Renewables have to double by 2030 to achieve climate targets

From PV Magazine:

At the start of what has been billed as a ‘decade of action’, the International Renewable Energy Agency (IRENA) has issued another call for a sustainable future. Stressing fossil fuel investment must be redirected, IRENA said annual renewable energy investment needs to more than double, from around $330 billion today to near $750 billion, to deploy renewable energy at the rate required.   
The 10 Years: Progress to Action study published for IRENA’s 10th annual assembly charts recent advances and outlines the measures still needed to scale up renewables. The Abu Dhabi-based agency says the world needs to double the share of renewables in the global energy mix over the next decade to achieve energy transition objectives. Renewables must account for 57% of generation, said IRENA, renewable electricity must account for 29% of final energy consumption and fossil-fuel use must decline 20%.  [A doubling over 10 years implies an annual growth rate of 7.1%.]

“We have entered the decade of renewable energy action, a period in which the energy system will transform at unparalleled speed,” said IRENA director-general Francesco La Camera. “To ensure this happens we must urgently address the need for stronger enabling policies and a significant increase in investment over the next 10 years. Renewables hold the key to sustainable development and should be central to energy and economic planning all over the world.”

Much of the investment needed could be met by redirecting fossil fuel funds. IRENA calculates almost $10 trillion of non-renewables energy investment is planned to 2030, risking stranded assets and increasing the likelihood of exceeding the world’s sub-1.5 degrees Celsius carbon budget this decade. By comparison, the world invested $3 trillion in renewables in the last 10 years.

A rise from $329 bln to $737 bln implies an 8.4% per annum growth rate. 
Actual capacity growth would be greater because of falling costs.

“We know it is possible, but we must all move faster,” La Camera said. Given falling technology costs, additional investments bring significant external savings, including minimizing the significant financial losses caused by climate change as a result of inaction. The potential savings could amount to $1.6-3.7 trillion per year by 2030, three to seven times higher than the investment cost of the energy transition, according to IRENA.

Renewables have already become the world’s main source of new power generation, as illustrated by the graph below. However, IRENA underlined renewables can also become the most competitive source of power by 2030. With 2.84 TW of solar generation capacity expected to have been installed in 2030, IRENA forecasts solar electricity prices of $34-40/MWh. Onshore wind costs are expected to be in the $30-40/MWh range with 2,015 GW of capacity installed worldwide at the end of the decade. The two energy sources would then account for a third of global power needs.

An extraordinary shift in just 9 years.  Note this appears to be gross not net new capacity.  With coal plants shutting down, renewables would make up a higher proportion of net new capacity.
The increase from 39% to 62% means that the compound growth rate was just 5.2% per annum.
This is likely to accelerate rather than decline (see comments below)
To eliminate coal power stations, the percentage of  new capacity coming from renewables has to exceed 100%

Already delivering electricity access to 150 million people [in emerging economies], renewables can become a vital tool in closing the energy access gap, said IRENA. Data produced by the agency shows 60% of new electricity access can be met by renewables in the next decade with standalone generation systems and mini-grids providing the means for almost half that new access.

IRENA also repeated its claim the global energy transition could be an employment bonanza. By 2030, there could be 30 million renewable energy jobs, including 11.7 million solar opportunities, up from 4.4 million last year.

My comments:

• The growth rates implied by IRENA's targets seem doable
•  Many forecasters (the IEA, for example) assume that the take-up of renewables will be limited because as the percentage of renewables rises we will reach 'saturation'—too much wind or solar will push down wholesale electricity prices when wind peaks or at midday when solar peaks.  But this assumes storage costs won't fall.  Falling storage costs will allow us to soak up excess power for release later when demand is higher or supply lower.  It's likely that growth rates could actually accelerate.  At a battery pack cost of $100/kWh, 24 hours of storage will cost just $15/MWh (assuming 20 year life)  Cheap storage allied to cheap electricity production from renewables is likely to lead to deployment accelerating rather than slowing.
• We must build no more coal power stations.  Not only would they add to carbon emissions but because of the plunge in the cost of renewables they will also risk being stranded assets.  With no new coal and 100%  of gross new investment consisting of renewables, the entire generation fleet would within decades be 100% renewable.