By Dave Elliott
A new report from Greenpeace says the world can be 100% renewable in energy by 2050, and 65% renewable in electricity in just 15 years. The 2015 Energy [R]evolution report, the latest iteration in its global and local scenario series, says global CO2 emissions could be stabilized by 2020 and would approach zero in 2050. Fossil fuels would be phased out, beginning with the most carbon-intensive sources. Greenpeace claims that, at every point during the transition, there would be more energy jobs than before. By 2030, renewable energy will account for 87% of the jobs in the energy sector, with 9.7 million people working in solar PV, equal to the number of people working in the coal industry today, and 7.8 million in wind, twice as many as are employed in oil and gas today.
It notes that the cost of renewable energy has fallen steeply in recent years, so that the resultant fuel savings from renewable investment are ‘cost neutral’. The extra investment costs for the global switch to 100% renewables by 2050 is put at about $1 trillion a year. But because renewables don’t need fuel, the average fuel cost savings are $1.07 trillion a year. So the investment over the period is met in full by fuel cost savings, with the cross-over happening between 2025 and 2030.
In terms of technology, along with energy efficiency, as you would expect, wind and solar are the major players, but with solar (at 32% of total global energy) leading wind (at 19%), because of the large solar heat input (38% of heating), along with a lot of PV and solar thermal CSP for electricity. Surprisingly, geothermal (heat and power) is the second largest single source, at 25%, ahead of biomass at 18%, that, along with hydro, being somewhat constrained by land-use and environmental considerations, with no biomass imports being allowed. And no nuclear or Carbon Capture and Storage (CCS) – or it seems, biomass with carbon capture (BECCS). The transport sector is the hardest to deal with, requiring changes in vehicle design, choice and use, and more buses and trains. Power to Gas and Power to Liquid conversion of renewable electricity is seen as a key for vehicle synfuel production. But overall Greenpeace see no major technological blocks to the transition. Though it will require strong political leadership to make it happen.
However, there are some interesting trade-offs to be thrashed out: for example, there’s an interesting discussion on scale, with, as an interim suggestion, 70% of projects being small and local, 30% based on larger and more centralised power plants. Greenpeace says ‘While a large proportion of global energy in 2050 will be produced by decentralised energy sources, large-scale renewable energy will still be needed for an energy revolution. Large offshore wind farms and concentrating solar power (CSP) plants in the Sunbelt regions of the world will therefore have an important but broader role to play. Offshore wind turbines produce electricity more hours of the day, thereby reducing the need for backup generators, and CSP with storage is dispatchable. Centralized renewable energy will also be needed to provide process heat for industry and desalination (in the case of CSP), to supply increased power demand for the heating and transport sector, and to produce synthetic fuels for the transport sector.’
The emphasis on local rather than central has implications for how transmission and grid balancing is dealt with. A fully decentral approach would make balancing harder: they suggest that this would mean having to have more capacity locally than would be the case if some power were imported. They say that ‘in principle, over-sizing local generation locally would reduce the need for large-scale renewable generation elsewhere as well as [for] upgrading the transmission network. In this case the local power system will evolve into a hybrid system that can operate without any outside support.’ However, they admit that ‘making local plants bigger (over-sized) is less economical than installing large-scale renewable energy plants at a regional scale and integrating them into the power system via extended transmission lines. The allocation [in their study] of 70% distributed renewable generation and 30% large-scale renewable generation is not based on a detailed technical or economic optimization; in each location, the optimum mix is specific to local conditions. Further detailed studies on regional levels will be needed to better quantify the split between distributed and large-scale renewable generation’.
Fair enough, there are some complex trade-offs, especially if we include storage in the mix. Greenpeace see this as playing a major role longer term. Even so, their emphasis on localisation at the expense of technical efficiency may need revisiting. That is also true of their linked ideas on transmission. They seem to want to keep this to a minimum, apparently worried about objections to new grid lines and that certainly fits in with their decentral approach – fewer links are envisaged. However they do look at the advantages of long distance transmission – HVDC supergrids and so on: they can be very efficient (maybe 2% losses over 1000km) and are easier (than AC) to put under ground. They also allow for the use of large projects sited in the best regimes for renewable energy collection. And, crucially, there’s the issue of trade, to enhance balancing of local variations in supply and demand. A still ongoing debate! For now though, imports from afar seem less popular, at least in Germany, with the near-demise of Desertec’s plans for importing solar power from North Africa. Though, as noted above, some CSP imports are included in the scenario.
The bottom line is grid balancing. Their scenario choices don’t make this easy. They say ‘the scenarios follow the strategy to limit the share of fluctuating power generation and to maintain a sufficient share of dispatchable, secured capacity. Therefore, power generation from biomass and CSP, but also a sufficient share of gas-fired back-up capacities and storage, are important factors for the security of supply in future energy systems’. However they have limited hydro and biomass, and also (most) imports, so that puts more stress on other types of balancing – mainly smart grid demand management and storage. They see smart grids as crucial and enabling the withdrawal from centralized large-scale units: ‘Renewable energy integrated into a smart grid changes the need for base load power. An energy switch based on renewables redefines the need for “base load” power generation. Instead, traditional base load power plants such as coal are replaced by a mix of flexible energy providers that can follow the load during the day and night (such as solar plus gas, geothermal, wind and demand management), without blackouts. The base load is therefore provided by a cascade of flexible power plants – instead of just baseload generation’.
The new system, with prosumers playing a major role, along with distributed power generation, will also require a new business model, less centralised management, operation and ownership. So it’s very much the decentralist approach, though leavened with some larger projects and with some interesting analysis of the funding options, which I will look at in my next post.
For the full report, setting a radical benchmark for the future, see: http://www.greenpeace.org/international/Global/international/publications/climate/2015/Energy-Revolution-2015-Full.pdf