Lawnmowers have basically two different types of cutting technology; cylinder mowers and rotary mowers and if you choose a cylinder mower you can opt for push or powered.
Cylinder mowers: Cylinder lawnmowers have a revolving cylinder consisting of sharpened blades set at offset angles which rotate to cut the grass when the mower is pushed or powered forward. The rotating blades form one part of the cutting action, the other is a fixed bar, usually called a bed knife, which is set parallel to the ground. As the mower is moved forward the rotating blades of the cylinder slide against the bed knife cutting the grass in a scissor action. The distance between the cylinder and the bed knife can be adjusted to set the cutting height.
As a result of their scissor action cylinder mowers are able to cut lawns more cleanly than rotary mowers, and can therefore also cut them shorter without damaging the grass. The clippings from a cylinder mower are 
generally finer than those from a rotary mower, so if you mow your lawn regularly you can leave them as mulch. The finest clippings are those from mulching mowers.
Cylinder mowers do however have their limitations and are usually not considered suitable in the following circumstances:
Lawns over 1/4 acre - most domestic cylinder mowers are push rather than powered so lawns over about 1/4 of an acre will take significant time to mow
Very bumpy lawns or lawns with protruding root systems or stones
Very long grass (infrequently cut lawns) or overgrown with tall weeds or dandelions
* correctly adjusted blades are very important for successful use of a cylinder mower
Push Mowers: The most environmentally friendly way of mowing your lawn is to use a non-powered machine, although more effort they produce no CO2 and don’t emit noise pollution. Cheap, easy to maintain and suitable for smaller lawns they are the perfect solution for someone with easily maintainable lawns. Cylinder or reel mowers actually do a better job of cutting grass, their “scissor like” action cleanly cuts the grass blades as opposed to rotary blades which can lead to “browning” of the cut area. Machines such as the Brill Razorcut 38 feature contact-less blades – increasing blade life dramatically, and sealed bearings – all helping to keep the cost of maintenance down. It is worth noting that reel mowers are not suitable for areas with bumps or debris on the lawn, whether the mower is powered or not.
Rotary Mowers: Rotary mowers are always powered and use a petrol engine or electric motor mounted on the top of the blade housing, usually referred to as the deck.
Powered mowers are now seen as the norm. in the UK with a variety of different power sources available, electric machines come in both mains and battery forms while engined machines are either 2 or 4 stroke.
Low emission 4-stroke Petrol engines: Whilst obviously not the most environmentally friendly choice for cutting your 
lawn there are circumstances where a the power and durability of a petrol engined mower remains the only truly viable solution. Fortunately with the advent of lower emissions 4-stroke engines from manufacturers like Honda and Kawasaki, you can still make a more environmentally friendly choice and save money as a result of the reduced fuel consumption.
Electric lawnmowers can be either rotary or cylinder although cylinder machines tend to be more complex and therefore more expensive, however they are more energy efficient and offer a better cut of the grass. Rotary machines rely upon a spinning blade held horizontally above the ground, the sharpened edge and movements of the blade therefore “skim” the top of the grass and cut to the required level. Cylinder mowers rely upon a number of blades attached to a rotating axle, the blades pass very close to another fixed blade beneath the actual “cylinder”. The point where the two meet acts like a pair of scissors to cut the top of the grass. Mains powered mowers are limited by the cord length so are unsuitable for large areas or lawns removed from an electricity supply. A battery powered machine offers a more flexible alternative however they are limited by the power capacity of the battery ands its battery life. There are three types of batteries used in lawn mowers: Lithium-ion, Lead Acid and Nickel Cadmium.
Rechargeable Mowers: Use rechargeable battery techonology and you can choose between
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Lithium-Ion batteries are common because of the unique advantages they offer over other older technologies. They are easy to produce in a variety of shapes so can be used to effectively fill the space available and offer weight advantages of the other two types. They also have a low rate of self discharge, the amount of energy lost when not in use which means long periods of non-use are unlikely to require a recharge. However they are known to suffer from short service lives as over time they suffer from falls in capacity until they become unsuitable for their intended use. They also are less stable than the other two and require protection features not found in other battery types to make them safe for consumer purchase. Environmentally they offer advantages over, both Lead Acid and Nickel Cadmium because they contain no hazardous material.
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Lead acid batteries are most commonly used for car batteries because they can deliver the high current needed, however their use in lower requirement applications I limited because of their drawbacks. They offer low weight to energy ratios and suffer from being heavy and bulky, however they are inexpensive and simple to manufacture, they offer the best cost per watt hours ratio. The environmental impact of this type of battery has limited modern uses of this technology although it is estimated that the up to 90% of these batteries are recycled (URL: http://www.mpoweruk.com/recycling.htm), making it one of the worlds most recycled products.
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Nickel cadmium technology is often used as a replacement for the traditional alkaline AA and AAA batteries because of the ability to recharge and reuse them. Although more expensive and difficult to manufacture they offer a much more environmentally conscious option than disposable batteries. Although their use in larger applications such as cars is limited they were popular for battery operated lawn mowers because of their combination of price and high storage capacity – useful for long operating times. In terms of recycling and the environmental impact of these batteries, they have a long estimated life time and are more tolerant of general “wear and tear” – making them ideal for use in lawn mowers however once they do need to be replaced the toxic chemicals inside need to be recycled properly. Since 2006 the EU has banned the use of Cadmium in electrical and electronic equipment products – thereby banning the use of Nickel Cadmium batteries in lawn mowers.
Innovations in artificial intelligence has made possible the use of robotic lawn mowers, although expensive compared to 
their traditional counterparts they offer both an environmentally friendly option and an easier way of managing your lawn. Depending on the model the positioning system used may vary, the most common involving a border wire while more expensive models can rely solely upon sensors. Entry level models such as the Mowbot 100BP boast smaller operating times and fewer additional features but are able to cover up to 400m2 of grass. Top end products such as the Mowbot 300BL4 offer features such as the “SmartSpiral” function, Bluetooth™ connectivity and up to 5000m2 of cutting area. The whole range of Mowbot robotic lawnmowers offer the ability to “mulch” and more information about mulching can be found below. All robotic currently rely on rotary blades and although they offer a smaller cutting width than a ride on or push mower they require minimal owner input and are nearly fully autonomous.
Mulching – Mulching is the process of finely cutting then re-cutting the lawn clippings created when grass is mown. Mulching machines are available in many ride-on and push rotary varieties and offer environmental as well as time saving benefits. Mulching is achieved by either having a second dedicated blade or changes to the design of the primary blade or airflow system within the deck, this allows the grass clippings to be cut multiple times and helps conceal the cuttings within the existing grass. The cuttings will decompose over time and provide the lawn with nutrients, aiding the growth of the lawn. Mulching is estimated to reduce the time required to cut your lawn by up to 30%. For more follow this LINK to asite all about mulching