國際能源署：要實現2050淨零碳排 仍須洪荒之力

The world’s best solar power schemes now offer the “cheapest…electricity in history” with the technology cheaper than coal and gas in most major countries.

That is according to the International Energy Agency’s World Energy Outlook 2020. The 464-page outlook, published today by the IEA, also outlines the “extraordinarily turbulent” impact of coronavirus and the “highly uncertain” future of global energy use over the next two decades.

Reflecting this uncertainty, this year’s version of the highly influential annual outlook offers four “pathways” to 2040, all of which see a major rise in renewables. The IEA’s main scenario has 43% more solar output by 2040 than it expected in 2018, partly due to detailed new analysis showing that solar power is 20-50% cheaper than thought.

Despite a more rapid rise for renewables and a “structural” decline for coal, the IEA says it is too soon to declare a peak in global oil use, unless there is stronger climate action. Similarly, it says demand for gas could rise 30% by 2040, unless the policy response to global warming steps up.

This means that, while global CO2 emissions have effectively peaked, they are “far from the immediate peak and decline” needed to stabilise the climate. The IEA says achieving net-zero emissions will require “unprecedented” efforts from every part of the global economy, not just the power sector.

The main WEO pathway is again the “stated policies scenario” (STEPS, formerly NPS). This shows the impact of government pledges to go beyond the current policy baseline. Crucially, however, the IEA makes its own assessment of whether governments are credibly following through on their targets.

The report explains:

“The STEPS is designed to take a detailed and dispassionate look at the policies that are either in place or announced in different parts of the energy sector. It takes into account long-term energy and climate targets only to the extent that they are backed up by specific policies and measures. In doing so, it holds up a mirror to the plans of today’s policy makers and illustrates their consequences, without second-guessing how these plans might change in future.”

The outlook then shows how plans would need to change to plot a more sustainable path. 

For the first time this year, the WEO has “detailed modelling” of a “net-zero emissions by 2050 case” (NZE2050). This shows what would need to happen for CO2 emissions to fall to 45% below 2010 levels by 2030 on the way to net-zero by 2050, with a 50% chance of meeting the 1.5C limit.

The final pathway in this year’s outlook is a “delayed recovery scenario” (DRS), which shows what might happen if the coronavirus pandemic lingers and the global economy takes longer to recover, with knock-on reductions in the growth of GDP and energy demand.

The chart below shows how the use of different energy sources changes under each of these pathways over the decade to 2030 (right-hand columns), relative to demand today (left).

Notably, renewables (light green) account for the majority of demand growth in all scenarios. In contrast, fossil fuels see progressively weaker growth turn to increasing declines, as the ambition of global climate policy increases, from left to right in the chart above.

One of the most significant shifts in this year’s WEO is tucked away in Annex B of the report, which shows the IEA’s estimates of the cost of different electricity generation technologies.

The table shows that solar electricity is some 20-50% cheaper today than the IEA had estimated in last year’s outlook, with the range depending on the region. There are similarly large reductions in the estimated costs of onshore and offshore wind.

This shift is the result of new analysis carried out by the WEO team, looking at the average “cost of capital” for developers looking to build new generating capacity. Previously the IEA assumed a range of 7-8% for all technologies, varying according to each country’s stage of development.

Now, the IEA has reviewed the evidence internationally and finds that for solar, the cost of capital is much lower, at 2.6-5.0% in Europe and the US, 4.4-5.5% in China and 8.8-10.0% in India, largely as a result of policies designed to reduce the risk of renewable investments.

In the best locations and with access to the most favourable policy support and finance, the IEA says the solar can now generate electricity “at or below” $20 per megawatt hour (MWh). It says:

“For projects with low-cost financing that tap high-quality resources, solar PV is now the cheapest source of electricity in history.”

The IEA says that new utility-scale solar projects now cost $30-60/MWh in Europe and the US and just $20-40/MWh in China and India, where “revenue support mechanisms” such as guaranteed prices are in place.

These costs “are entirely below the range of LCOE [levelised costs] for new coal-fired power plants” and “in the same range” as the operating cost of existing coal plants in China and India, the IEA says. This is shown in the chart below.

Onshore and offshore wind are also now assumed to have access to lower-cost finance. This accounts for the much lower cost estimates for these technologies in the latest WEO, because the cost of capital contributes up to half of the cost of new renewable developments.

When combined with changes in government policy over the past year, these lower costs mean that the IEA has again raised its outlook for renewables over the next 20 years.

This is shown in the chart below, where electricity generation from non-hydro renewables in 2040 is now seen reaching 12,872 terawatt hours (TWh) in the STEPS, up from 2,873TWh today. This is some 8% higher than expected last year and 22% above the level expected in 2018’s outlook.

