Natural gas as a ‘bridge’. Dangerous procrastination?

by Lindsay Wilson in Discussion

Natural gas as a bridge fuel

There has been much talk of natural gas as a ‘bridge’ fuel lately, particularly due to its role in cutting US carbon emissions.

From an economic or energy security point of view this might make some sense, but in terms of climate change natural gas is a half measure that risks dangerous procrastination.

If all the coal fired power stations in the world switched to natural gas tomorrow we wouldn’t go close to stabilizing atmospheric carbon dioxide concentrations.

Some simple carbon maths shows why we need to be more ambitious.

Carbon Emission Sources

Fossil fuels have done wonders for economic development ever since the start of the industrial revolution.  But if we want to keep on developing without toasting the planet we need to change how we get our energy.

For me, the easiest way to understand our carbon dioxide problem is to think of it in terms of ‘sources’ and ‘sinks’.

The main sources of man made carbon emissions are oil, coal, natural gas and land use change emissions.  Whilst the main sinks for carbon emissions are the ocean, the land and the atmosphere.

In the last 50 years the amount of carbon dioxide mankind has emitted has grown dramatically, due to rising fossil fuel emissions.

Global carbon emission sources

Man made carbon emissions have grown by 150% since 1960.

The majority of this growth has come from oil, coal and natural gas with a smaller contribution from cement production and gas flaring.  Land-use change emissions are down over the last decade because the net flux between deforestation and reforestation is slowly improving.

Carbon Emission Sinks

Once carbon dioxide goes into the atmosphere it stays there for a long time. About 33% is still there after 100 years, and 20% is still in the atmosphere after 1000 years.

But when we think about where our emissions go it is simpler to look at the net change that occurs to the sinks each year.  In this way global carbon emissions are balanced by the annual absorption of the ocean, land and atmospheric sinks.

The following chart shows where our human carbon emissions have gone over the last 50 years.

Carbon Emissions Sinks

The oceans have absorbed 29% of man made carbon emissions since 1960. Land sinks including vegetation, soils and humus have absorbed 27%.  Whilst 44% of carbon emissions have resulted in the growth of atmospheric carbon dioxide concentrations.

The light blue section of this chart is equivalent to the share of annual carbon emissions that ends up in the atmosphere.  For each 7.8 Gt CO2 that remains in the atmosphere the atmospheric concentration of carbon dioxide rises by 1 ppm (parts per million). Between 2000 and 2009 we added an average of 15 Gt COto the atmosphere each year resulting in atmospheric carbon dioxide concentrations rising by an average of 2 ppm each year.  The growth rate last decade was higher than in any earlier decade.

Between 1960 and 2010 growing carbon emissions have caused atmospheric concentrations of carbon dioxide to grow from 317 ppm to 389 ppm.  If it wasn’t for the ocean and land sinks absorbing more carbon dioxide with both rising concentrations and rising emission rates we would already be pushing 500 ppm.

To stop the growth in the atmospheric carbon dioxide concentrations human carbon emissions would need to balanced by the sink capacity growth in the land and oceans.  To slow the acidification of the oceans we would need to do much more.

The Scale of Our Problem

Stabilizing atmospheric concentrations of carbon dioxide is the central challenge of climate change.

We also need action on other positive forcing agents like methane, nitrous oxide, ozone and black carbon, as well as further study of aerosol and cloud management, but without tackling carbon dioxide we cannot properly address climate change.

Although the most common way to highlight the scale of this challenge is as a carbon budget between now and 2050, I find it much easier to understand by just thinking about one year.  That way I’m not thinking about 2050, I’m thinking about what needs to happen today.

I’ll use 2010 as an example.

Stabilizing Atmospheric Carbon Dioxide

Based on global sources of carbon dioxide in 2010 and the average sink absorption over the last decade we would need to cut global emissions in half to stabilize atmospheric carbon dioxide concentrations.  But in fact sinks absorption is also a function of emission rates, so this immediate cut in half would need to be quickly followed by more rapid emissions reductions to maintain stable concentrations.  If technically possible we could also stabilize concentrations by doubling the rate at which carbon dioxide is absorbed by the oceans, land or possibly by some type of technology.  But that technology is not really in existence.

In terms of cutting emissions a 53% reduction in 2010 emissions is equal to almost 20 Gt.  This equivalent to all land-use emissions, all electricity generation emissions and most building emissions put together.

