What is the difference between renewable and sustainable?

If you come here often, you’ll have heard us talk about sustainability on numerous occasions – how it forms a key part of our purpose, how car sharing can be considered sustainable or how we are always looking to support sustainable businesses individuals and businesses across the UK.

But what does that word ‘sustainable’ really mean? And how does it differ from ‘renewable’, especially when we are talking about energy?

The two words are often used interchangeably but are actually two very different concepts. Renewable literally means ‘to make new again’ so pertains exclusively to resources that can naturally be renewed over time and do not have a fixed quantity or end point. When talking about renewable energy, this includes solar power, wind power, hydropower, geothermal power, tidal power and biomass power. Because sunlight is abundant and freely available, it is considered renewable. The same goes for wind or tides: they are natural processes that occur naturally and frequently and as such are renewable resources from which we can harness energy.

Something is considered nonrenewable when it can run out or takes too long to replenish. Fossil fuels, for example, are non-renewable because they cannot be replicated within a human lifetime. While they are continually formed by the breakdown of living organisms, like plants and animals, it takes millions of years to turn into fuel, so they are being used much faster than they can be replenished – thus rendering them nonrenewable.

However, not all renewable resources are necessarily sustainable. The word ‘sustainable’ originally just meant that something was able to continue over a period of time, though it has recently taken on a new definition as something that causes little or no damage to the environment and therefore is able to continue for a long time. What that means is that for something to be considered sustainable, it has to be able to be maintained for the foreseeable future without causing damage. Sunlight, a renewable resource, is sustainable because it cannot be used up, run out or become unusable. Our use of sunlight as an energy source does not affect or damage the sun itself. It will continue to shine no matter how we use it. Biomass, on the other hand, including wood from trees, which is considered renewable because trees will keep growing, can be made unsustainable through our excessive use of it as an energy source.

The relationship between renewable and sustainable therefore comes down to two things: speed and damage. If the renewal rate of a resource is too slow (i.e. trees and crops growing) and we end up using more than can be created, it will become unsustainable. Equally, if the use of a renewable energy source causes damage to the environment, like geothermal energy’s release of CO2 for example, it may also be considered unsustainable.

At Karshare, we recognise that the use of petrol and diesel vehicles can not continue into the future because it is too damaging to the environment. Driving a car is fundamentally an unsustainable practice. Through car sharing, we hope to initiative a move away from car ownership as a necessity. By sharing vehicles between larger groups of people, we can reduce the number of cars on our roads and demonstrate that we can do more with less. Car sharing is not the end goal for our planet. It is simply a way for us to enter into a new chapter – where the future is a bit more sustainable.