Clean Power

Published on May 16th, 2016 | by Guest Contributor


Debunking 4 Myths About The Clean Energy Transition, Part 4: Carbon Emissions

May 16th, 2016 by  

This is part 4 of a 4-part series – see also Myth #1: The Duck Curve limits renewables integration, Myth #2: Excess renewables must be curtailed or stored, and Myth #3: Clean energy increases consumer costs via higher rates.

By Robbie Orvis, Michael O’Boyle, and Hallie Kennan of Energy Innovation

America’s electric system is at a stark inflection point: coal power plants are operating at all-time lows with growing retirements, natural gas prices are at historical lows while power generation is rising, electricity sales are flattening, extreme weather events are forcing more resilient infrastructure, and plunging renewable energy prices have made low- or zero-carbon sources cost-competitive with conventional fuel sources.

Rapidly reducing greenhouse gas emissions from the electricity sector is now possible without radically disrupting grid operations, costs, or reliability. But the grid will require a more substantial transformation as we rely on higher shares of variable renewable generation. Some critics argue technological, financial, and institutional barriers will prevent significant decarbonization in the electricity sector, or will drive up the costs at the very least. But four common clean energy myths are easily debunked by facts and experience that show a low-carbon energy future is possible without sacrificing affordable, reliable service.

Myth #4: Natural Gas Generation Is The Main Reason For The Decrease In Carbon Emissions

Reality: Renewable energy and energy efficiency have played major roles in the decline of CO2 emissions

According to Energy Information Administration data, US carbon dioxide emissions peaked in 2007 at 2,425 million metric tons and have remained below that level in the years since.

Because of the coincident rise in power sector natural gas capacity, it’s easy to conclude our transition from dirty coal to less-dirty natural gas is the biggest contributor to this decline. However, significant evidence shows the acceleration of renewable energy and energy efficiency contributed far more than natural gas in reducing carbon emissions.

US power generation 2007-2014

While more natural gas generation (215 terrawatt-hours, or TWh) has been added than non-hydro renewables (approximately 180 TWh) since 2007, renewable generation produces essentially zero emissions, while natural gas still emits roughly half the carbon dioxide that coal does. This means added renewable generation may have twice the impact of natural gas in reducing carbon dioxide emissions when it replaces coal. And that’s only factoring in the downstream emissions from natural gas combustion; when upstream methane leakage is taken into account, natural gas may be just as bad for the climate as coal. Thus, the addition of renewables has had a far greater relative impact in reducing emissions.

Energy efficiency has, perhaps, been an even greater contributor to emissions reductions than either natural gas or renewables. For decades, new appliances, equipment, and building techniques have been enhanced to consume less power while providing the same level or even improved performance. All of this has had a major impact on overall electricity use, which has decreased from 2007 to 2014.

While electricity sales did take a sizeable dip during the Great Recession in 2009 and rebounded after economic recovery in 2010, sales have since turned downward again, despite continued strong economic growth.

Between utility efficiency programs and tightened codes and standards, efficiency efforts have reduced electricity demand by about 200 TWh, and are estimated to have contributed at least a third, if not more, of total emissions reductions to date.

US electricity sales

Pulling It All Together

Accurately estimating the cost of electricity sector decarbonization is undoubtedly a difficult endeavor because of rapid cost declines, myriad technologies, market operations, and other nuances. Institutional inertia favoring an outdated system further clouds this picture.

Nevertheless, it is increasingly clear that today’s available technologies and options can successfully decarbonize the electric sector. In order to cost-effectively achieve the goals many states and countries have laid out, policymakers must have the best available information, and use it to guide policymaking.

Moreover, today’s economy is extraordinarily favorable for investment in renewable resources to make the leap policymakers know is necessary to avoid catastrophic climate effects. Low natural gas prices and the proliferation of energy efficiency technologies mean that utility bills will be kept low, providing a cushion for early investment in renewable resources. The cost of money is at an historic low, encouraging renewable developers to invest. And finally, federal tax incentives for solar and wind power are at peak levels.

Avoiding these four common myths about decarbonizing the power sector can help guide analysts and policymakers toward the solutions needed to reach an affordable, reliable, clean energy future.

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  • Jan Galkowski

    +Frank The renewables number is adversely low, a well-known problem with EIA data, which they recently admitted has issues.

    None of this discusses Sankey efficiencies, merely demand response and other improvements. Sankey efficiencies result from generation being (a) highly efficient, with near zero marginal cost, and (b) being located near the point of consumption. It also fails to address the need to satisfy energy requirements that the extended network to bring fossil fuels to generators. Zero Carbon technologies which generate near consumption have none of these.

    • John_ONeill

      As opposed to zero carbon technologies which have halfway decent capacity factors – solar from the deserts of Arizona or north Africa, or from southern Spain, wind from intemperate climes like Scotland, the US high plains, or the North Sea. You still need a grid to get power from there to somewhere people are willing to live. If Mark Jacobson had his way, there’d be massive networks of high voltage lines carrying gigawatts over continental distances – something fossil and nuclear dominated grids got on fine without.
      Or zero carbon technologies which outpower a thousand windmills for a year on one truckload of uranium.

