting popular. In some European and American cities, there are more charging points for electric cars than petrol pumps. Mahindra has taken the initiative to introduce charging points in Bangalore at popular parking places like Malls, Coffee Shops, Offices, etc. Battery pack warranty is also a concern. Mahindra gives 5 years while California mandates 8 years on all battery driven vehicles. Hybrids offer the best of both worlds; they are greener than petroleum driven cars, while having no range-anxiety unlike pure electric cars. They weigh a lot more due to both powertrains and this is inefficient, strictly speaking in an engineering point of view. They are not so green if your daily drive is a lot more than their electric range. The future is bigger batteries, offering higher pure electric range (like the Chevy Volt – 60km and BMW i3 – 150 km) and smaller petrol engines just for ‘range extending’. This is until pure electric cars like the Tesla Model S become more affordable or the Nissan Leaf and Mahindra Reva e2o get more range.      

Electric buses - ideal for our cities

BYD K9 electric bus in London

The Bangalore Metropolitan Transport Corporation has recently started trial runs of Electric Buses for its vast public transportation network. Electric Buses are slowly gaining acceptance and have been adopted in few cities around the world. The most popular of these buses is the E9 – manufactured by BYD – a popular Hong Kong based battery and automobile company. Electric buses are commercially in use at various places in China. They are in trial at Utah, Chile, London, South Korea.

The batteries that BYD uses are Lithium Iron Phosphate, developed in-house. These give a range of 250km per charge, which is quite respectable for a day’s intra-city route. They can be charged in 6 hours at normal rate and 3 hours for a quick charge. Ideally electric city buses can be fully charged overnight or given short bursts of high speed charging during terminal stops. Another possibility is wireless induction charging. Read more about that here. It consumes 100 kWh in an hour and that translates to just Rs.4 per km, as compared to Rs.20 per km in diesel buses. The battery is expected to last 6000 recharging cycles or 1.5 million kms, thereby capable of saving nearly a crore of rupees before a battery swap. This is considering the fact that there are hardly any maintenance costs in electric vehicles. Unlike petroleum operated vehicles, they do not have filters, oil changes, turbochargers, etc. These expenses are a lot in heavy vehicles like buses, and the time taken to service also accounts for revenue loss. In fact there is only one moving part in the electric motor.   

Electric buses are an ideal choice for cities with dense traffic and otherwise too. They are very silent. A V8 roar may be appreciable in a sports car, but an old bus noisily accelerating and blowing soot on your face is never charming.  Apart from that, electric buses have regenerative braking. This is a technology that helps vehicles recover the kinetic energy of motion that is otherwise lost during braking. What happens is when the foot is left off the accelerator, the motor acts in reverse as a generator using the motion to top up the excess energy into the batteries. This also reduces the need of brakes in predictable situations (Bus routes = more predictable), thereby elongating the life of brake pads and shoes by a huge margin. This technique is very useful in stop-start situations which are very high in dense city traffic. Going downhill, a Mahindra Reva e2o (an electric car from India) has been able to recover 20% more range on the return journey on a particular trip to hilly region.  

Then there is the usual electric advantage of not wasting fuel at traffic stops – they use energy when the accelerator is pressed. Hence there is no wastage of energy like internal combustion engines which have to kept on during idling and consume fuel in that process. This is particularly beneficial in dense cities and typically for buses as they stop for loading and unloading of people. This frequent dis-acceleration also helps in regenerative braking. Also electric motors produce 100% torque at 0 rpm. This high torque nature is more suited to heavy vehicles like buses and trucks.

With rising costs of polluting petroleum, the operating cost difference will widen further for sure. Electric buses at present scenario are able to recover the initial investment fast too. A proper charging infrastructure is highly necessary. The grid needs to get greener. Dirty coal needs to be replaced with renewable sources like hydro, solar and wind energies. Karnataka produces a fair share of green electricity. These low floored, air conditioned electric buses will go head-on with the red Volvo city buses and are expected to be even more comfortable than them. They will also make the Bangalore air more breathable. We hope this model is a success and it is replicated in more cities throughout the country.