Solar is the largest reason for this, with output in 2040 up 43% compared with the 2018 WEO. In contrast, the chart shows how electricity generation from coal is now “structurally” lower than previously expected, with output in 2040 some 14% lower than thought last year. The fuel never recovers from an estimated 8% drop in 2020 due to the coronavirus pandemic, the IEA says.

Notably, the level of gas generation in 2040 is also 6% lower in this year’s STEPS, again partly as a result of the pandemic and its long-lasting impact on economic and energy demand growth.

Overall, renewables – led by the “new king” solar – meet the vast majority of new electricity demand in the STEPS, accounting for 80% of the increase by 2030.

This means they overtake coal as the world’s largest source of power by 2025, outpacing the “accelerated case” set out by the agency just a year ago.

The lower costs and more rapid growth for solar seen in this year’s outlook means there will be record-breaking additions of new solar capacity in every year from 2020, the IEA says.

Successive editions of the WEO have revised down the outlook for the dirtiest fossil fuel, with this year seeing particularly dramatic changes, thanks in part to a “structural shift” away from coal after coronavirus.

The IEA now sees coal use rising marginally over the next few years, but then going into decline, as shown in the chart below (red line). Nevertheless, this trajectory falls far short of the cuts needed to be in line with the SDS, a pathway aligned to the “well-below 2C” Paris target (yellow).
Energy outlook

Taken together, the rapid rise of renewable energy and the structural decline for coal help keep a lid on global CO2 emissions, the outlook suggests. But steady demand for oil and rising gas use mean CO2 only flattens off, rather than declining rapidly as required to meet global climate goals.

These competing trends are shown in the chart, below, which tracks primary energy demand for each fuel under the IEA STEPS, with solid lines. Overall, renewables meet three-fifths of the increase in energy demand by 2040, while accounting for another two-fifths of the total. Smaller increases for oil and nuclear are enough to offset the decline in coal energy use.

The dashed lines in the chart above show the dramatically different paths that would need to be followed to be in line with the IEA SDS, which is roughly a well-below 2C scenario.

By 2040, although oil and gas would remain the first and second-largest sources of primary energy, there would have been declines in the use of all fossil fuels. Coal would have dropped by two-thirds, oil by a third and gas by 12%, relative to 2019 levels.

Meanwhile, other renewables – primarily wind and solar – would have surged to third place, rising nearly seven-fold over the next two decades (+662%). The SDS sees smaller, but still sizeable increases for hydro (+55%), nuclear (+55%) and bioenergy (+24%).

Together, low-carbon sources would make up 44% of the global energy mix in 2040, up from 19% in 2019. Coal would fall to 10%, its lowest since the industrial revolution, according to the IEA.

Despite these rapid changes, however, the world would not see net-zero CO2 emissions until 2070, some two decades after the 2050 deadline that would be needed to stay below 1.5C.

The WEO devotes a full chapter to the NZE2050, with a particular emphasis on the changes that would be needed over the next decade to 2030.

The power sector contributes the largest portion of the savings needed over the next decade (orange wedges in the chart, above). But there are also important contributions from energy end-use (yellow), such as transport and industry, as well as from individual behaviour change (blue), explored in more detail in the next section.

These three wedges would contribute roughly equal shares of the extra 6.4GtCO2 of savings needed to go from the SDS to the NZE2050 in 2030, the IEA says.

The NZE2050 case would see low-carbon sources of electricity meeting 75% of demand in 2030, up from 40% today. Solar capacity would have to rise at a rate of around 300 gigawatts (GW) per year by the mid-2020s and nearly 500GW by 2030, against current growth of around 100GW.

CO2 emissions from coal-fired power stations would decline by 75% between 2019 and 2030. This means the least efficient “subcritical” coal plants would be phased out entirely and the majority of “supercritical” plants would also close down. The WEO says the majority of this decline would come in southeast Asia, which accounts for two-thirds of current global coal capacity.

Although nuclear would contribute a small part of the increase in zero-carbon generation by 2030 in the NZE2050, the IEA notes that the “long lead time of large-scale nuclear facilities” limits the technology’s potential to scale more quickly this decade.

For industry, CO2 emissions would fall by around a quarter, with electrification and energy efficiency making up the largest shares of the effort. More than 2m homes would get an energy efficiency retrofit during every month this decade, in “advanced economies” alone.

In the transport sector, CO2 would fall by a fifth, not including behavioural shifts counted below. By 2030, more than half of new cars would be electric, up from around 2.5% in 2019.