For some perspective, global emissions from coal fired electricity generation were about 9 Gt  CO2 in 2010.  If every coal fired power station in the world switched to natural gas tomorrow it would cut 5 Gt of CO2 from our emissions at most.  That would be impressive, but it is just a quarter of what is needed to stabilize atmospheric COin the very short term, and nothing like what is needed in the long run.  In fact given the expect rise in power generation global these cuts would be all but cancelled by demand growth.  Moreover, if you also consider methane and particulates in your calculations the ‘benefits’ of switching to gas evaporate even further.  In reality we need to be cutting carbon at 4% per annum while growing energy supply.

If the world is remotely serious about stabilizing atmospheric carbon concentrations while meeting the growing demand for energy in developing economies there is no time for fossil fuel ‘bridges’, unless they include carbon capture and storage.  If no one can make carbon capture and storage work then we need to gradually marginalize fossil fuel use to producing things like steel, cement, plastics and fertilizer and moving them in ships, trucks and planes.

Most forecasts expect global energy demand to grow by 50-100% between now and 2050, as poorer nations develop and the global population grows.  At the same time research highlights the risks of land and ocean sinks becoming less efficient over time. In the worst case scenarios sinks could actually become net sources of emissions in the future due to feedbacks like forest fire, drying peatlands, melting permafrost  and out-gassing from the oceans.

To have any chance of doubling energy use, cutting carbon emissions and improving natural sinks we need every low carbon policy, technology and action available.

The Whole Kitchen & Sink

At present there is no single technology or policy capable of dealing with the carbon problem by itself.  We need to work with everything that we have as well as invest in creating new low carbon tools.

An incomplete menu of our options looks something like this:

  • Carbon pricing – carbon taxes, cap and trade, subsidies
  • Efficiency standards – buildings, vehicles, appliances and gadgets
  • Low carbon power – wind, solar, nuclear, hydro, biomass, geothermal
  • Carbon capture and storage – new build, retrofit, air capture
  • Innovation – power storage, biofuels, materials, vehicles . .
  • Planning – low carbon cities, architecture and design
  • Sinks – deforestation, afforestation, biochar, conservation tillage

Rather than competing many of these ideas actually reinforce one another.

A stable carbon price, for example, would improve the incentives for all manner of technology deployment and innovation.  Efficiency standards can achieve mitigation in sectors that aren’t price sensitive.  And the improvement of land sinks could provide enormous mitigation at relatively low cost while we build new energy infrastructure.

And that is just carbon.  We also need a similar urgency to mitigate black carbon, methane, nitrous oxide and ozone as well as to study if the potential benefits of using the oceans, aerosols or clouds to cool the planet in the future will outweigh the risks.

Whatever the best mix of solutions is one thing is clear, the only fossil fuel ‘bridge’ we can afford to build is carbon capture and storage.  Natural gas might be preferable to coal and oil, and be a natural back-up to wind and solar in the power sector, but it just isn’t good enough given the global carbon constraints.

Given that 87% of global energy supply in 2010 came from coal, oil and natural gas that may sound naive, but the alternative is untenable.  We simply can’t afford to build ‘bridges’ from coal, to tar sands, to shale gas, to methane clathrates.

Our carbon problem requires far greater ambition.

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    • wideEyedPupil

      Very charitable of you not to consider all the papers pointing to fact that if fugitive emissions are calculated not on industry estimates (which our govts take on good faith) but using recent field measurements at exploration drill heads, transmission lines and distribution networks and more modern accounting methods using a 85x CO2 for methane over 30yr timeframe then the supposed climate advantages of gas evaporate and it actually is worse than burning coal for energy, especially in less efficient peaking power plants.

      • Lindsay Wilson

        I’m very clear about what I do and don’t include. As I noted in the statement ‘Moreover, if you also consider methane and particulates in your calculations the ‘benefits’ of switching to gas evaporate even further.’

        As for timeframes it is not more ‘modern’ to consider different time frames for global warming potential. Moreover for almost a decade beginning in 1998 radiative forcing associated with methane was stagnent, meaning it had no warming effect beyond adding to CO2 as it broke down. There is not a ‘correct’ time frame for GWP, I’m simply using the convention of 100 years

        • wideEyedPupil

          By modern accounting I mean not saying fugitives emissions are 0.55% of total gas production just because industry says so.

          “Moreover for almost a decade beginning in 1998 radiative forcing associated with methane was stagnent, meaning it had no warming effect beyond adding to CO2 as it broke down.”

