THE LIQUEFIED PETROLEUM GAS BIO-BUZZ LEAVING ASIDE THE APPARENT CONTRADICTIONS of a “liquefied gas” or having “bio” and “petroleum” in the same term, Liquefied Petroleum Gas (LPG) is a generic name for commercial blends of light gaseous hydrocarbons, predominantly propane (C₃H₈) and butane (C₄H₁₀). These change from a gaseous state at normal temperature and pressure to a liquid state when cooled or compressed at moderate pressure. This liquefaction property increases the density and, in its liquid state, the energy content of LPG on a per-tonne basis is higher compared to other fuels including most oil products. LPG is extracted as a by-product from crude oil refining or separated out from natural gas or oil production streams. LPG is normally refrigerated for shipment by sea and storage of large volumes at receiving terminals whereas smaller volumes are usually stored and distributed in pressurised vessels. It burns readily and cleanly in the presence of air giving off a hot flame with low NOx, SOx, aromatics and ultra-low soot emissions. LPG in itself is not a greenhouse gas (GHG) and is non-toxic. However being heavier than air it is hazardous and explosive. Residential sector largest user Being a function of oil and gas production LPG is supply driven. According to the 2013 “Statistical Review of Global LP Gas” jointly published by Argus and the World LP Gas Association, 2013 global LPG production reached just over 280 million tonnes and consumption was 265 million tonnes, both up just over 2 percent on 2012 figures, whereas the 15 million tonne gap between supply and demand remained the same. LPG accounts for around 2 percent of global primary energy supply. From a renewables perspective it is worth noting what LPG is used for. The residential sector is by far the biggest user, accounting for around 46 percent of all LPG consumed. In developed regions its use is highest in off-gas grid locations for heating and cooking whereas in other regions cooking fuel is the dominant use. Non-energy use in the petrochemicals sector accounts for about 25 percent of consumption whereas transport, industry, refinery and agriculture make up the balance. In Europe an estimated 6 million vehicles use LPG, “Autogas” as it is often called, as road transportation fuel and specific applications include machinery operating in confined spaces. BioDME and LPG Dimethyl ether (DME) is another non-toxic gas under normal temperature and pressure conditions but liquefies at about 6 bars and has properties similar to propane. According to the International DME Association, global DME produc- 32 Bioenergy International No 82, 6-2015 tion is a modest 5 million tonnes per annum and it is produced from a variety of fossil and biomass feedstock, notably methanol. DME has been used for decades as an aerosol propellant in the personal care industry. More recently it is attracting attention as a (bio)fuel for backup power generation, heating, cooking or transportation. In June the Swedish renewable DME producer LTU GREEN FUELS AB revealed that its BioDME is being tested for industrial heating usage blended with LPG (propane) in a project with FLOGAS SWEDEN AB. A subsidiary of UKheaded Flogas Europe, it is the country’s largest supplier and distributor of LPG having a 55 percent share of an “addressable” Swedish market of about 340 000 tonnes, the vast majority of which is propane used in industry for process heat. The BioDME from LTU Green Fuels is produced by gasification of black liquor, a by-product of the pulp industry, at its 1 000 tonne-per-annum pilot plant in Piteå, northern Sweden. In the project a first delivery of 20 percent BioDMEblended LPG has been shipped to an asphalt plant located by Stockholm Arlanda airport where it is currently being tested. Operated by Svevia, one of the largest road infrastructure construction and maintenance companies in Sweden, its Arlanda asphalt plant uses around 800 tonnes of LPG per annum supplied by Flogas Sweden. According to Jan Ström, Regional Manager, Flogas Sweden, the switch to using BioDME-blended LPG is easy and the market demand for renewable LPG is unquestionably there. – If we had sufficient volumes of BioDME tomorrow we could switch all our customers, Ström remarked during a visit to the Svevia asphalt plant in conjunction with the recent Advanced Biofuels conference in Stockholm Arlanda, Sweden. According to Ström up to 20 percent blend of BioDME in LPG is technically possible without any need to adjust equipment, whereas higher blends up to and including 100 percent BioDME require slight modifications. Based on its current market volume, a 20 percent blend for Flogas Sweden translates into a BioDME demand for around 37 400 tonnes of BioDME. It seems though that commercial-scale Bio- DME from black liquor, in Sweden at least, may take some time. According to Jonas Rudberg, Director for PORCUPINE, a consultancy company and one of the developers behind the LTU Green Fuels pilot plant, if and when commercial-scale BioDME from black liquor becomes a reality is dependent on stable long-term policy, a minimum of 13 years when allowing three year plant build. – It’s a policy-dependent financing issue. The technology for producing and using BioDME works. The black liquor feedstock is available and, as we can see, the market is ready and waiting. To build the first commercial 100 000 tonne-per-annum facility will require an investment of around SEK 3 billion (≈EUR 322 million), said Rudberg, during the said conference pointing out costs are likely to come down for subsequent plants. Biogas to BioDME or biopropane Others are building commercial BioDME but at much smaller scales and using different feedstock. Last year US-based OBERON FUELS, INC., received US Environmental Protection Agency (EPA) approval for its biogas-based DME for inclusion under the Renewable Fuel Standard (RFS) and earlier this year its DME was approved as a “legal” vehicle fuel by the State of California. Oberon Fuels has developed proprietary skid-mounted units that convert methane and carbon dioxide (CO₂) to DME from feedstock such as biogas and natural gas. Capacities are in the range SPOTLIGHT Ironic as it may seem, liquefied petroleum gas (LPG) can play an increasingly important role for developing biomass fuel markets as a whole. The specific characteristics of LPG and its advantages over other fuels – fossil and non-fossil alike – along with its current uses suggest LPG may be exceptionally well suited to act as a “bridging” fuel for renewables. Commercial pathways to produce Bio-LPG are emerging and the race is on to secure production and distribution. Figure 3:World final energy consumption of LPG by sector, 2013 121.7 67.5 29.9 25.8 17.9 4.2 140 120 100 80 60 40 20 0 Million tonnes * Including non-specified other final consumption. Source: Menecon Consulting analysis; WLPGA/Argus Media (2014). 46% 25% 11% 10% 7% 1% Residential Non-energy use (petrochemicals) Industry Transport Refinery Agriculture
Bioenergy no 6 October 2015
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