The idea of alternative energy at home is gaining popularity as people look for more ways that they can make a positive contribution to the environment.

Unsurprisingly, most energy providers now cater to this demand with a variety of so called 'green' tariffs. However, the term 'green' can cause confusion and there are many different levels of green energy which you should take into account when making your green gas suppliers comparison.

At the most basic level, energy companies will not necessarily guarantee that gas comes from a green or sustainable source. However, they will make a contribution to an environmentally friendly scheme such as renewables or a carbon off-setting.

True green gas

Other energy companies provide genuinely sustainable energy that comes from gas sources which truly are renewable and environmentally friendly, such as biogas. Formed from a process known as anaerobic digestion which converts plant material (biomas) into useful materials, biogas is becoming increasingly popular and the number of AD plants is growing by the year.

As well as the big companies there is a growing number of smaller alternative energy suppliers dedicated to providing renewable power solutions. These are popular with people who want to make sure they receive gas from a renewable source through a company which is genuinely committed to delivering sustainable energy.

How do I compare green gas companies?

In order to combat confusion, Ofgem launched a certification scheme in 2010 called green energy certification. In order to qualify a company must either donate money to charities or trust funds investing in greener energy, support schemes that have environmental benefits, run schemes that have a positive impact on carbon footprints like loft insulation, or contribute to carbon offsetting.

The easy criticism of this scheme is that it can further muddy the water.

Consumers may see this green certificate and assume they are getting more than is actually being delivered. The only way to be certain, then, is to carry out your own green gas comparison.

Is it more expensive?

Unfortunately, because of the cost involved in sourcing and transporting green gas, or contributing to environmentally friendly schemes, green gas energy is likely to be more expensive.

However, if you're keen to help the environment, you may be willing to meet this cost. You can also reduce the price by making a comprehensive search of all the options available and looking at how they can fit into your energy usage.

The number of alternative energy companies is also on the rise, so there is every chance prices will come down in time.