      • JamesWimberley

        Big hydro plants, which are geographically determined, are very often in remote locations: Itaipu, Bratsk, James River. They needed, and got, the long-distance power lines.

        Why get excited about the argument between cheap + remote + big transmission, and dear + close + little transmission? It’s a matter of relative costs. The market will sort it out. If not, central planners: China is shifting its utility wind and solar emphasis from the cheap but remote interior to the dearer and populated east of the country. Don’t sacralize capacity factors.

      • Bob_Wallace

        Transmission lines don’t melt down requiring thousands of people to flee the area and leaving large areas uninhabitable.

        Transmission lines don’t leave behind millions of tons of radioactive waste.

        Wind, in the windy center of the US, is now under 4c/kWh. Unsubsidized. The cost of moving it to the East Coast (if that is actually necessary) is under 3c/kWh for a total of less than 7c/kWh.

        New nuclear in the US would cost 15c/kWh to 20c/kWh. Subsidized.

        Mark Jacobson and his group of researchers have released an accounting of how much wind, solar, geothermal, hydro, etc. each state would need to utilize to produce all their electricity in state.

        • Jens Stubbe

          Bob do you know why transmission is so absurdly expensive in USA ? 3c/kWh is down right crazy expensive.

          • Bob_Wallace

            Sorry, can’t explain it. That’s the cost for long distance transmission, HVDC. (And I don’t have a firm source for that.)

            What’s the cost of long distance in Europe? Is it a total cost, including payments to landowners?

          • Bob_Wallace

            “The cost of high voltage electricity transmission (as opposed to the costs of electric power distribution) is comparatively low, compared to all other costs arising in a consumer’s electricity bill. In the UK, transmission costs are about 0.2p/kWh ”


            That’s about 3c/kWh in US dollars.

            (I’m not finding a source for US prices that feels usable.)

          • Bobby

            In the quoted text, it says the transmission costs are 0.2 pence per kWh for UK. So that translates to about 0.3 US cents.

            Also, in the referenced discussion it is calculated that the costs for the European transnational HVDC Supergrid are 0.5 €ct/kWh. So even on that scale the costs are very low and it makes an obvious case for HVDC transmission.

          • Jens Stubbe

            These numbers looks more credible and are on a very stable and strong slope downwards simply because the technology develops with incredible speed because we need the technology.

            I think we can safely count on that this incredibly important piece of the puzzle will be sorted in an economical way.

          • Jens Stubbe

            If we stay in the UK centric costing model there is construction going on where the cost of the contracts are public.

            “The NSN link will have the capacity to transmit 1,400 MW of power passing through Norwegian and British waters. The 730 kilometer link will be the world’s longest subsea power interconnection, expected to enter commercial operation in 2021. ABB, a global power and automation technology leader, has won an order worth about $450 million to link the power grids of the United Kingdom and Norway.”

            If we assume 60% utilization (a fair guess for the capacity factor onshore plus a little power going in the other direction, then for a 25 year period the cost without maintenance, scrap value and interest will be $450.000.000 / (1400 x 365 x 24 x 25) * 0,6 = $0,002446184

            For Hornsrev 3 the cost associated is a high power station at sea with links to all turbines and a sea and landline about 200 km and the cost over 25 years again using the simple metrics is about half a cent.

            For Kriegers Flak there will be a subsea line connecting Denmark and Germany and possibly also Sweden.

            Anyway the cost associated with sea stations and HVDC are both dropping like stones in free fall. The sea stations because they follow the cost development of all high power electronics and HVDC because the capacity per weight is dropping fast. Recently Siemens has managed to develop a technology without sea stations because the weight and size is now small enough to fit in a turbine tower.

            What you need to get passed asap is right of way because a modern HVDC network is a matter of national security and key to modern industrialization of USA.

            Ps. there was another article on Cleantechnica about a private company that offered to connect the windy interior to the east for 2 cents per kWh, which by the looks of it seems to be an insanely good business case.

    • Frank

      I thought the problems with EIA was in their forecasts, not their measurement, except for not including behind the meter solar, which they now estimate. The point I was making is that the article suggested that the number of terrawatt hours of coal production replaced by renewables and gas are close, and what I see on EIA’s site is that gas displaced 2.75 times as much. I’m not trying to argue grid losses.

  • JamesWimberley

    Very US-centric. China uses little gas, having next to no domestic supply. European gas use is on a downward trend, and public opposition has prevented large-scale fracking.

    • Matt

      Myth 4 may only come up in the US. But it is a BIG one here.

    • super390

      China seems to be playing Iran and Russia against each other for its future natural gas needs. Pipelines are spreading between these countries. But that works in more than one direction; Russia could always use Chinese demand as a bluff to threaten a cutoff to Western Europe. And Iran sure would like to use Chinese demand to deter future US sanctions.

    • John_ONeill

      The article missed the other ‘ myth ‘ , that rather than reducing emissions, the US and Europe have just exported them to Asia, along with the associated manufacturing jobs. Cases in point, solar panels from Germany and the US to China, closure of Wales’ biggest steelmaker by the Indian company that bought it.

