JULY 10, 2021 MARK HUTCHINS
From pv magazine 07/2021
pv magazine: It’s been more than 10 years since you first published work on a 100% renewables system – what has changed since then?
Mark Jacobson, director, atmosphere/energy program, Stanford University: The first article I published was back in 2009 in Scientific American. At the time utilities didn’t think much more than 20% renewables on the grid was possible, and when we proposed to go to 100%, people laughed at us.
Since then, everything has changed. There is a lot more discussion as to how we can get to 100% renewables, and whether the costs will go up. In the U.S. we now have around 24% renewable electricity. So, we are about 8% to 9% of the way there in terms of how far we need to go to get to 100% renewables for all energy, not just electricity, in the country.
There has been this huge growth of wind and solar, and now beginning with battery storage and electric vehicles as well. In the building sector people are starting to talk about more laws being passed to ensure new buildings are energy efficient and all electric. Heavy industries and air and ship transport are also starting to electrify. There is a lot of good news, but we still need very aggressive policies to be put in place to ensure that rapid transition – at least 80% by 2030, and 100% by 2050.
I think that the biggest obstacles right now are competing interests, all of these technologies being proposed that are actually much less helpful than renewables – so carbon capture, new nuclear power, bio energy, direct air capture, geoengineering. All of these things are basically opportunity costs and distractions from real solutions.
You’ve talked about a need for increased efficiency and energy demand reduction in a 100% wind water and sunlight scenario. How do these fit with the model?
Actually just by transitioning to 100% electricity, and providing that electricity with clean renewable energy, we would reduce global power demand by around 57%. Using heat pumps instead of gas heaters, for example, reduces your energy demand for heat by 75%. Same thing with electric vehicles – in a gasoline vehicle, 20% of the energy is used to move the car, and the rest is waste heat. Whereas in an electric vehicle 80% to 85% is used to move the car.
Additionally, 12% of energy worldwide is used for the mining, transport and refining of fossil fuels and uranium – and we eliminate all of that. Electrifying industry has a smaller benefit but about a 3% to 4% reduction is possible. And then there is another 6% to 7% in energy efficiency measures beyond ‘business as usual’. That all adds up to around a 57% reduction in energy requirements just by going to 100% clean renewable energy. And if you’re using 57% less energy, the cost per unit energy being the same, you’re paying 57% less per year. We calculate that worldwide the total annual cost that people pay will be about 60% lower. So about 57% less energy use and another 10% reduction in cost per unit energy.
So the cost per unit would fall by around 10%?
That’s a conservative estimate, because wind and solar right now are half the cost of natural gas. But OK, you need backup and you have more transmission and distribution – when you account for everything, it’s a minimum 10% lower cost of energy, but you are using 57% less energy. It’s a huge reduction in cost.
How does this backup look in your models? Is it all storage?
Demand response is also a very big component, and you have transmission interconnection over large areas. On one extreme you could have 100% storage and minimal interconnection, on the other you could just interconnect the world and have no storage, because you can always get renewable power from somewhere in the world. In reality you are going to have somewhere in between, and I think storage is winning because it is just getting harder to put up new transmission lines.