          Are you serious?!

          I’m not saying one time frame is more correct than another, just more appropriate. If I eat five vegemite sandwiches a decade and you want a number to indicate my personal sandwich consumption you could say I ate five per decade, ten for every twenty years or if I live to be 70yo 35 per thousand years or 35 per 10^52 years. Which figure is more appropriate? I’d argue for the decade consumption figure. Same way I’d argue for twenty year time span for a gas that lives about 12 years in the atmosphere before it breaks down to CO2.

          “the ‘benefits’ of switching to gas evaporate even further”

          Why the vague negative benefits language? I’d just come out and say the so-called ‘benefits’ of gas are illusory. Fugitives knock over the ‘half as bad as burring coal for CO2 production’ argument. Then there’s all the environmental damage that fracking causes the environment and long term damage to aquifers (tens of thousands of years). Many papers point to that.

          Plus when considering the expense of a new energy infrastructure around fracked gas and the export potential which will drive retail prices higher (long term domestic wholesale contracts already have priced up by factor of 3x in Australia since export terminal construction started in 2009).

          • Lindsay Wilson

            Does the post above look vague? Of course I’m not interested in natural gas as a ‘solution’.

            • wideEyedPupil

              That’s great, Lindsay. I guess I just find your arguments opposing fossil-gas a little less forceful than I’d wish for!

              We are facing what may be a vast expansion of the CSG and shale-gas industry on much of Australia’s arable land and many politicians and cronies of this industry point to ‘clean fuel’ arguments and I for one am all for knocking them on the head, without even resorting to global emissions reductions timetables for evidence.

              Potsdam Institute says Aust. and USA must reduce to zero emissions in this very decade if you use historical emissions to weight on national reduction pathways to get to the 2ºC guardrail (so called).

              Also your advocacy for CCS in your conclusion (unsupported by the main body of article) I frankly find more than a little perplexing. It’s not the first time I’ve come across advocacy for CCS in the Climate movement, perhaps we can leave that discussion for another day and another interesting blog article and just agree to disagree (strongly!) until then.

              Incidentally those researchers I’ve spoken to close to those in this area of research say as nutty as the commercial case for CCS is, its the gas industry that will be reaching out for it not coal since they are closer to a break even point than coal regards emissions (if they could control fugitives).

            • Lindsay Wilson

              Dude, I am no advocate of CCS! I actually don’t believe the economics or engineering stack up without an astronomical carbon price. But you can’t deny it would be hugely useful. It is the only way to decarbonize many industrial emissions (steel etc) and would offer the promise of carbon negative electricity with biomass. It should be pursued, but sadly the only people with the power to do it are the oil and gas industry, and they seem to think of it as PR. Will get back to you on email, Lindsay

            • wideEyedPupil

              Would be hugely useful but so would cold fusion at half the price of onshore wind power! Have you read about electric steel production without the carbon emissions? It might even end up cheaper to produce than conventional steel.

              Industrial processes are only just starting to look for cradle to cradle solutions and I think decarbonising is possible for many processes without CCS but if they can do it without the huge energy demand so far required great.

            • Lindsay Wilson

              Almost half the world coal fired generation capacity has been installed since 2000. They will run for 40 years. CCS retrofit would be a god send, just like fusion or dirt cheap solar and storage, or anything else that works. I really don’t give a monkeys. I’m technology agnostic

    • wideEyedPupil

      I would also question the land use change figure. Land use patterns is the number you want, because it’s not all just changes it patterns. Enteric fermentation accounts for a large part of land use patterns in Australian agriculture which BZE and MSSI estimates are 55% of national total emissions when using that 20 year time frame (not one hundred year timeframe). Twenty years is significant given irreversible Climate tipping points we may well reach within the next twenty years.

      Also land use changes like the regular re-burning of savannah to promote grasses over open woodland and woody weeds for grazing is not accounted for in National Green House accounting. You could argue either way about whether it’s land use change or same use continued but it’s definitely a major source of CO2 and black carbon (black carbon is now listed by IPCC AR 5, 2013 as a GHG) in our national emissions profile.

      • Lindsay Wilson

        Have you looked at the figures for global land use emissions? I’m not saying we are winning the battle per se but it is one area of hope. Black carbon is important, but often balanced by the cooling effect of co emitted organic carbon when discussing biomass. Not so with diesel.

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