  • Jens Stubbe

    When debunking do use realistic figures please. Your statement “while natural gas still emits roughly half the carbon dioxide that coal does.” is completely nonsens. Not only is there less carbon in Methane per unit of energy but methane power plants whether they are combined cycle or peak power plants are also much more efficient than standard coal power plants and also releases far less vapor and gasses from cooling water. A typical peak power plant is up to plus 1.5 times more efficient than coal and a new combined cycle power plant is around 60% which is nearly double the efficiency of an old US coal power plant. I do not know the balance between peak power usage and baseload usage but let us assume 50%/50% then you get roughly three times less CO2 in the exhaust. Combining with the other GHG emissions form the power plants I think a fair guesstimate is that the GHG effect of an average US coal power is roughly four times that of an average Fracking gas based power plant.

    However both Fracking gas and coal excavation ooze a lot of methane directly into the atmosphere. Your just as bad as coal speculation is however sadly missing out on the huge methane amount oozing out of from mining, transporting and storing coal.

    We need to get of all forms of fossils asap and we can do it while also creating jobs and increasing growth.

    • Bob_Wallace

      “When debunking do use realistic figures please. Your statement “while natural gas still emits roughly half the carbon dioxide that coal does.” is completely nonsens. ”

      Below is a screen capture from your link.

      Depending on the type of coal used CO2 emissions range from 205.7 (bituminous) to 228.6 (anthracite) pounds of CO2 emitted per million British thermal units.

      Natural gas results in 117 pounds of CO2 emitted per million British thermal units.

      117 is 56.9% of 205.7

      117 is 51.2% of 228.6

      I’ll continue to use “roughly half” when I talk about CO2 emissions.

      I don’t think steam emissions turn into water vapor GHG, increased water vapor in the atmosphere is a function of air temperature.

      I will look for a reliable number for coal related methane leaks. If they are significant then that argues stronger for replacing coal with NG as we transition away from fossil fuels.

      (And you need to get over your snit. It’s become tiresome.)


      • Jens Stubbe

        I think you miss the point I made. The article considers natural gas to be half emission per produced kWh, which is an obvious misunderstanding. The source I provided is correct and the piece you chose to comment is correct and by the way clearly states British Thermal Units = the thermal energy you get when you burn the stuff, which is not the same as the kWh you get.

        That the authors has misunderstood or confused these values should be evident from the following quote from the article “while natural gas still emits roughly half the carbon dioxide that coal does. This means added renewable generation may have twice the impact of natural gas in reducing carbon dioxide emissions when it replaces coal.”

        If you have any say over the article I suggest you correct it because this actually shows how much more GHG renewables actually displace.

        • Bob_Wallace

          How about working up methane emission numbers from coal and NG “leakage”?

          Here’s what I was able to pull together after your earlier post (and now I’ve got to get on to non-CT business, won’t have time to do more until tonight).

          Raw data drop-

          A study by the National Renewable Energy Laboratory estimated that surface mining releases 1.91 grams of methane per kilogram of surface mined coal. The same study estimated that mining releases 4.23 grams of methane per kilogram of underground-mined coal.[7]

          (7) Pamela L. Spath et al, “Life Cycle Analysis of Coal-Fired Power Production,” National Renewable Energy Laboratory, June 1999

          Kilowatthour generated per unit of fuel used:

          1,927 kWh per ton, or 0.96 kWh per pound, of coal
          99 kWh per Mcf (1,000 cubic feet) of natural gas
          578 kWh per barrel, or 13.76 kWh per gallon, of petroleum

          Amount of fuel used to generate 1 kWh:

          Coal = 0.00052 short tons or 1.04 pounds
          Natural gas = 0.01011 Mcf (an Mcf equals 1,000 cubic feet)
          Petroleum = 0.00173 barrels (or 0.07 gallons)

          1.04 pounds of coal = 0.01011 Mcf natural gas

          The drilling and extraction of natural gas from wells and its transportation in pipelines results in the leakage of methane, a far more potent global warming gas than CO2. Preliminary studies and field measurements show that these so-called “fugitive” methane emissions range from 1 to 9 percent of total life cycle emissions [3].

          One recent study found that methane losses must be kept below 3.2 percent for natural gas power plants to have lower life cycle emissions than new coal plants over short time frames of 20 years or fewer [5].

          • Stan Hlegeris

            Pounds and BTUs? How about joining the current century with sensible units?

          • Bob_Wallace

            Take it up with the sources.

  • Frank

    When I look at these numbers gas production is up 518GWh, and other renewables are up 188 2006-2015 Not sure where the number for gas in the article came from.

    In this period of time, coal dropped from around 50% to around 33%. Thats a lot of percentage points to make up. Of course now, renewables prices are there, so lets get on with it. Production has been essentially flat for the last 10 very much supporting the efficiency argument.

    • Bob_Wallace

      NG has replaced a lot of coal over the last ten years (2005 coal 49.6%, NG 18.8% -> 2015 coal 33.2%, NG 32.7%).

      During that same ten years renewables have replaced about 5% of fossil fuel electricity market share.

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