Two out of three ain’t bad - is natural gas our best energy source?

Materials World magazine
3 Jul 2011

Secure, cheap and green – the holy trinity of our 21st century demand for energy. Very few sources achieve all three, but natural gas comes close, with half the CO2 emissions associated with coal and almost none of the sulphur. It is very versatile, being used for electricity generation, fuel for heating and cooking, and even as liquified fuel for motor transport. News that hydraulic fraccing on a shale gas project near Blackpool in Lancashire may have been responsible for triggering a minor earth tremor in the same week that Scottish Power announced a 19% increase in its UK domestic gas price seems ironic.

The unconventional reserves associated with shale gas and coal bed methane (CBM) have transformed the North American gas market, and reversed the upward trend in American natural gas prices. According to the BP Energy Review, the shale gas and CBM share of the North American market has risen from almost zero to more than 20% in the last 20 years, and is predicted to rise to 40% by 2030. As a result, the USA has no reliance on imported gas, and supply is considered to be secure.

Western Europe, on the other hand, imports 40%, by pipeline from Russia and other former Soviet Union countries, or shipped by liquified natural gas tanker from the Middle East. How secure is this, given the geopolitical uncertainties in the world today?

As events in Lancashire highlighted, shale gas fraccing is hugely controversial, with reports in the USA of contaminated water supplies, and some countries considering legislation to ban the practice altogether.

So what about the renewable alternatives, and how do they compare to the secure, cheap and green conundrum? The Digest of UK Energy Statistics defines renewables as hydro, wind, wave and tidal, solar and photovoltaics, and biomass. Biomass is the combustion of any organic energy source such as landfill and sewage gas, wood or waste material. As such, it is no greener than natural gas in terms of CO2 emissions.

Hydro power is certainly green, but few, if any, suitable large-scale sites have been developed. Solar and photovoltaics are neither cheap nor particularly suitable to a northern European climate. Wave power is unproven, but given how coastlines have been shaped and battered over the millennia, I am sceptical that manmade devices will fare any better. Conversely, tidal power is as reliable as the waxing and waning of the moon, but at what cost to the flora and fauna that rely on the unique environment that tidal estuaries provide? And finally to wind, where the installed capacity, reliability and other parameters are hotly debated between the proponents and antagonists. A generally accepted load factor – the power generated as a percentage of installed capacity – is about 27%.

So we can have relatively cheap and green conventional natural gas but with a question mark over long-term security; coal that is cheap and secure but at high environmental cost, unless we accept expensive carbon capture and storage; nuclear, which is neither cheap nor green but does provide a reliable base load; or renewables, none of which have proven reliability, most of which are expensive and not all are necessarily green.

Secure, cheap and green – two out of three ain’t bad. The question is, which two?