Green Transport -1

Transport is a big problem area, consuming around 30% of world energy, nearly all via the use of fossil fuels. Whereas it’s relatively easy to see how green energy sources can meet power needs and even heating needs, mobility is a harder nut to crack, as we explore in this two part post.

In this first part we focus on road transport, which is responsible for around 15% of global emissions and around three quarters of total transport emissions, the first question to ask is – do we want to have private and commercial vehicles on roads as at present? Buses, trams, trains, bikes and walking may be better for many journeys- in environmental and also, compared to cars, in health terms: http://www.ukerc.ac.uk/network/network-news/guest-blog-buses-bicycles-and-building-for-health.html But assuming we still need private and commercial road vehicles for at least some purposes, the most direct and least disruptive way to reduce greenhouse gas emissions is to switch to lower carbon fuels- biofuels and synfuels.  However, even if the rate of use of biofuels is matched by the rate of replanting, there are still net carbon debts and eco-impacts- it takes energy to harvest and process the crops, CO2 remains in the atmosphere while the new plants grow, biodiversity may be undermined and there can be land-use conflicts with food growing. And with some low-yield biofuel crops the energy gains are marginal.   More productive advanced biofuel crops may improve on that, but the fuel cycle is still not carbon free, and the eco-impacts remain a big concern. Views differ, but it seems unlikely that we could grow enough biofuels to replace significant amounts of petrol and diesel use without having major eco-impacts.  

Synthetic fuels of various kinds may be better, but so far the costs are high. For example, it is possible to use electricity from wind or PV solar systems to electrolyse water to make 100% green hydrogen gas, for use either via combustion directly in car engines, or to run a fuel cell to make electricity for an electric motor drive. Unfortunately, these multiple ‘Power to Gas’ and ‘Gas to Power’ conversion steps each involve energy losses. If you have cheap electricity to start with that may not matter too much (and if its surplus wind or PV power, then it is in effect free), but even so, why not use it direct in a battery electric car? The conversion loses are then very low.

Certainly electric vehicles seem to be winning against hydrogen cars so far. Delivering electricity to car batteries is more straightforward than delivering liquid hydrogen to an on-board cryogenic tank. However, batteries are heavy and limit the car’s range. They are getting better, but in time some of the other options may win out in some sectors. For example, biofuels may have sourcing problems, but biogas, produced by anaerobic digestion of farm and food wastes, is a relatively cheap and quite widely available source and can be used in vehicles- although the volumes may not be very high. But in addition, liquified synthetic methane (CH4) can made from green hydrogen and CO2 captured from the air or from power station exhausts. That could be good for trucks and vans.  Some also look to synthetic methanol made from methane, or even ammonia as a new carbon molecule-free fuel.  But both are toxic…

For the moment most of the emphasis is on electric vehicles - and on stimulating up take.  They may cost less to run than conventional cars, but the battery pack adds to the cost and has to be replaced regularly. They also need charging!  EV owners can charge them at home, which may be fine for short commuting/shopping trips but for longer distance trips the UK is trying to get more public charging points established around the country. Ecotricity has already installed some at motorway services and there are some provided for example by local councils at other sites, in all around 11,000. The UK Department for Transport recently proposed plans to set common standards for all public charge points. But its also supporting hydrogen refuelling infrastructure.

Transport Secretary Chris Grayling said: ‘Our ambition is for nearly all new cars and vans to be zero emission by 2040.’ And subsequently Environment  Secretary Michael Grove announced a plan to halt all new petrol and diesel car sales by 2040. There is a way to go on that.  But the Government has a £4m programme to help businesses to switch their large trucks and vans to electric models through the Plug-In Van grant, as well as other grants and incentives for EV purchase. As a result, the number of new registered ultra-low emission vehicles (ULEVs) has risen by 250% in just two years, with more than £600m pledged so far over this Parliament to boost the market. The UK has the EUs second highest level of EV sales: http://www.edie.net/news/6/Government-unveils-charging-plans-to-put-EVs-in-driving-seat/

However, it’s still pretty marginal, as is the uptake of biofuels. The UK had agreed with an EU plan to increase the proportion of biofuel included in fuel mixes sold but that has proved hard and caps have been set by the EU in response to concerns about eco-impacts. At present liquid biofuel contributes around 3% of the fuel used in UK road transport. Sustainable sourcing has been an issue. Initially most biofuels were imported, but, REA says that ‘UK biodiesel is now largely made from waste feedstocks, in particular used cooking oil’, with no palm oil now being imported, and UK feedstocks for bioethanol have risen, so overall 26% of biofuels are now UK sourced, up from 8% in 2008:

http://www.r-e-a.net/news/new-department-for-transport-data-shows-no-palm-oil-used-in-the-uk

The situation in the USA is a bit different. Biofuels, bioethanol especially, prospered initially, driven by subsidy schemes aimed to help the beleaguered agricultural sector. Whether that helped much in net energy and emission terms is debated. So too is the more recent boom in electric vehicles (EVs). The US only gets around 15% of its electricity from renewables (as opposed to 25% and growing in the UK), so most of the EVs aren’t really very green. But the market for EVs is expanding. The Rocky Mountain Institute says ‘During the last decade, the number of plug-in vehicle models available for sale has grown to more than 20, just as battery costs have decreased by 70%, and the number of EV charging stations across the U.S. has climbed to more than 16,000. And this growth trajectory for EVs is likely to continue, especially with the Obama administration’s announcement in July 2016 of actions to accelerate deployment of EV charging infrastructure’.

However, the RMI notes that ‘load growth from new EVs can pose challenges to the distribution system and to electricity customers—affecting grid reliability and increasing electricity costs’. That’s also clear in the UK- it could lead to a 20% extra peak power demand.  But there are also some potential energy benefits. For example, as RMI notes, ‘technologies available today allow EVs to act as demand response resources and to assist with the integration of renewable energy onto the grid by managing when and where they charge’. Vehicle-to-grid (V2G) system need careful planning- no one will like it if they find their car batteries drained when they want to go somewhere or if the grid goes down if commuters all try to recharge their cars when they get home from work!  See the RMI’s report, Driving Integration: Regulatory responses to EV growth, for how these issue are being faced in the USA: http://www.rmi.org/ev_integration

So what’s the bottom line? Although public transport is by far the best environmentally, there are some green private road vehicle options and they are likely to expand. So we might hope to slow the rate of emissions in this sector.  EVs may come to the rescue, but it’s still pretty grim: road transport related emissions in the EU grew by 17% between 1990 and 2014: http://www.eea.europa.eu/highlights/eu-greenhouse-gas-emissions-at

It’s even worse for ships and planes. See the next post in this series.